For what purpose is agglutination testing primarily used?

Agglutination testing is primarily used to determine blood types because this method relies on the clumping (agglutination) of red blood cells in the presence of specific antibodies. When blood is mixed with anti-A or anti-B antibodies, the resulting reaction indicates the presence or absence of A or B antigens on the surface of red blood cells, thereby identifying an individual's blood type. This is crucial for transfusion medicine, organ transplantation, and prenatal testing, as knowing a patient's blood type helps prevent serious transfusion reactions.

The other options do not align with the primary application of agglutination testing. Measuring glucose levels typically involves biochemical assays rather than agglutination. Analyzing enzymes usually requires enzyme-linked immunosorbent assays (ELISA) or similar techniques for quantification. Counting blood cells is performed using hemocytometers or automated cell counters rather than through agglutination methods. Thus, the unique mechanism of agglutination testing makes it specifically suited for blood type determination.