What is blood, really?
Your blood is an amazing tissue (yes, it is a tissue!) that you can’t live without. Blood consists of a liquid part (plasma) that comprises about 55 percent of your blood, and most of the other 45 percent is comprised of red blood cells … lots of them. There are 150 billion red blood cells in an ounce of blood, and your body normally produces 17 million red blood cells per second. Your blood is constantly pumped throughout your body to feed and oxygenate your other cells, and it only takes 20-60 seconds for a blood drop to make an entire circuit.
What is a blood type?
Your blood type, like your eye or hair color, is determined genetically by inheritance patterns from your parents. About 45 percent of us are group O, 42 percent are group A, 10 percent are group B and 3 percent are group AB, but those numbers can vary a bit by nationality. For example, Latino-Americans and African Americans have a higher prevalence of group O than Caucasians. Asian-Americans have a higher prevalence of group B.
ABO and Rh types
Your ABO type describes the ABO antigens present on your red cells; Group A people have only A antigens, Group B people have only B antigens, Group AB people have both A and B antigens, and Group O people have neither A nor B antigens. In addition to your ABO antigens, you may have a D antigen present (85 percent of us do!) and you would be called D (or Rh) positive. The 15 percent who lack the D antigen would be called D (or Rh) negative. The D antigen was discovered during testing of Rhesus monkeys and was originally called “Rh antigen”. The term “Rh positive” and “Rh negative” still persists to describe the D antigen, and may be used interchangeably with the term “D positive” and “D negative.”
While most people are familiar with ABO and Rh types, there are actually many other recognized blood groups or blood types determined by antigens, (proteins) present on your red blood cells. Genetic testing that can test for more than 30 blood antigens can be performed using a very small droplet of blood from which DNA is extracted and tested.
Your ABO and Rh type is important for your physician to know if you are pregnant, to determine if your baby is at risk for Rh disease. This can happen when your Rh type is negative, and your infant’s type is Rh positive, and may cause very serious illness for the newborn. Your ABO and Rh type are also important for your transfusion service to know if you need a transfusion, so that your donor’s blood type can be ABO and Rh matched to your type.
Understanding blood type compatibility
There are specific ways in which blood types must be matched for a safe transfusion. The term “universal donor” is often used to indicate Group O donors; since they lack both the A and B antigens they are compatible with all blood types. Conversely, Group O recipients can only receive group O blood but Group AB recipients can receive blood from all other types.
Blood types and medical conditions
Blood types seem to have some relationship to certain diseases, but research is ongoing. The connections seem to be related to higher rates of inflammation common to some blood types. For example, people with blood types AB and B are at greater risk for heart disease, Groups AB and A are at greater risk for stomach cancer and ulcers, and Group AB people are at higher risk for cognitive problems as they age. Lest you think Group O folks fare better than the other types, think again-they are more affected by stress hormones, and, unfortunately, mosquitos have a preference for Group O blood! As research progresses, we might one day be able to tell a lot about a person’s health risks just from their blood type.
A call to donate!
Every two seconds someone in the U.S. needs blood. Approximately 36,000 units of red blood cells, 7,000 units of platelets and 10,000 units of plasma are needed every day, nationally. Unfortunately, although an estimated 38 percent of the U.S. population is eligible to donate blood at any given time, less than 10 percent of those eligible actually donate. When the low donor rate is coupled with regional issues (things like hurricanes or snowstorms) it is clear that maintaining an adequate blood supply can be an ongoing struggle. For example, on January 1, 2018 our Indiana blood suppliers had only 700 red cell units – less than a one-day supply – in their inventories, due to a decrease in donations as a result of low holiday donations and severe cold in our area. Every donor is important, but our suppliers really rely on their regular, loyal donors.
Do you want to make a difference? Donation is a quick 4-step process: registration, medical history/mini-physical, donation and refreshments. The process generally takes about an hour and 15 minutes from start to finish with the actual donation takes only 10-12 minutes. Donation is safe, it is confidential, it is a great gift that you can “pay forward” and it will make you feel good.
Learn more about making a blood donation here.
