The importance of knowing your blood type is to prevent the risk of you receiving an incompatible blood type at a time of need, such as during a blood transfusion or during surgery. If two different blood types are mixed, it can lead to a clumping of blood cells that can be potentially fatal.
There are four main blood groups (types of blood) – A, B, AB and O. Your blood group is determined by the genes you inherit from your parents. Each group can be either RhD positive or RhD negative, which means in total there are eight main blood groups.
Antibodies and Antigens
Blood is made up of red blood cells, white blood cells and platelets in a liquid called plasma. Your blood group is identified by antibodies and antigens in the blood.
Antibodies are proteins found in plasma. They’re part of your body’s natural defences. They recognise foreign substances, such as germs, and alert your immune system, which destroys them. Antigens are protein molecules found on the surface of red blood cells.
There are four main blood groups defined by the ABO system:
- Blood group A – has A antigens on the red blood cells with anti-B antibodies in the plasma.
- Blood group B – has B antigens with anti-A antibodies in the plasma.
- Blood group O – has no antigens, but both anti-A and anti-B antibodies in the plasma.
- Blood group AB – has both A and B antigens, but no antibodies.
Receiving blood from the wrong ABO group can be life threatening. For example, if someone with group B blood is given group A blood, their anti-A antibodies will attack the group A cells. This is why group A blood must never be given to someone who has group B blood and vice versa.
As group O red blood cells don’t have any A or B antigens, it can safely be given to any other group. Blood group O is the most common blood group. Almost half of the population in several countries (48%) has blood group O.
How Blood Group Test is Performed
A blood sample is needed. The test to determine your blood group is called ABO typing. Your blood sample is mixed with antibodies against type A and B blood. Then, the sample is checked to see whether or not the blood cells stick together. If blood cells stick together, it means the blood reacted with one of the antibodies.
The second step is called back typing. The liquid part of your blood without cells (serum) is mixed with blood that is known to be type A and type B. People with type A blood have anti-B antibodies. People with type B blood have anti-A antibodies. Type O blood contains both types of antibodies.
The 2 steps above can accurately determine your blood type.
Rh typing uses a method similar to ABO typing. When blood typing is done to see if you have Rh factor on the surface of your red blood cells, the results will be one of these:
- Rh+ (positive), if you have this cell surface protein.
- Rh- (negative), if you do not have this cell surface protein.
Reasons why we should know our blood group
1. In a medical emergency where you need a blood transfusion urgently, it helps if your doctors know your blood type beforehand as this can save valuable minutes. If you get an incompatible blood type, it could cause your cells to clump, which is a life-threatening condition. It’s also helpful to know the blood types of your close family members so that if you or someone else needs blood in an emergency, the right family member can donate.
2. It is important to know if your blood type is positive or negative when you are pregnant, because if you are Rh negative and your baby is Rh positive (called Rh incompatibility), then your body may treat the baby as an allergen and could send antibodies through the placenta to attack your baby’s red blood cells. This is called haemolytic anaemia and can be life threatening for the baby.
The antibodies usually take a while to build up in your body, so it’s possible that they will only threaten your second pregnancy, but a blood test in early pregnancy will reveal your risk, and your gynae or clinic nurse will tell you what medication you need to take to prevent this.
3. If the blood bank needs a certain type of blood or if there is an emergency or low supply of a particular blood type, the National Blood Service will send out a call for donors of that blood type to come in and donate. If you know your blood type, you can respond to this call and your blood could save a life. In fact, one unit of blood can save up to three lives.
Some medical professionals even say that donating blood is healthy for you because it improves your cardiovascular health by reducing iron levels in your blood, and by promoting the creation of new red blood cells.
4. To predict your risk of certain diseases. It appears that certain blood types are associated more strongly with certain diseases. Examples :
- Blood clots – type AB blood.
- Heart disease – type AB blood.
- Fertility – type O women have been shown to carry fewer viable eggs.
- Stomach cancer – type A blood has a higher rate of incidence.
- Stress – type A blood has been shown to carry higher levels of the stress hormone, cortisol.
While blood type certainly isn’t a diagnostic tool, being aware of the higher risks associated with your type might make you more likely to take preventative action, or to spot the signs early.
5. It helps to determine the healthiest diet for you in particular. This is called a Blood Type Diet. This diet ensures that you eat the types of food recommended for your health as per your blood type. Dieticians claim that the food we eat reacts with our blood in ways that either boost our energy, encourage weight loss or even endorse weight gain.
Knowing what your blood type can help you know what kind of food to avoid if you wish to attain your body’s natural balance. For instance, if you are type O blood, your natural diet is suggested to consist of high-protein food with lean meats and less grain. Type A blood types are encouraged to focus on eating fruits, beans, and vegetables.
6. Believe it or not, your blood type tells you what kind of gym exercises you’ll react better to. Imagine not having to extend and contract your body in all the forms of exercises that exist in the world and just getting straight to the point? Well, that’s another benefit of knowing your blood type.