Basics About Blood
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Human blood is made of four main components, plasma, platelets, red blood cells and white blood cells. The 55% of blood is just plasma, which is mostly water, but also contains proteins, immunoglobulins, vitamins and other substances. Blood makes up 7% of your body weight.
All animals have varying numbers of blood types. Cows have a whopping 800 types of blood. Humans have four blood types, A, B, AB, and O and these can be further identified by their RH positive or negative status. Over 70% of Americans are either type O+ or A+.
While you probably already know that type O is the universal donor for red blood cells, most people are unaware that plasma transfusions are the exact opposite and people with type AB blood are universal plasma donors.
Types of Donations
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When you donate blood, you generally give around one pint of whole blood per donation, which makes up anywhere from a tenth to a twelfth of your body’s total blood. This is why some people (myself included) feel weak after donation, but most people are fine after blood withdrawal. Most people feel fine within a few hours, but it still takes your body up to three days to replace the donated plasma and up to 59 days for you to recover your red blood cells. That’s why you can only donate every few months.
While most people donate whole blood, there is another option called Apheresis. When you donate just plasma and platelets, this method is used for withdrawal. Basically, your blood is removed from your arm and then passed through a machine that separates out the contents of your blood. The parts of your blood that are being donated are kept separate and the rest of your blood is returned into your body. In most cases, the red blood cells are returned since these take the longest to regenerate. That’s why platelet and plasma donors can donate every three days. While it takes up to ten units of whole blood to make up one whole dose of platelets for a patient, this method can collect at least one whole dose of platelets with each donation.
While blood can be directly transfused from the donor into the patient, this method was largely phased out after WWII and blood donations are usually stored these days. Red blood cells can be stored for up to 42 days and plasma can be stored for a full year. Unfortunately, platelets can only be kept for about a week.
Why Are Blood Banks Always Working?
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Blood banks are always looking to get more supply, and there are a number of reasons for this. First, a lot of people need blood. In fact, it is estimated that someone in the U.S. needs a transfusion every two seconds and that one in four Americans will need a transfusion at some point in their life. Secondly, because the majority of blood components have short shelf lives, even if there are enough donations to cover immediate needs, banks ideally want to have enough around in case of a national or local emergency. Lastly, restrictions on blood donors mean that only 38% of all Americans can donate blood at any given time, but only 10% of the population donates blood every year.
What Makes Someone Ineligible to Donate?
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There are a lot of factors to determine someone’s eligibility to donate blood, including age, health, weight, visits to foreign countries, drug use, sexual history and recent body modifications. Donors may pass the pr-escreening tests and still be found ineligible when their blood is tested prior to transfusion. Some people who are deferred are only asked to wait a while before they attempt to donate, while others are told they can never donate. Most people who are deferred can return after a while and the number one reason for deferments is anemia.
The fact that men who have ever had sex with another man are banned from donating for life is a touchy subject in the blood donation world and there are valid arguments on each side of the discussion. Critics of the ban say the decision is based on outdated science and homophobia. They say that because each sample is tested for HIV, the risk is minimal. In 2006, the AABB, the Red Cross and America’s Blood Centers all pushed for a change in the policy, citing a study that suggested that allowing men who have had sex with another man to donate would only result in an additional case of HIV transmission once ever 33 years. They argue that because blood banks are in such desperate need of donations, this risk is worth it. The FDA rejected their proposal, saying the risk was not justified.
Those in favor of the ban point out that a study performed in the UK showed that allowing these men to donate would increase the risk of HIV entering the blood stockpiles by 500% and they argue that even if the ban is modeled to only prevent men who have engaged in homosexual activities in the last twelve months, the number would still increase 60%.
Critics argue that a gay man in a monogamous relationship carries a much lower risk of HIV than an intravenous drug user who has been clean for a year or a promiscuous straight man, both of who would be eligible to donate. The debate seems likely to continue for years, even if the ban is changed.
Donations and Transfusions in Other Countries
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If you’ve ever donated blood, you’ll notice that one of the inquiries involves lengthy stays in certain third world countries and the UK. If you ever wondered why the UK would be included in the list, it has to do with an untreatable degenerative brain disease known as Creutzfeldt–Jakob disease. It can be passed by blood and the UK has had such a problem with it that they ban recipients of their own country’s blood donations from donating blood.
Unfortunately, while verbal tests are performed prior to blood donations in all countries, many third-world countries can’t afford to actually test the blood for diseases such as HIV, syphilis and other dangerous illnesses after it is donated. That is why anyone who has received transplants in these countries cannot donate in the U.S. and many other countries.
Benefits to blood Donors
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If you’re one of those people that always wants to know how something will benefit them, there are a few reasons you should donate blood other than the fact that each donation can save up to three lives. First off, some businesses, including all companies in Italy, give you a paid day off for blood donation. Next, the blood centers will often guarantee you transfusion priorities if you are ever in need of blood. If you need something physical to motivate you though, keep in mind that many blood drives include prize drawings for really cool stuff (the Comic Con blood draw contest is awesome) and blood centers often give away free goodies and food.
If you know you can pass the screening test and that you have clean blood, please donate blood and help save lives.
Sources: Wikipedia #1, #2, WHO, New York Times, Web MD, Rue the Day