Which test would help diagnose anemia?

The hematocrit test is specifically designed to measure the proportion of blood volume that is occupied by red blood cells. This test is crucial for diagnosing anemia because it provides information about the concentration of red blood cells in the bloodstream. In cases of anemia, the hematocrit level is often lower than normal, indicating a reduced capacity for the blood to carry oxygen, which is a central concern in the diagnosis of this condition.

In contrast, a blood type test primarily determines the ABO and Rh blood types for transfusion purposes and does not provide relevant information about red blood cell counts or hemoglobin levels. An allergy test focuses on identifying specific immune reactions to allergens and has no direct correlation to red blood cell health or anemia. DNA analysis is used for genetic testing and does not serve as a diagnostic tool for anemia in a clinical setting. Therefore, the hematocrit test stands out as the appropriate choice for diagnosing anemia due to its direct relation to red blood cell levels in the body.