The blood of two different people is seldom the same. A blood type test is usually done to check the blood type of the person before blood transfusion is commenced. It is also often done to check the blood type of a pregnant woman.
Human blood has its own signature and is differentiated according to the different markers that are present on the red blood cells. The blood chemistry may often be studied for DNA analysis and to ascertain if two people are related by blood. The antigens in the blood, or the so called markers, are used to find out the blood type. There are two antigens, one is the ABO blood type and the other is the Rh factor. These are therefore the most common blood type tests.
The ABO tests categorize people into four different blood groups. A, B, AB, and O. All these have different markers on the red blood cells. The A antigen make a person belong to the blood group A. In the A type blood, the antibodies of the plasma fight against the B antigens. Similarly, in the B type blood, the blood plasma fight against the A antigen. Therefore, the type A and B blood groups can receive blood only from people who have the same blood group.
When the both A and B antigens are absent in the blood, the blood group is O type. The plasma of such blood group fights both A and B antigens. The A and the B antigens are both present in certain blood groups. This blood group is known as the AB group. For transfusion of blood, it is essential to determine the blood type. If the wrong blood type is transfused, the incompatible blood is destroyed by the host’s antibodies. Such a transfusion reaction can cause illness and sometimes even death.
Type O-negative blood is called the universal donor type because it does not have either of the A and B antigens. Similarly, since AB-positive blood type has both A and B antigens, it is known as a universal recipient type.
Lately, not only are the blood types matched for transfusion purposes, but naturopathy has made claims that each blood group should have a different blood type diet, specific to their own blood type. This, they claim, is necessary for maintaining good health and averting many diseases and disorders.
A lot of blood type personality tests have also come up which claim that the blood type and the blood chemistry is an important factor in determining the personality of a person.