Which finding best confirms autoimmune hemolytic anemia?

• A. Direct Coombs (DAT) test positive with spherocytes on smear and reticulocytosis
• B. Indirect Coombs test positive alone
• C. Low LDH with normal hemolysis markers
• D. Normal haptoglobin and unconjugated bilirubin

Answer: (A)

Detecting immune-mediated destruction of red blood cells hinges on the direct antiglobulin test. The direct Coombs (DAT) test shows antibodies or complement attached to the surface of red blood cells in the patient, which is the in vivo sign of autoimmune hemolysis. When the DAT is positive and the smear shows spherocytes with reticulocytosis, it indicates that red cells are being targeted by autoantibodies and the bone marrow is compensating by producing more reticulocytes. The indirect Coombs test looks for antibodies in the serum, but it confirms nothing about ongoing destruction in the body, so it does not by itself confirm autoimmune hemolysis. Hemolysis typically shifts labs toward higher LDH and unconjugated bilirubin with lower haptoglobin, so normal haptoglobin and bilirubin would not fit the picture of active immune hemolysis.