Blood Type Testing Overview
Reviewed By: Dr. Kurt Kloss, MD
Last Reviewed Date: Feb 14, 2019
Last Modified Date: Feb 14, 2019
Published Date: Jul 29, 2017
What is My Blood Type?
Blood typing is a means used to medically categorize a person's specific type of blood. Blood type is determined by looking at the makeup of red blood cells to find out whether or not certain proteins, called antigens, are present. Here we'll go over the details of blood typing, including how blood type is determined, what the different blood groups are and why blood typing is important, as well as how you can get the answer to the question “What is my blood type?”
Why does blood type matter?
The primary reason that blood type matters is that not all blood types are compatible. This becomes important in many medical situations. For instance, a person who needs a transfusion must be given blood that is compatible with their blood type, since blood that is not can trigger a dangerous immune system response that can lead to serious health complications and, in some cases, death. Transplant patients must be given organs from donors with compatible blood types to reduce risk that their bodies will reject their new organ. Incompatible blood types in a mother and unborn child can have life-threatening consequences without appropriate treatment.
Another reason blood type matters is that knowing yours can help you take better care of your health. That's because your blood type can make you more prone to certain health issues. For instance, studies have shown that people with type AB blood have a higher risk of heart disease as compared to other blood types, while type O people are more likely to get ulcers. Knowing your blood type and the health risks associated with it can help you and your healthcare provider create a preventive care plan tailored to those specific needs.
How is blood typing done?
Blood is classified into types based upon its blood group and Rh factor. This is done by evaluating certain markers, called antigens, on the surface of red blood cells. The most important antigens in establishing blood type are blood group antigens, or ABO, and the Rh antigen. These are evaluated via blood tests, called ABO and Rh tests. The ABO test determines which type of blood a person has in terms of four blood groups, which are A, B, AB or O. This is done according to the antigens found on the surface of red blood cells as follows:
- The A antigen – The presence of this antigen means that your blood is type A.
- The B antigen – Having the B antigen means you have type B blood.
- Both A and B antigens – The presence of A and B antigens makes your blood type AB.
- Neither A nor B antigens – The absence of both A and B antigens means that your blood is type O.
The Rh test is the next step in determining individual blood type. This test determines whether or not Rh antigens, also commonly called Rh factors, are present, further breaking down blood types into positive or negative categories as follows:
- If your red blood cells carry the Rh antigen, you have Rh-positive blood.
- If there is no Rh antigen present, your blood is Rh-negative.
What are the different blood types?
Both ABO and Rh blood test results are used to classify blood into types. These are:
- A-positive (A+)
- A negative (A-)
- B-positive (B+)
- B-negative (B-)
- AB-positive (AB+)
- AB-negative (AB-)
- O-positive (O+)
- O-negative (O-)
How do we get our blood type?
Your blood type is a genetic trait passed down from your parents, rather like the color of your hair and eyes. Basically, you get one gene related to blood group from each parent, as well as one from each related to Rh factor, and the combination of the genes donated by each parent determine which blood type you will have. This genetic determination of blood type is the reason that blood type testing has, over the years, often been used to help determine the paternity of children – although blood type comparisons have typically proven to be more useful in ruling out potential fathers than in proving paternity.
How to get blood type testing and what to expect
If you would like to know what your blood type is, you need blood type testing. This can be done through your healthcare professional, which will typically entail making an appointment for an office visit, requesting testing and, should your provider agree to order your test, having a blood sample drawn and sent to a laboratory to have ABO and Rh tests run. Getting your results may mean another office visit, although some providers will deliver them via telephone, email or regular mail.
Alternatively, you can use Health Testing Centers, to purchase your tests directly. First, you would choose the tests you need, then order them online or over the phone. You would then go to a participating lab location near you, where you would have your blood sample drawn by a nurse or lab technician. That sample will be tested at that same lab and your blood type results sent directly to you, generally within a day or two of your blood-draw appointment. This is typically the faster and more economical choice, since it saves you time and money spent on office visits, as well as the time you would spend waiting for your healthcare provider's office to pass your test results along to you.
Lab Tests (A-Z)
Learn your blood type. Test determines blood group (A, B, AB, or O) and Rh type (positive or negative)