The fact is, the country's blood supply runs on perilously thin margins. Just a few years ago, blood shortages occurred in late summer and around the Christmas holidays; these days, they often occur throughout the year because supply has not kept up with demand.
Shortages occur for numerous reasons, including generational differences and behaviors associated with giving blood and an increased need for blood transfusions. Blood banks work hard to make it as easy and convenient as possible to donate blood. Still, there are numerous restrictions on who can donate blood, with about 40 percent of the American population unable to donate.
Donating blood is relatively simple and entirely safe, however, taking just an hour and requiring little preparation. There is little to no risk of any adverse reaction when donating blood, and you can donate whole blood every 56 days; blood platelets every 48 hours, up to 24 times a year.
Women are critical to the country's blood supply, since their role as caregivers sends a message that donating blood is the right thing to do. However, they are also more likely than men to be temporarily restricted from donating because of low hematocrit, or red blood cell, levels if they are still menstruating.
The blood supply today is extremely safe, with the risk of catching a blood-borne disease via a transfusion miniscule. Research is underway to make the blood supply even safer via blood sterilization. Transfusions carry other risks, including the risk of receiving the wrong blood type and of contracting a rare lung condition that can be deadly.
During a transfusion, any one of several blood products may be transfused, including blood platelets, which help blood clot; red cells, which carry oxygen; and plasma, the watery fluid that transports cells and replaces blood volume.
There are four types of blood-O, A, B, and AB-and each type can be positive or negative, referred to as the Rh factor. In an emergency, anyone can receive type O blood, regardless of his or her own blood type.
Throughout your life, you will undergo numerous blood tests. The most common blood test, called a complete blood count, or CBC, measures the number of white and red blood cells, your hemoglobin and hematocrit values, and your platelet count. Another slew of blood tests, referred to as a comprehensive metabolic panel, provide important information about your kidneys, liver, blood sugar and blood proteins.
Current research in the field of blood transfusion is focusing on longer storage time for blood components and artificial blood products that, becaue they're artificial, don't require significant donations. However, some artificial blood products are developed with some donated blood products.
The Need for Blood
Every year, 4.5 million American lives are saved with blood transfusions, while an estimated 38,000 units-5,000 gallons-of donated blood are used each day in the U.S. Yet even though about 40,000 Americans donate blood each day, that's barely enough to keep the health care system running. The fact is, the country's blood supply runs on perilously thin margins. Just a few years ago, blood shortages occurred in late summer and around the Christmas holidays; these days, they often occur throughout the year because supply has not kept up with demand.
In a 1999 report from the National Blood Data Resources Center, an independent not-for-profit corporation, conceived and founded by the American Association of Blood Banks, nine percent of the nation's hospitals reported at least one day in which they had to cancel or postpone elective surgery because of a lack of red cell units. Half of those hospitals had to do this at least two days. Additionally, one-fourth of the hospitals could not meet their non-surgical blood requests at least one day, and for those experiencing such shortages, half were not able to meet it on at least five days. Since then, experts say, the situation has worsened.
It wouldn't take much to improve the situation. Just a five percent increase in the number of people who donate-about 40 more people in each state every day-would be enough to pull the nation's blood supply from the brink of disaster, experts say.
A major reason for the blood shortage is that even though 60 percent of the country's population is eligible to donate blood, only about five percent does. There are three main reasons for the shrinking numbers, say experts:
Changing demographics.
Since blood transfusions became commonplace in the 1950s, blood centers have depended on the World War II generation for donations. This generation is now aging and fewer, and Baby Boomers and the generations that follow simply don't donate as much. Experts aren't sure why, but suspect it may be related to differences in lifestyle, the level of altruism, and the fact that the blood community may not be effectively appealing to these generations.
Increasing need for blood.
As surgeries become more complex and cancer treatments more aggressive, and as people live longer, this country uses about five percent more blood every year.
Increasing blood donor rejection rate.
Beginning with the AIDS epidemic in the early 1980s, the blood supply has gotten much safer. But that's required turning away more and more potential donors. Today, increasingly sophisticated and sensitive tests, coupled with significantly more questions on application forms designed to weed out donors who may transmit blood-borne diseases, means there are fewer people who are able to donate blood even if they want to. For instance, people who have spent three or more months in the United Kingdom between 1980 and 1996 cannot donate blood for fear they could introduce the human version of mad-cow disease, variant Creutzfeldt-Jakob Disease (vCJD), into the blood supply.
There are other reasons for the shortage as well. For one, blood products are perishable. Red blood cells have a shelf life of 42 days, platelets just five days, so blood donations are needed every day, 365 days a year.
Then there are people's perceptions about blood donation. For instance, a study evaluating why people don't donate blood and other organs found that a persistent mistrust of doctors and hospitals as well as religious misconceptions played a major role. Minorities were particularly likely to avoid donation for these reasons. The study, which involved 20-minute phone interviews with 339 Baltimore, MD residents, found that African-American and Caucasian women were less willing to donate blood than Caucasian men (36 percent compared to 86 percent), while just 41 percent of African-American women surveyed said they would donate blood.
But the greatest barrier that prevents people from donating is a lack of convenience and a lack of knowledge of the importance of donating, experts say. And it is important. Every pint of donated blood saves three lives, and someone needs blood every three seconds.
Making Donation Convenient
A survey conducted by the American Red Cross found donors want to donate at or near a hospital, and generally don't want to travel more than 10 miles to donate. That's one reason why the American Red Cross, along with other blood banks, do all they can to bring opportunities to donate to the donors, through work-site and community blood drives.
To increase the amount of blood product collected during each donation (and thus reduce the number of donors needed), many blood centers now offer "double red blood cell donations". These are a different type of blood donation where,instead of collecting blood into individual collection bags as it comes from the donors' veins, the blood is collected into a machine. The machine keeps just the red blood cell portion of the blood and returns the other blood elements to the donor. In this way, two full doses of red cells, the most important part of the donation, can be collected at one time. Looked at another way: donors only have to donate blood once in order to give the equivalent of two blood donations. Unfortunately, many women do not qualify to donate double red cells because they have a lower overall blood volume than men.
But women are critical when it comes to this country's blood donors. As family caregivers, women hold a great deal of influence when it comes to blood donation. When a woman donates blood, experts say, she sends the message to others is that it is safe, painless and appropriate. She also sends a message that donating blood is a nurturing, selfless and kind act that is very much within the traditional role of women. Women also receive the majority of blood transfusions-about 53 percent.
However, when it comes to overall annual frequency of blood donation, men outpace women, donating an average of 1.68 times a year, compared to 1.53 times a year for women. An American Red Cross survey in 2002-2003 found that women 17- to 19-years-old are more likely to donate than men in the same age range. But at the other end of the spectrum-the 65-to74-year-old age range-they are significantly less likely to donate.
Who Can Donate
Although the U.S. Food and Drug Administration (FDA) sets most blood donation guidelines, some additional criteria are set by the blood donation centers. So the information below should be taken as a guide only. Check with your blood center about its specific rules. To find the closest blood center near you, just call either the American Red Cross or the America's Blood Centers hotlines, or visit their Web sites to set an appointment.
Donor eligibility rules are intended to protect the health and safety of the donor as well as the patient who will receive the transfusion. If you have any kind of medical condition, you should check with your health care professional about your ability to donate blood.
To be eligible to donate blood, you must be in good health and at least 17 years old (although some states permit younger people, with parental consent, to donate). Few have any upper age limit. Generally, donors must weight at least 110 pounds and all must pass a physical and health history examination given prior to donation. "Healthy" means you feel well and can perform normal activities. If you have a chronic condition such as diabetes or high blood pressure, "healthy" also means your condition is controlled with treatment.
Temporary DeferralIf you have experienced any of the following health situations in the bulleted list immediately below, you may find yourself "temporarily deferred." It means you can't give blood that day, but you can come back once you no longer meet the specific criteria.
This includes those who:
Have had a heart attack in the last six to 12 months.
Have had malaria in the last three years.
Have visited areas where malaria is found in the last year.
Have received blood, plasma or other types of blood components in the last year. You must wait 12 months after receiving a blood transfusion from another person in the United States before donating blood. And you may not donate if you received a transfusion since 1980 in the United Kingdom (England, Wales, Scotland, Northern Ireland, Channel Islands, Isle of Man), Gibraltar or Falkland Islands. This requirement is related to concerns about variant Creutzfeldt-Jakob disease (vCJD), or "mad cow" disease.
Have been tattooed in the last year (you must wait 12 months after a tattoo).
Have had cardiac surgery in the last year or have not completely recuperated from the surgery and are taking cardiovascular medicine.
Have been exposed to someone with hepatitis within the last year.
Are not feeling well the day of the blood donation.
Have taken antibiotics within the last 24 to 72 hours.
Are pregnant or have had an abortion in the last six weeks. Wait six weeks after giving birth before donating blood.
Have had oral surgery or treatment for an abscess or infection of the mouth. In this instance, you should wait three days before attempting to donate blood.
Have had immunizations for German measles (rubella), MMR (measles, mumps and rubella), or chicken pox. In those instances, wait four weeks before donating. If you've been immunized against red measles (rubeola), mumps, polio or yellow fever, wait two weeks. Wait seven days after immunization for Hepatitis B (unless you were given the immunization for exposure to hepatitis B. Then wait 12 months). There are also various waiting periods after receiving smallpox vaccine, depending on your reaction to the vaccine.
Have traveled in an area where malaria is found (wait 12 months). Wait three years after moving to the United States after living in a country where malaria is found.
Have been treated for syphilis or gonorrhea. Wait 12 months before donating.
Have been raped in the past 12 months.
Certain drugs also carry certain waiting periods. The Red Cross lists the following waiting times after you have taken your last dose:
Accutane (isotretinoin), Proscar (finasteride), and Propecia (finasteride): Wait four weeks.
Arava (leflunomide): Wait three months.
Avodart (dutasteride): Wait six months.
Aspirin: No waiting period for donating blood. However, you must wait 36 hours after taking aspirin or any medication containing aspirin before donating platelets by apheresis.
Coumadin, heparin or other prescription blood thinner: Wait five days after discontinuing.
Human pituitary-derived growth hormone: You are not eligible to donate blood.
Lupron (leuprolide acetate) used for condition other than cancer: Wait four months from last dose
Plavix (clopidogrel): Wait 36 hours before donating platelets by apheresis
Soriatane (acitretin): Wait three years before donating.
Tegison (etretinate): You are not eligible to donate blood.
Overall, you must wait at least eight weeks between whole blood (standard) donations, at least three days between platelet apheresis donations, and at least 16 weeks between double red cell (automated) donations.
Permanent Deferrals
If you meet any of the following criteria you will be permanently deferred, which means you cannot donate blood.
You have ever tested positive for hepatitis B or hepatitis C.
You have had hepatitis (inflammation of the liver) caused by a virus, or unexplained jaundice (yellow discoloration of the skin) since age 11.
You have received chemotherapy, hormonal therapy or immunotherapy for the treatment of cancer. If you only received radiation and surgery for the cancer and it has been five years since your last treatment with no recurrence, you may donate. Some low-risk cancers, including squamous or basal cell cancers of the skin, do not require a five-year waiting period. However, if you had leukemia or lymphoma, including Hodgkin's disease, you are not eligible to donate.
You are at high risk of contracting the HIV virus/AIDS or are already infected with the virus.
You have sickle cell disease.
You have spent any cumulative period of three or more months in the United Kingdom from 1980 through 1996.
You have received an injection of bovine (beef) insulin made from cattle from the United Kingdom since 1980. This requirement is related to concerns about variant Creutzfeldt-Jakob disease, or 'mad cow' disease.
You have a generalized autoimmune disease, including systemic lupus erythematosus and multiple sclerosis.
You have a clotting disorder, such as von Willebrand's disease or hemophilia. You should also not donate if you are taking any "blood thinner" medication such as Coumadin or heparin.
You have ever received a corneal (eye) transplant, a dura mater (brain covering) transplant or human pituitary growth hormone. This requirement is related to concerns about variant Creutzfeldt-Jacob disease. You are also not eligible to donate if you have a close family member who has had the disease, or if you are in a family that has been told they have a genetic risk for the disease.
Women and Blood Donation
One reason women donate blood less often than men may have to do with the fact that women who are still menstruating are more likely to have lower hematocrit, or red blood cell, levels than men. Having adequate iron stores is important for donation since iron is needed to make hemoglobin, the red pigment that carries oxygen inside red cells. Without adequate iron, you will not be able to make up for blood loss through menstruation or through donation. The U.S. Food and Drug Administration (FDA) requires that all donors have a blood hemoglobin level of at least 12.5 g/dL. So about eight out of every 100 people who turn up to donate blood-nearly all of them women-wind up being turned away, or "deferred," because of low hematocrit, or red blood cell, levels. Overall, about 30 percent of women who try to donate blood are deferred, or told to return at a later time.
That doesn't mean women can't eventually donate. They just need to get their iron levels up either through diet or supplements. Don't try to do this on your own, however. If you learn that your iron levels are low when you try to donate blood, see a health care professional. You may need prescription iron supplements to return your levels to normal.
One blood donation organization, America's Blood Centers, is testing a program in which women with low hemoglobin levels receive a supply of supplemental iron to take at home. When they finish the last pill, they're eligible to donate again. The hope is that this will not only improve a woman's hemoglobin level, but also increase the number of women who donate after deferral. Unfortunately, few people who are deferred ever return to donate.
If You Are Deferred
If you are temporarily deferred, or turned away, at a blood donation center, ask the staff at the blood center what you need to do to be able to donate. In some instances, you may just need to wait a few weeks. In others, you may need some medical attention. Don't take the deferral as a personal affront or insult. It definitely is not personal. And the blood centers really need your donation. So mark your calendar for the date when you can return to try again.
If you are permanently deferred, you cannot donate blood. But you can still help. Ask your blood center about volunteer opportunities, or offer to organize a community or workplace blood drive.
How to Donate
First, check the list of exceptions for donation to see if you are eligible to donate. If you have any questions, call your health care professional or your local blood donation center. To find the closest blood center near you, just call either the American Red Cross or the America's Blood Centers hotlines, or visit their Web sites to set an appointment.
On the day of your appointment, follow these recommendations:
Eat heartily and drink fluids (non-caffeinated, nonalcoholic) before you donate.
Don't exercise immediately before you donate blood.
Arrive on time. Most of the people staffing blood centers are volunteers. It's not fair to waste their time, and they try hard not to waste yours.
Bring a picture ID. You'll be asked to prove your identity.
Relax during the donation, which only takes about 10 to 15 minutes.
What to Expect
When you arrive, you'll register and answer a series of questions concerning your medical history. Then a medical staffer will conduct a health examination and measure your pulse, blood pressure, temperature and red cell level. You may feel a little pain when the needle goes in. Some people don't feel any pain. It might help to look away while the needle is inserted. You'll lie down for about 10 to15 minutes while a pint, or unit, of blood is collected.
Donating blood is strictly a volunteer activity-there is no payment. There are plasma centers in some cities, however, where you can receive compensation for donating plasma, the fluid that transports blood cells.
Apheresis Donation
In addition to the regular method of donating blood, in which the blood is permanently removed from your body, you may donate blood platelets through a process called apheresis. During this type of donation, blood passes through a special machine called a "blood cell separator" that uses centrifugal force (basically, spinning the blood around very fast) to separate the various blood components. The portion of the blood desired, such as the platelets, are then collected, while the rest of the blood products-plasma, hemoglobin and white blood cells-are returned to the donor.
Apheresis takes longer than traditional blood donation-about two hours-but it contains six to eight times more platelets than one whole blood donation. And because blood platelets are replenished quicker than red blood cells, you can donate every 48 hours, although no more than 24 times a year.
After Donating
After donating, you should receive a form with a number to call in case you learn after your donation that your blood may not be safe to give to another person. It is very important that you call that number if you discover that you have an infectious disease that can be spread through blood products.
Although most people feel fine after donating, a few have some nausea, a faint or dizzy feeling, or a black and blue mark, redness, or pain where the needle entered. This is perfectly normal.
After donating, you're asked to relax for a few minutes while you're served a light snack. While you're resting, ask the nurse for a large glass (about 16 ounces) of water. Two studies presented at the 2002 American Heart Association's High Blood Pressure Conference found drinking water before and after giving blood can prevent fainting.
After donating, you should avoid muscle exercises, rough movements and heavy activities such as weight lifting or picking up heavy objects for the first four to five hours after donation. Then mark your calendar: You can donate again in 56 days. If you donate every 56 days, you'll be able to donate six times a year. Over your lifetime, then (or until age 76) you could conceivably donate 48 gallons of blood!
Donation Safety
There is absolutely no way you can contract any virus or illness by donating blood. All materials used to collect blood are new. They have been sterilized by the manufacturer and never been used before and are thrown out immediately after use.
Safety of the Blood Supply
Thirty-six percent of Americans believe the U.S. blood supply is unsafe. The truth is, they are worrying for no reason. The U.S. blood supply today is so safe that the risk of contracting a disease such as HIV can only be estimated through mathematical techniques.
The FDA is responsible for ensuring the safety of the nation's blood supply. Overall, 14 different tests are performed on every unit of donated blood, including testing for seven different infectious agents: syphilis, hepatitis B and C, HTLV I and II (the virus that causes a form of leukemia), and HIV I and II. Today, blood centers use a testing protocol called NAT, or nucleic acid testing, to simultaneously test for HIV and Hepatitis C. NAT is capable of detecting more infectious donations than tests previously used because it detects viral genes rather than antibodies or antigens (proteins from the virus). This enables earlier detection, even before the donor knows he/she is infected, because the appearance of antibodies requires time for the donor to develop an immune response, and detection of antigens requires time for a higher level of virus to appear in the bloodstream.
Blood donors are also asked specific and very direct questions about risk factors that could indicate possible infection with a transmissible disease. This "up-front" screening eliminates approximately 90 percent of unsuitable donors. The FDA also requires blood centers to maintain lists of unsuitable donors to prevent the use of collections from them.
In recent years, the FDA has significantly increased its oversight of the blood industry. Today, the FDA inspects all blood facilities at least every two years, visiting "problem" facilities more often. Blood establishments are now held to quality standards comparable to those expected of pharmaceutical manufacturers.
The tight regulation of the blood supply means that blood centers can move quickly when new infectious disease agents are identified. For instance, when West Nile virus emerged in the U.S. in 1999, blood officials immediately began researching whether it could be transmitted via the blood supply. By late 2002, it was clear that the virus could be transmitted via blood products and in July 2003, officials implemented a post-donation test for the virus.
Blood Sterilization
Although the FDA notes on its Web site that a totally "risk-free" blood supply may never be attainable, researchers around the world still search for ways to reach that goal. One promising technique uses a procedure called "pathogen inactivation," or sterilization. The procedure involves adding a chemical to a bag of blood to "break up" the genetic material of any viruses or bacteria so they can't infect a recipient. However, two forms of sterilization for red cells have resulted in treated red cells that caused recipients' immune systems to make antibodies against the treated cells, so these trials are currently on hold until more can be learned about how to treat red cells without making them appear "foreign" to the recipient.
Types of Blood
Blood cells-red, which carry oxygen, white, which fight infection, and platelets, which help with clotting-are produced in your bone marrow. They are carried throughout your body in plasma, a pale yellow mixture of water, proteins (produced primarily in your liver) and salts. There are four main types of blood, and each type can be either Rh positive or negative:
Source: America's Blood Centers
Blood Type
Percentage of Population
O+ 38*
O- 7*
A+ 34
A- 6
B+ 9
B- 2
AB+ 3**
AB- 1**
*In an emergency, anyone can receive type O red blood cells. People with type O are known as "universal donors."**Type AB individuals can receive red blood cells of any ABO type. They are known as "universal recipients." They can also give plasma to all blood types.
The Rh Factor
The positive or negative nature of your blood type is called your Rh factor. You may have heard about Rh factor in connection with pregnancy. About 85 percent of Americans have Rh-positive blood. If you have Rh-negative blood and get pregnant by a man with Rh-positive blood, your children will most likely have Rh-positive blood. In every pregnancy, some blood cells from the fetus may pass through the placenta and enter your bloodstream. You may react to these "foreign" invaders as if you were allergic to them, building up antibodies capable of destroying them.
This is typically fine if this is your first pregnancy. But complications may occur with future pregnancies. By then, enough antibodies may have built up in your system so when they pass through the placenta to enter the fetus's blood they begin to destroy the baby's blood cells, producing anemia and possibly resulting in the death of the baby.
To prevent this, women who are Rh-negative who have had an Rh-positive baby should receive an injection of "Rh-immunoglobulin" within 72 hours after giving birth, having an abortion or miscarrying. This prevents Rh sensitization. In addition, they need to have the injection in the 28th week of their pregnancies to prevent the few red blood cells that cross the placenta into the mother's circulation during pregnancy from starting the immunization process.
Blood Tests and What They Mean
Blood comprises only nine percent of your total body weight. Yet just a few drops are all that's needed for the most common blood test, a complete blood count, or CBC. It includes five major measures that provide valuable clues to your overall health:
The reference ranges given below are slightly different for every laboratory. They should be regarded as approximations, and the results for a particular person's tests should be compared to the reference range for that lab.
White blood cell (WBC) count.
This measures the number and type of white blood cells, which fight infection. The "differential" is the measurement of the five main types of white blood cells: neutrophils (polys, or mature neutrophils, and bands, or young polys) basophils, eosinophils, lymphocytes and monocytes. A normal overall WBC range is 3.4-9.6 K/mm3, but you also want to know the results of the differential:
Normal range for neutrophils: 1,000 to 6,000/mm3
Normal range for lymphocytes: 15 to 51/mm3
Normal range for monocytes: 1 to12/mm3
Normal range for eosinophils: 0 to 8/mm3
Normal range for basophils: 0 to 8/mm3
Red blood cell (RBC) count.
Normal range is 3.58-4.99 mil/mm3. The mean cell volume (MCV) measures the approximate size of the red blood cell. A normal range is 77 to 99.
Hemoglobin (HGB) value.
Normal range is 11.1 to 15.0 g/dL. Low hematocrit and hemoglobin levels mean you could have anemia.
Hematocrit (HCT) value.
Normal range is 31.8 to 43.2 percent
Platelet count.
Normal range is 162 to 380 K/mm3. Without enough platelets, you could have a condition called "thrombocytopenia," which causes you to bruise easily.
Your health care professional may also order a comprehensive metabolic panel (CMP). These 14 tests, routinely ordered as part of a blood work-up for a medical exam or yearly physical, provide important information about the current status of your kidneys, liver and electrolyte and acid/base balance as well as your blood sugar and blood proteins. For best results, you should fast 10 to 12 hours prior to the test.
Not all tests described below have ranges listed for them because the American Association for Clinical Chemistry notes that reference ranges for many tests are specific to the laboratory that produces the results. Your test results should show you a "normal" range next to your result.
Glucose levels
Screens for and monitors diabetes, pre-diabetes and low blood sugar. Normal range is from 70 to 109 mg/dL. Levels from 110 to 125 mg/dL suggest pre-diabetes, and 126 mg/dL and above probable diabetes.
Calcium
Measures calcium levels in your blood.
Albumin
Screens for a liver disorder or kidney disease, or to evaluate nutritional status.
Total protein
Screens for certain liver and kidneys disorders, as well as other diseases, and helps determine your nutritional status.
Electrolytes:
Screens for sodium, potassium, carbon dioxide/bicarbonate and chloride levels. Among other things, provides an overview of your cardiovascular health.
BUN (blood urea nitrogen) and creatinine:
Evaluates your kidney function.
Liver function tests
Includes ALP (alkaline phosphatase), ALP or SGPT (alanine aminotransferase), aspartate amino transferase (AST or SGOT) and bilirubin.
Other blood tests you should periodically have include:
Thyroid test.
The American Thyroid Association recommends adults age 35 and older should be screened every five years for thyroid problems using the TSH test.
Cholesterol test
The National Cholesterol Education Program of the National Heart, Lung, and Blood Institute recommends everyone 20 and older have their blood cholesterol measured at least once every five years. Ideally, your total cholesterol should be below 200 mg/dL, your LDL (or "bad" cholesterol) less than 100 mg/dL and your HDL ("good" cholesterol) 60 mg/dL or more (the higher your HDL level the better).
Transfusing Blood
Types of Transfusions
When you give blood, you're actually giving several different products that can be transfused into several different people for various reasons. Blood is composed of plasma, platelets and red cells. All blood donations are processed and available for use approximately 24 and 48 hours after donation. After processing, red cells can be stored for 42 days, plasma can be frozen and stored for up to 12 months and platelets (from whole blood or by apheresis) expire after 5 days and are stored at room temperature.
How Are Blood Components Used?
Plasma is the watery fluid that transports cells and replaces blood volume. It is required to maintain blood pressure and assist in clotting, and also contains proteins that may help fight disease.
Platelets are proteins that help blood clot. They are transfused into patients undergoing transplants and those with leukemia and other cancers.
Red cells carry oxygen. They are transfused into patients with anemia, and those who have lost blood during surgery or trauma.
Blood Component Use
Units*
Automobile Accident
50 units of blood
Bone Marrow Transplant
20 units of blood
120 units of platelets
Burn
20 units of platelets
Heart Surgery
Six units of blood
Organ Transplant
40 units of blood
30 units of platelets
20 bags of cryoprecipitate
25 units of fresh frozen plasma
*Average usage.
Source: America's Blood Centers
Autologous Transfusions
Autologous blood donation, in which you donate your own blood for use during a surgical procedure, was quite popular in the early 1980s when the risk of HIV infection was very real. But today it's not worth doing if your community has an adequate blood supply.
Although autologous donations can spare you some of the very low infectious risks of using the available blood supply, from a cost/benefit standpoint it's a very expensive option to prevent a very few bad outcomes. Experts note that the use of autologous donation to prevent virus transmission can cost hundreds of thousands of dollars, if not millions, per infection avoided.
Half of all autologous donor blood doesn't even get used, and must be discarded. Plus, even if you donate your own blood, you may still have a reaction during the transfusion. Or, your donation could get mixed up with someone else's and used for the wrong patient. A survey by the American Association of Blood Banks suggested that one percent of all autologous units may be transfused to the wrong person.
Overall, experts agree, the safest alternative for medically needed transfusion remains your own blood, but, in most cases, this option adds very little from a safety perspective. Still, if you want an autologous blood transfusion for your own peace of mind, all blood centers offer the option.
Changing Standards for Blood Transfusion
One of the simplest ways to stretch the tight blood supply might be changing physician practices about when patients should get transfusions. A growing body of scientific literature suggests that one in every four or five transfusions might not be necessary. Traditionally, most doctors have transfused patients when their hemoglobin levels drop to 10 g/dL. But today, even in critical care units, many experts say the standard should be closer to 7 or 8 g/dL for many patients.
Reducing the number of blood transfusions this way could increase the nation's blood supply up to 25 percent, making blood more readily available to those in need. To move hospitals in this direction, some blood centers have full-time "transfusion safety officers" who work with hospitals on these and other transfusion-related items. But patients can also play a role, say experts, by asking their doctors: "Is this transfusion necessary?"
Blood Transfusion Safety
Transfusion errors pose a small, but significant risk to patients, occurring at the rate of two errors a day nationwide, on average.
And no one really knows how many result in death, since, until fairly recently, hospitals weren't required to report transfusion-related errors that did not result in death. Between 1990 and 1998, 161 deaths related to receiving the wrong blood type were reported to the FDA. Yet even if it doesn't result in death, any kind of reaction to the wrong blood can slow your recovery and increase your risk of complications.
The primary reason for most of blood-related errors is human mistakes. For instance, the sample from the patient may be mislabeled with another patient's name before it is sent to the lab, and then the wrong unit is sent to the patient for transfusion. Or, in the heat of crisis in the emergency room, someone forgets to double-check a patient's identity and match it with the label on the unit.
To avoid these errors, some hospitals have begun implementing bar code systems for blood transfusions, in which nurses use a scanning wand like those used in grocery stores to make sure the code on the blood matches the code on the patient's bracelet. Georgetown University Hospital in Washington, DC, for instance, hasn't had a single fatality related to transfusion error since implementing the bar code system in 1999. But overall, less than five percent of hospitals nationwide have implemented such technology.
In addition to your risk of getting the wrong blood, other risks include bacterial contamination of blood products, and a condition called "transfusion-related acute lung injury," a serious pulmonary syndrome that can lead to death if not recognized and treated appropriately. The syndrome is believed to be the third most common cause of blood transfusion-related death. There is also some concern that transfusion may affect the immune system and cause some mild immune suppression.
Future Research
For these and a multitude of other reasons-not the least of which is the chronically short blood supply-researchers have been scrambling to discover "artificial" blood products and means of maintaining blood products longer. For instance, clinical trials are underway on a biochemically modified hemoglobin solution called PolyHeme that contains hemoglobin, but no red blood cells. It looks red and is made from human blood, but does not need to be matched to a patient's blood type (since it contains no red cells) and it has a shelf life of one year. It is also safer than a human blood transfusion because it is virtually virus free. Other trials are ongoing with at least two other oxygen-carrying blood substitutes, including one made from cow's blood. But this kind of research is progressing slowly, with safety issues a key concern.
Other research efforts include work to extend the shelf life of donated blood. For instance, researchers in Sweden have developed dried blood that can be stored for years and used at a moment's notice. The blood "granules" have been used to successfully treat a group of patients in Stockholm for three years with no side effects.
Researchers are also investigating new methods for treating and chilling blood platelets to prolong their shelf life by a week or more. Currently, platelets must be stored at room temperature for no more than five days. While chilling the platelets lengthens the storage period, it causes certain receptors on platelet surfaces to clump together. This impels white blood cells called macrophages to recognize the platelets as foreign pathogens and destroy them. But adding a sugar molecule to these receptors, they do not cluster in the same way on cooling, and thus researchers think they have found a way to chill the platelets so they remain longer in the recipient blood stream. As of September 2003, they had only conducted studies in animals, so it is still unknown if the method will be safe and effective in humans.
Resources
American Red Cross
Shortages occur for numerous reasons, including generational differences and behaviors associated with giving blood and an increased need for blood transfusions. Blood banks work hard to make it as easy and convenient as possible to donate blood. Still, there are numerous restrictions on who can donate blood, with about 40 percent of the American population unable to donate.
Donating blood is relatively simple and entirely safe, however, taking just an hour and requiring little preparation. There is little to no risk of any adverse reaction when donating blood, and you can donate whole blood every 56 days; blood platelets every 48 hours, up to 24 times a year.
Women are critical to the country's blood supply, since their role as caregivers sends a message that donating blood is the right thing to do. However, they are also more likely than men to be temporarily restricted from donating because of low hematocrit, or red blood cell, levels if they are still menstruating.
The blood supply today is extremely safe, with the risk of catching a blood-borne disease via a transfusion miniscule. Research is underway to make the blood supply even safer via blood sterilization. Transfusions carry other risks, including the risk of receiving the wrong blood type and of contracting a rare lung condition that can be deadly.
During a transfusion, any one of several blood products may be transfused, including blood platelets, which help blood clot; red cells, which carry oxygen; and plasma, the watery fluid that transports cells and replaces blood volume.
There are four types of blood-O, A, B, and AB-and each type can be positive or negative, referred to as the Rh factor. In an emergency, anyone can receive type O blood, regardless of his or her own blood type.
Throughout your life, you will undergo numerous blood tests. The most common blood test, called a complete blood count, or CBC, measures the number of white and red blood cells, your hemoglobin and hematocrit values, and your platelet count. Another slew of blood tests, referred to as a comprehensive metabolic panel, provide important information about your kidneys, liver, blood sugar and blood proteins.
Current research in the field of blood transfusion is focusing on longer storage time for blood components and artificial blood products that, becaue they're artificial, don't require significant donations. However, some artificial blood products are developed with some donated blood products.
The Need for Blood
Every year, 4.5 million American lives are saved with blood transfusions, while an estimated 38,000 units-5,000 gallons-of donated blood are used each day in the U.S. Yet even though about 40,000 Americans donate blood each day, that's barely enough to keep the health care system running. The fact is, the country's blood supply runs on perilously thin margins. Just a few years ago, blood shortages occurred in late summer and around the Christmas holidays; these days, they often occur throughout the year because supply has not kept up with demand.
In a 1999 report from the National Blood Data Resources Center, an independent not-for-profit corporation, conceived and founded by the American Association of Blood Banks, nine percent of the nation's hospitals reported at least one day in which they had to cancel or postpone elective surgery because of a lack of red cell units. Half of those hospitals had to do this at least two days. Additionally, one-fourth of the hospitals could not meet their non-surgical blood requests at least one day, and for those experiencing such shortages, half were not able to meet it on at least five days. Since then, experts say, the situation has worsened.
It wouldn't take much to improve the situation. Just a five percent increase in the number of people who donate-about 40 more people in each state every day-would be enough to pull the nation's blood supply from the brink of disaster, experts say.
A major reason for the blood shortage is that even though 60 percent of the country's population is eligible to donate blood, only about five percent does. There are three main reasons for the shrinking numbers, say experts:
Changing demographics.
Since blood transfusions became commonplace in the 1950s, blood centers have depended on the World War II generation for donations. This generation is now aging and fewer, and Baby Boomers and the generations that follow simply don't donate as much. Experts aren't sure why, but suspect it may be related to differences in lifestyle, the level of altruism, and the fact that the blood community may not be effectively appealing to these generations.
Increasing need for blood.
As surgeries become more complex and cancer treatments more aggressive, and as people live longer, this country uses about five percent more blood every year.
Increasing blood donor rejection rate.
Beginning with the AIDS epidemic in the early 1980s, the blood supply has gotten much safer. But that's required turning away more and more potential donors. Today, increasingly sophisticated and sensitive tests, coupled with significantly more questions on application forms designed to weed out donors who may transmit blood-borne diseases, means there are fewer people who are able to donate blood even if they want to. For instance, people who have spent three or more months in the United Kingdom between 1980 and 1996 cannot donate blood for fear they could introduce the human version of mad-cow disease, variant Creutzfeldt-Jakob Disease (vCJD), into the blood supply.
There are other reasons for the shortage as well. For one, blood products are perishable. Red blood cells have a shelf life of 42 days, platelets just five days, so blood donations are needed every day, 365 days a year.
Then there are people's perceptions about blood donation. For instance, a study evaluating why people don't donate blood and other organs found that a persistent mistrust of doctors and hospitals as well as religious misconceptions played a major role. Minorities were particularly likely to avoid donation for these reasons. The study, which involved 20-minute phone interviews with 339 Baltimore, MD residents, found that African-American and Caucasian women were less willing to donate blood than Caucasian men (36 percent compared to 86 percent), while just 41 percent of African-American women surveyed said they would donate blood.
But the greatest barrier that prevents people from donating is a lack of convenience and a lack of knowledge of the importance of donating, experts say. And it is important. Every pint of donated blood saves three lives, and someone needs blood every three seconds.
Making Donation Convenient
A survey conducted by the American Red Cross found donors want to donate at or near a hospital, and generally don't want to travel more than 10 miles to donate. That's one reason why the American Red Cross, along with other blood banks, do all they can to bring opportunities to donate to the donors, through work-site and community blood drives.
To increase the amount of blood product collected during each donation (and thus reduce the number of donors needed), many blood centers now offer "double red blood cell donations". These are a different type of blood donation where,instead of collecting blood into individual collection bags as it comes from the donors' veins, the blood is collected into a machine. The machine keeps just the red blood cell portion of the blood and returns the other blood elements to the donor. In this way, two full doses of red cells, the most important part of the donation, can be collected at one time. Looked at another way: donors only have to donate blood once in order to give the equivalent of two blood donations. Unfortunately, many women do not qualify to donate double red cells because they have a lower overall blood volume than men.
But women are critical when it comes to this country's blood donors. As family caregivers, women hold a great deal of influence when it comes to blood donation. When a woman donates blood, experts say, she sends the message to others is that it is safe, painless and appropriate. She also sends a message that donating blood is a nurturing, selfless and kind act that is very much within the traditional role of women. Women also receive the majority of blood transfusions-about 53 percent.
However, when it comes to overall annual frequency of blood donation, men outpace women, donating an average of 1.68 times a year, compared to 1.53 times a year for women. An American Red Cross survey in 2002-2003 found that women 17- to 19-years-old are more likely to donate than men in the same age range. But at the other end of the spectrum-the 65-to74-year-old age range-they are significantly less likely to donate.
Who Can Donate
Although the U.S. Food and Drug Administration (FDA) sets most blood donation guidelines, some additional criteria are set by the blood donation centers. So the information below should be taken as a guide only. Check with your blood center about its specific rules. To find the closest blood center near you, just call either the American Red Cross or the America's Blood Centers hotlines, or visit their Web sites to set an appointment.
Donor eligibility rules are intended to protect the health and safety of the donor as well as the patient who will receive the transfusion. If you have any kind of medical condition, you should check with your health care professional about your ability to donate blood.
To be eligible to donate blood, you must be in good health and at least 17 years old (although some states permit younger people, with parental consent, to donate). Few have any upper age limit. Generally, donors must weight at least 110 pounds and all must pass a physical and health history examination given prior to donation. "Healthy" means you feel well and can perform normal activities. If you have a chronic condition such as diabetes or high blood pressure, "healthy" also means your condition is controlled with treatment.
Temporary DeferralIf you have experienced any of the following health situations in the bulleted list immediately below, you may find yourself "temporarily deferred." It means you can't give blood that day, but you can come back once you no longer meet the specific criteria.
This includes those who:
Have had a heart attack in the last six to 12 months.
Have had malaria in the last three years.
Have visited areas where malaria is found in the last year.
Have received blood, plasma or other types of blood components in the last year. You must wait 12 months after receiving a blood transfusion from another person in the United States before donating blood. And you may not donate if you received a transfusion since 1980 in the United Kingdom (England, Wales, Scotland, Northern Ireland, Channel Islands, Isle of Man), Gibraltar or Falkland Islands. This requirement is related to concerns about variant Creutzfeldt-Jakob disease (vCJD), or "mad cow" disease.
Have been tattooed in the last year (you must wait 12 months after a tattoo).
Have had cardiac surgery in the last year or have not completely recuperated from the surgery and are taking cardiovascular medicine.
Have been exposed to someone with hepatitis within the last year.
Are not feeling well the day of the blood donation.
Have taken antibiotics within the last 24 to 72 hours.
Are pregnant or have had an abortion in the last six weeks. Wait six weeks after giving birth before donating blood.
Have had oral surgery or treatment for an abscess or infection of the mouth. In this instance, you should wait three days before attempting to donate blood.
Have had immunizations for German measles (rubella), MMR (measles, mumps and rubella), or chicken pox. In those instances, wait four weeks before donating. If you've been immunized against red measles (rubeola), mumps, polio or yellow fever, wait two weeks. Wait seven days after immunization for Hepatitis B (unless you were given the immunization for exposure to hepatitis B. Then wait 12 months). There are also various waiting periods after receiving smallpox vaccine, depending on your reaction to the vaccine.
Have traveled in an area where malaria is found (wait 12 months). Wait three years after moving to the United States after living in a country where malaria is found.
Have been treated for syphilis or gonorrhea. Wait 12 months before donating.
Have been raped in the past 12 months.
Certain drugs also carry certain waiting periods. The Red Cross lists the following waiting times after you have taken your last dose:
Accutane (isotretinoin), Proscar (finasteride), and Propecia (finasteride): Wait four weeks.
Arava (leflunomide): Wait three months.
Avodart (dutasteride): Wait six months.
Aspirin: No waiting period for donating blood. However, you must wait 36 hours after taking aspirin or any medication containing aspirin before donating platelets by apheresis.
Coumadin, heparin or other prescription blood thinner: Wait five days after discontinuing.
Human pituitary-derived growth hormone: You are not eligible to donate blood.
Lupron (leuprolide acetate) used for condition other than cancer: Wait four months from last dose
Plavix (clopidogrel): Wait 36 hours before donating platelets by apheresis
Soriatane (acitretin): Wait three years before donating.
Tegison (etretinate): You are not eligible to donate blood.
Overall, you must wait at least eight weeks between whole blood (standard) donations, at least three days between platelet apheresis donations, and at least 16 weeks between double red cell (automated) donations.
Permanent Deferrals
If you meet any of the following criteria you will be permanently deferred, which means you cannot donate blood.
You have ever tested positive for hepatitis B or hepatitis C.
You have had hepatitis (inflammation of the liver) caused by a virus, or unexplained jaundice (yellow discoloration of the skin) since age 11.
You have received chemotherapy, hormonal therapy or immunotherapy for the treatment of cancer. If you only received radiation and surgery for the cancer and it has been five years since your last treatment with no recurrence, you may donate. Some low-risk cancers, including squamous or basal cell cancers of the skin, do not require a five-year waiting period. However, if you had leukemia or lymphoma, including Hodgkin's disease, you are not eligible to donate.
You are at high risk of contracting the HIV virus/AIDS or are already infected with the virus.
You have sickle cell disease.
You have spent any cumulative period of three or more months in the United Kingdom from 1980 through 1996.
You have received an injection of bovine (beef) insulin made from cattle from the United Kingdom since 1980. This requirement is related to concerns about variant Creutzfeldt-Jakob disease, or 'mad cow' disease.
You have a generalized autoimmune disease, including systemic lupus erythematosus and multiple sclerosis.
You have a clotting disorder, such as von Willebrand's disease or hemophilia. You should also not donate if you are taking any "blood thinner" medication such as Coumadin or heparin.
You have ever received a corneal (eye) transplant, a dura mater (brain covering) transplant or human pituitary growth hormone. This requirement is related to concerns about variant Creutzfeldt-Jacob disease. You are also not eligible to donate if you have a close family member who has had the disease, or if you are in a family that has been told they have a genetic risk for the disease.
Women and Blood Donation
One reason women donate blood less often than men may have to do with the fact that women who are still menstruating are more likely to have lower hematocrit, or red blood cell, levels than men. Having adequate iron stores is important for donation since iron is needed to make hemoglobin, the red pigment that carries oxygen inside red cells. Without adequate iron, you will not be able to make up for blood loss through menstruation or through donation. The U.S. Food and Drug Administration (FDA) requires that all donors have a blood hemoglobin level of at least 12.5 g/dL. So about eight out of every 100 people who turn up to donate blood-nearly all of them women-wind up being turned away, or "deferred," because of low hematocrit, or red blood cell, levels. Overall, about 30 percent of women who try to donate blood are deferred, or told to return at a later time.
That doesn't mean women can't eventually donate. They just need to get their iron levels up either through diet or supplements. Don't try to do this on your own, however. If you learn that your iron levels are low when you try to donate blood, see a health care professional. You may need prescription iron supplements to return your levels to normal.
One blood donation organization, America's Blood Centers, is testing a program in which women with low hemoglobin levels receive a supply of supplemental iron to take at home. When they finish the last pill, they're eligible to donate again. The hope is that this will not only improve a woman's hemoglobin level, but also increase the number of women who donate after deferral. Unfortunately, few people who are deferred ever return to donate.
If You Are Deferred
If you are temporarily deferred, or turned away, at a blood donation center, ask the staff at the blood center what you need to do to be able to donate. In some instances, you may just need to wait a few weeks. In others, you may need some medical attention. Don't take the deferral as a personal affront or insult. It definitely is not personal. And the blood centers really need your donation. So mark your calendar for the date when you can return to try again.
If you are permanently deferred, you cannot donate blood. But you can still help. Ask your blood center about volunteer opportunities, or offer to organize a community or workplace blood drive.
How to Donate
First, check the list of exceptions for donation to see if you are eligible to donate. If you have any questions, call your health care professional or your local blood donation center. To find the closest blood center near you, just call either the American Red Cross or the America's Blood Centers hotlines, or visit their Web sites to set an appointment.
On the day of your appointment, follow these recommendations:
Eat heartily and drink fluids (non-caffeinated, nonalcoholic) before you donate.
Don't exercise immediately before you donate blood.
Arrive on time. Most of the people staffing blood centers are volunteers. It's not fair to waste their time, and they try hard not to waste yours.
Bring a picture ID. You'll be asked to prove your identity.
Relax during the donation, which only takes about 10 to 15 minutes.
What to Expect
When you arrive, you'll register and answer a series of questions concerning your medical history. Then a medical staffer will conduct a health examination and measure your pulse, blood pressure, temperature and red cell level. You may feel a little pain when the needle goes in. Some people don't feel any pain. It might help to look away while the needle is inserted. You'll lie down for about 10 to15 minutes while a pint, or unit, of blood is collected.
Donating blood is strictly a volunteer activity-there is no payment. There are plasma centers in some cities, however, where you can receive compensation for donating plasma, the fluid that transports blood cells.
Apheresis Donation
In addition to the regular method of donating blood, in which the blood is permanently removed from your body, you may donate blood platelets through a process called apheresis. During this type of donation, blood passes through a special machine called a "blood cell separator" that uses centrifugal force (basically, spinning the blood around very fast) to separate the various blood components. The portion of the blood desired, such as the platelets, are then collected, while the rest of the blood products-plasma, hemoglobin and white blood cells-are returned to the donor.
Apheresis takes longer than traditional blood donation-about two hours-but it contains six to eight times more platelets than one whole blood donation. And because blood platelets are replenished quicker than red blood cells, you can donate every 48 hours, although no more than 24 times a year.
After Donating
After donating, you should receive a form with a number to call in case you learn after your donation that your blood may not be safe to give to another person. It is very important that you call that number if you discover that you have an infectious disease that can be spread through blood products.
Although most people feel fine after donating, a few have some nausea, a faint or dizzy feeling, or a black and blue mark, redness, or pain where the needle entered. This is perfectly normal.
After donating, you're asked to relax for a few minutes while you're served a light snack. While you're resting, ask the nurse for a large glass (about 16 ounces) of water. Two studies presented at the 2002 American Heart Association's High Blood Pressure Conference found drinking water before and after giving blood can prevent fainting.
After donating, you should avoid muscle exercises, rough movements and heavy activities such as weight lifting or picking up heavy objects for the first four to five hours after donation. Then mark your calendar: You can donate again in 56 days. If you donate every 56 days, you'll be able to donate six times a year. Over your lifetime, then (or until age 76) you could conceivably donate 48 gallons of blood!
Donation Safety
There is absolutely no way you can contract any virus or illness by donating blood. All materials used to collect blood are new. They have been sterilized by the manufacturer and never been used before and are thrown out immediately after use.
Safety of the Blood Supply
Thirty-six percent of Americans believe the U.S. blood supply is unsafe. The truth is, they are worrying for no reason. The U.S. blood supply today is so safe that the risk of contracting a disease such as HIV can only be estimated through mathematical techniques.
The FDA is responsible for ensuring the safety of the nation's blood supply. Overall, 14 different tests are performed on every unit of donated blood, including testing for seven different infectious agents: syphilis, hepatitis B and C, HTLV I and II (the virus that causes a form of leukemia), and HIV I and II. Today, blood centers use a testing protocol called NAT, or nucleic acid testing, to simultaneously test for HIV and Hepatitis C. NAT is capable of detecting more infectious donations than tests previously used because it detects viral genes rather than antibodies or antigens (proteins from the virus). This enables earlier detection, even before the donor knows he/she is infected, because the appearance of antibodies requires time for the donor to develop an immune response, and detection of antigens requires time for a higher level of virus to appear in the bloodstream.
Blood donors are also asked specific and very direct questions about risk factors that could indicate possible infection with a transmissible disease. This "up-front" screening eliminates approximately 90 percent of unsuitable donors. The FDA also requires blood centers to maintain lists of unsuitable donors to prevent the use of collections from them.
In recent years, the FDA has significantly increased its oversight of the blood industry. Today, the FDA inspects all blood facilities at least every two years, visiting "problem" facilities more often. Blood establishments are now held to quality standards comparable to those expected of pharmaceutical manufacturers.
The tight regulation of the blood supply means that blood centers can move quickly when new infectious disease agents are identified. For instance, when West Nile virus emerged in the U.S. in 1999, blood officials immediately began researching whether it could be transmitted via the blood supply. By late 2002, it was clear that the virus could be transmitted via blood products and in July 2003, officials implemented a post-donation test for the virus.
Blood Sterilization
Although the FDA notes on its Web site that a totally "risk-free" blood supply may never be attainable, researchers around the world still search for ways to reach that goal. One promising technique uses a procedure called "pathogen inactivation," or sterilization. The procedure involves adding a chemical to a bag of blood to "break up" the genetic material of any viruses or bacteria so they can't infect a recipient. However, two forms of sterilization for red cells have resulted in treated red cells that caused recipients' immune systems to make antibodies against the treated cells, so these trials are currently on hold until more can be learned about how to treat red cells without making them appear "foreign" to the recipient.
Types of Blood
Blood cells-red, which carry oxygen, white, which fight infection, and platelets, which help with clotting-are produced in your bone marrow. They are carried throughout your body in plasma, a pale yellow mixture of water, proteins (produced primarily in your liver) and salts. There are four main types of blood, and each type can be either Rh positive or negative:
Source: America's Blood Centers
Blood Type
Percentage of Population
O+ 38*
O- 7*
A+ 34
A- 6
B+ 9
B- 2
AB+ 3**
AB- 1**
*In an emergency, anyone can receive type O red blood cells. People with type O are known as "universal donors."**Type AB individuals can receive red blood cells of any ABO type. They are known as "universal recipients." They can also give plasma to all blood types.
The Rh Factor
The positive or negative nature of your blood type is called your Rh factor. You may have heard about Rh factor in connection with pregnancy. About 85 percent of Americans have Rh-positive blood. If you have Rh-negative blood and get pregnant by a man with Rh-positive blood, your children will most likely have Rh-positive blood. In every pregnancy, some blood cells from the fetus may pass through the placenta and enter your bloodstream. You may react to these "foreign" invaders as if you were allergic to them, building up antibodies capable of destroying them.
This is typically fine if this is your first pregnancy. But complications may occur with future pregnancies. By then, enough antibodies may have built up in your system so when they pass through the placenta to enter the fetus's blood they begin to destroy the baby's blood cells, producing anemia and possibly resulting in the death of the baby.
To prevent this, women who are Rh-negative who have had an Rh-positive baby should receive an injection of "Rh-immunoglobulin" within 72 hours after giving birth, having an abortion or miscarrying. This prevents Rh sensitization. In addition, they need to have the injection in the 28th week of their pregnancies to prevent the few red blood cells that cross the placenta into the mother's circulation during pregnancy from starting the immunization process.
Blood Tests and What They Mean
Blood comprises only nine percent of your total body weight. Yet just a few drops are all that's needed for the most common blood test, a complete blood count, or CBC. It includes five major measures that provide valuable clues to your overall health:
The reference ranges given below are slightly different for every laboratory. They should be regarded as approximations, and the results for a particular person's tests should be compared to the reference range for that lab.
White blood cell (WBC) count.
This measures the number and type of white blood cells, which fight infection. The "differential" is the measurement of the five main types of white blood cells: neutrophils (polys, or mature neutrophils, and bands, or young polys) basophils, eosinophils, lymphocytes and monocytes. A normal overall WBC range is 3.4-9.6 K/mm3, but you also want to know the results of the differential:
Normal range for neutrophils: 1,000 to 6,000/mm3
Normal range for lymphocytes: 15 to 51/mm3
Normal range for monocytes: 1 to12/mm3
Normal range for eosinophils: 0 to 8/mm3
Normal range for basophils: 0 to 8/mm3
Red blood cell (RBC) count.
Normal range is 3.58-4.99 mil/mm3. The mean cell volume (MCV) measures the approximate size of the red blood cell. A normal range is 77 to 99.
Hemoglobin (HGB) value.
Normal range is 11.1 to 15.0 g/dL. Low hematocrit and hemoglobin levels mean you could have anemia.
Hematocrit (HCT) value.
Normal range is 31.8 to 43.2 percent
Platelet count.
Normal range is 162 to 380 K/mm3. Without enough platelets, you could have a condition called "thrombocytopenia," which causes you to bruise easily.
Your health care professional may also order a comprehensive metabolic panel (CMP). These 14 tests, routinely ordered as part of a blood work-up for a medical exam or yearly physical, provide important information about the current status of your kidneys, liver and electrolyte and acid/base balance as well as your blood sugar and blood proteins. For best results, you should fast 10 to 12 hours prior to the test.
Not all tests described below have ranges listed for them because the American Association for Clinical Chemistry notes that reference ranges for many tests are specific to the laboratory that produces the results. Your test results should show you a "normal" range next to your result.
Glucose levels
Screens for and monitors diabetes, pre-diabetes and low blood sugar. Normal range is from 70 to 109 mg/dL. Levels from 110 to 125 mg/dL suggest pre-diabetes, and 126 mg/dL and above probable diabetes.
Calcium
Measures calcium levels in your blood.
Albumin
Screens for a liver disorder or kidney disease, or to evaluate nutritional status.
Total protein
Screens for certain liver and kidneys disorders, as well as other diseases, and helps determine your nutritional status.
Electrolytes:
Screens for sodium, potassium, carbon dioxide/bicarbonate and chloride levels. Among other things, provides an overview of your cardiovascular health.
BUN (blood urea nitrogen) and creatinine:
Evaluates your kidney function.
Liver function tests
Includes ALP (alkaline phosphatase), ALP or SGPT (alanine aminotransferase), aspartate amino transferase (AST or SGOT) and bilirubin.
Other blood tests you should periodically have include:
Thyroid test.
The American Thyroid Association recommends adults age 35 and older should be screened every five years for thyroid problems using the TSH test.
Cholesterol test
The National Cholesterol Education Program of the National Heart, Lung, and Blood Institute recommends everyone 20 and older have their blood cholesterol measured at least once every five years. Ideally, your total cholesterol should be below 200 mg/dL, your LDL (or "bad" cholesterol) less than 100 mg/dL and your HDL ("good" cholesterol) 60 mg/dL or more (the higher your HDL level the better).
Transfusing Blood
Types of Transfusions
When you give blood, you're actually giving several different products that can be transfused into several different people for various reasons. Blood is composed of plasma, platelets and red cells. All blood donations are processed and available for use approximately 24 and 48 hours after donation. After processing, red cells can be stored for 42 days, plasma can be frozen and stored for up to 12 months and platelets (from whole blood or by apheresis) expire after 5 days and are stored at room temperature.
How Are Blood Components Used?
Plasma is the watery fluid that transports cells and replaces blood volume. It is required to maintain blood pressure and assist in clotting, and also contains proteins that may help fight disease.
Platelets are proteins that help blood clot. They are transfused into patients undergoing transplants and those with leukemia and other cancers.
Red cells carry oxygen. They are transfused into patients with anemia, and those who have lost blood during surgery or trauma.
Blood Component Use
Units*
Automobile Accident
50 units of blood
Bone Marrow Transplant
20 units of blood
120 units of platelets
Burn
20 units of platelets
Heart Surgery
Six units of blood
Organ Transplant
40 units of blood
30 units of platelets
20 bags of cryoprecipitate
25 units of fresh frozen plasma
*Average usage.
Source: America's Blood Centers
Autologous Transfusions
Autologous blood donation, in which you donate your own blood for use during a surgical procedure, was quite popular in the early 1980s when the risk of HIV infection was very real. But today it's not worth doing if your community has an adequate blood supply.
Although autologous donations can spare you some of the very low infectious risks of using the available blood supply, from a cost/benefit standpoint it's a very expensive option to prevent a very few bad outcomes. Experts note that the use of autologous donation to prevent virus transmission can cost hundreds of thousands of dollars, if not millions, per infection avoided.
Half of all autologous donor blood doesn't even get used, and must be discarded. Plus, even if you donate your own blood, you may still have a reaction during the transfusion. Or, your donation could get mixed up with someone else's and used for the wrong patient. A survey by the American Association of Blood Banks suggested that one percent of all autologous units may be transfused to the wrong person.
Overall, experts agree, the safest alternative for medically needed transfusion remains your own blood, but, in most cases, this option adds very little from a safety perspective. Still, if you want an autologous blood transfusion for your own peace of mind, all blood centers offer the option.
Changing Standards for Blood Transfusion
One of the simplest ways to stretch the tight blood supply might be changing physician practices about when patients should get transfusions. A growing body of scientific literature suggests that one in every four or five transfusions might not be necessary. Traditionally, most doctors have transfused patients when their hemoglobin levels drop to 10 g/dL. But today, even in critical care units, many experts say the standard should be closer to 7 or 8 g/dL for many patients.
Reducing the number of blood transfusions this way could increase the nation's blood supply up to 25 percent, making blood more readily available to those in need. To move hospitals in this direction, some blood centers have full-time "transfusion safety officers" who work with hospitals on these and other transfusion-related items. But patients can also play a role, say experts, by asking their doctors: "Is this transfusion necessary?"
Blood Transfusion Safety
Transfusion errors pose a small, but significant risk to patients, occurring at the rate of two errors a day nationwide, on average.
And no one really knows how many result in death, since, until fairly recently, hospitals weren't required to report transfusion-related errors that did not result in death. Between 1990 and 1998, 161 deaths related to receiving the wrong blood type were reported to the FDA. Yet even if it doesn't result in death, any kind of reaction to the wrong blood can slow your recovery and increase your risk of complications.
The primary reason for most of blood-related errors is human mistakes. For instance, the sample from the patient may be mislabeled with another patient's name before it is sent to the lab, and then the wrong unit is sent to the patient for transfusion. Or, in the heat of crisis in the emergency room, someone forgets to double-check a patient's identity and match it with the label on the unit.
To avoid these errors, some hospitals have begun implementing bar code systems for blood transfusions, in which nurses use a scanning wand like those used in grocery stores to make sure the code on the blood matches the code on the patient's bracelet. Georgetown University Hospital in Washington, DC, for instance, hasn't had a single fatality related to transfusion error since implementing the bar code system in 1999. But overall, less than five percent of hospitals nationwide have implemented such technology.
In addition to your risk of getting the wrong blood, other risks include bacterial contamination of blood products, and a condition called "transfusion-related acute lung injury," a serious pulmonary syndrome that can lead to death if not recognized and treated appropriately. The syndrome is believed to be the third most common cause of blood transfusion-related death. There is also some concern that transfusion may affect the immune system and cause some mild immune suppression.
Future Research
For these and a multitude of other reasons-not the least of which is the chronically short blood supply-researchers have been scrambling to discover "artificial" blood products and means of maintaining blood products longer. For instance, clinical trials are underway on a biochemically modified hemoglobin solution called PolyHeme that contains hemoglobin, but no red blood cells. It looks red and is made from human blood, but does not need to be matched to a patient's blood type (since it contains no red cells) and it has a shelf life of one year. It is also safer than a human blood transfusion because it is virtually virus free. Other trials are ongoing with at least two other oxygen-carrying blood substitutes, including one made from cow's blood. But this kind of research is progressing slowly, with safety issues a key concern.
Other research efforts include work to extend the shelf life of donated blood. For instance, researchers in Sweden have developed dried blood that can be stored for years and used at a moment's notice. The blood "granules" have been used to successfully treat a group of patients in Stockholm for three years with no side effects.
Researchers are also investigating new methods for treating and chilling blood platelets to prolong their shelf life by a week or more. Currently, platelets must be stored at room temperature for no more than five days. While chilling the platelets lengthens the storage period, it causes certain receptors on platelet surfaces to clump together. This impels white blood cells called macrophages to recognize the platelets as foreign pathogens and destroy them. But adding a sugar molecule to these receptors, they do not cluster in the same way on cooling, and thus researchers think they have found a way to chill the platelets so they remain longer in the recipient blood stream. As of September 2003, they had only conducted studies in animals, so it is still unknown if the method will be safe and effective in humans.
Resources
American Red Cross
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