Anemic patient lab results: IS 37 AHG SCR I 0 0 2+; SCR II 0 0 2+; AC 0 0 4+. Which clinical condition is consistent with these results?

• A. Cold agglutinin disease
• B. Warm autoimmune hemolytic anemia
• C. Alloimmune hemolysis due to transfusion
• D. Hereditary spherocytosis

Answer: (B)

The key idea is that this pattern points to an autoantibody causing autoimmune hemolysis, most classically a warm autoantibody. The activity at body temperature (reactivity at 37°C) means the antibody binds red cells under physiologic conditions. A positive direct antiglobulin test at the AHG phase confirms that red cells in the patient are coated with antibody (and possibly complement). The strongly positive autocontrol shows the antibody is reacting with the patient’s own red cells, which is characteristic of an autoantibody rather than an alloantibody directed at donor cells. The antibody screen being positive with screening cells I and II supports the presence of a broadly reactive antibody, again consistent with an autoantibody that binds common RBC antigens.

Cold agglutinin disease would typically show reactivity at lower temperatures (IS or 4°C) and usually a DAT positive for C3d only, not IgG, and the pattern would not include a strongly positive autocontrol at 37°C. Alloimmune hemolysis from transfusion often presents with a positive antibody screen but a negative autocontrol, since the antibodies are directed against non-self antigens and not against the patient’s own cells. Hereditary spherocytosis is a nonimmune hemolysis and would not produce these antibody-phase reactions or a positive autocontrol.

Thus, the findings align best with warm autoimmune hemolytic anemia, due to an IgG autoantibody that binds red cells at 37°C and causes targeted destruction.