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The Importance of Knowing Your Blood Type: 3 Methods to Identify Yours
Knowing your blood type is essential for your health. Here's how to figure it out with clinical tests, home testing kits and more.
Macy MeyerEditor I
Macy Meyer is a N.C. native who graduated from UNC-Chapel Hill in 2021 with a B.A. in English and Journalism. She currently resides in Charlotte, N.C., where she has been working as an Editor I, covering a variety of topics across CNET's Home and Wellness teams, including home security, fitness and nutrition, smart home tech and more. Prior to her time at CNET, Macy was featured in The News & Observer, The Charlotte Observer, INDY Week, and other state and national publications. In each article, Macy helps readers get the most out of their home and wellness. When Macy isn't writing, she's volunteering, exploring the town or watching sports.
ExpertiseMacy covers a variety of topics across CNET's Home and Wellness teams, including home security, smart home tech, fitness, nutrition, travel, lifestyle and more.Credentials
Macy has been working for CNET for coming on 2 years. Prior to CNET, Macy received a North Carolina College Media Association award in sports writing.
You might not know your blood type, and that can be a problem when it comes to your overall wellness. No matter your age or health, it's crucial to know whether you're type A, B or O. Having this piece of information can help you in an emergency situation or make filling out certain forms a little easier.
For example, I was recently filling out a volunteer application and was asked to provide my blood type. Luckily, I knew off the top of my head that I'm type O-positive, but I wanted to find documentation to confirm that. I called my mom to see if blood type is listed on my birth certificate -- no luck. I checked my physician's health portal -- also no luck.
So how does someone figure out their blood type if they don't already know it?
If you have no clue what your type is, you're not alone. According to a 2019 CBS News poll, only 66% of Americans reported knowing their blood type. Considering blood type can be vital to understanding your health, including your heart health -- and saving your life in an emergency -- it's important to know what kind of blood courses through your veins. The good news is finding out your blood type is relatively simple and you have options. Below are three easy ways to find out your blood type.
Blood type is categorized into one of these eight groups: A-positive, A-negative, B-positive, B-negative, O-positive, O-negative, AB-positive and AB-negative. But what determines blood type and what does that blood type mean?
Blood types are determined by antigens -- a substance that triggers an immune response -- on the surface of red blood cells. There are ABO antigens, which designate ABO blood types. This is determined by the ABO gene. For example:
Type A blood type has the A antigen
Type B blood type has the B antigen
Type AB blood type has both the A and B antigen
Type O doesn't produce any A or B antigen
There are also Rhesus (Rh) antigens, which determine if blood is "positive" or "negative." If you have Rh proteins on the surface of your red blood cells, you are Rh positive. If you don't have Rh proteins on the surface of your red blood cells, you have negative blood.
One of the easiest and most effective ways to determine blood type is to have your doctor perform a test. A professional will draw blood and then perform two tests on the blood sample: forward typing and reverse typing.
During forward typing, the blood sample is mixed with antibodies against type A and B blood. Based on whether the blood cells stick together when mixed with the antibodies, your blood type can be determined from there. If your blood cells stick together when mixed with antibodies against type B blood, you have type B blood. If your blood cells stick together when mixed with antibodies against type A blood, you have type A blood.
To confirm the result, the next step is reverse typing, meaning the blood sample without red blood cells -- called a serum -- is mixed with type A and type B blood cells. Type A blood will have antibodies against Type B blood in the sample and type B blood will have antibodies against Type A blood. Type O blood will contain antibodies against Type A and Type B. So, if sticking occurs when the serum is mixed with type B blood cells, you have type A blood, and if sticking occurs when the serum is mixed with type A blood cells, you have type B blood.
I recommend calling your doctor's office to see what a blood type test costs out-of-pocket and if it's covered by insurance.
2. Donate blood
This is an easy -- and free -- way to determine blood type, but results are not immediate.
If you donate to a blood drive, you can simply ask the staff about your blood type. Blood usually is not tested right away, so it may take up to a few weeks to get results.
3. At-home blood test
At-home tests are relatively straightforward. You will usually start by wiping your finger with an alcohol wipe and then be required to prick your finger with a disposable lancet to draw blood. Then, you will wipe blood on the provided card. Depending on how the blood dries, clumps or spreads, you will be able to compare your blood stain to a results card. Within minutes, you'll be able to determine which blood type you are.
The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.