The Direct Coombs test is primarily used to diagnose which condition?

The Direct Coombs test is primarily used to diagnose hemolytic anemia, which occurs when the immune system mistakenly attacks and destroys red blood cells. This test detects antibodies that are bound to the surface of red blood cells, indicating an autoimmune reaction. In conditions such as autoimmune hemolytic anemia, the body produces antibodies that can attach to its own red blood cells, leading to their destruction.

In contrast, the other options do not pertain directly to the purpose of the Direct Coombs test. For instance, cardiovascular disease primarily involves issues related to the heart and blood vessels, while mononucleosis typically concerns viral infections affecting white blood cells. Rheumatoid arthritis is an autoimmune condition affecting the joints, but it does not specifically relate to the hemolytic process that the Coombs test is designed to detect. Therefore, the Direct Coombs test is specifically relevant to hemolytic anemia causes, reflecting its role in identifying the underlying immune response responsible for the disease.