What is Direct Antiglobulin Test?
The more commonly used test, the Direct Coombs test, is used to test for autoimmune hemolytic anemia.
Purpose of Test
To help diagnose hemolytic anemia caused by autoimmune disease or induced by drugs; to investigate a transfusion reaction; to diagnose hemolytic disease of the newborn.
Test of Result Interpretation
If the DAT is positive, then there are antibodies attached to the RBCs. In general, the stronger the DAT reaction (the more positive the test), the greater the amount of antibody bound to the RBCs. The DAT detects the presence of the antibody, but it does not tell the doctor the cause or exact type of antibody. A patients medical history and a clinical examination is needed to determine if a positive DAT is due to a transfusion reaction, autoimmune reaction, an infection, a medication, or a baby-mother Rh incompatibility. A small percentage of the normal population will be DAT positive and not experience hemolytic anemia.
If a DAT is negative, then antibodies are not attached to RBCs and the signs and symptoms may be due to some other cause.
No preparation required