A smear showing RBC agglutination is most likely to be observed in which condition?

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Multiple Choice

A smear showing RBC agglutination is most likely to be observed in which condition?

RBC clumping on a smear points to antibodies that bind and cross-link red cells at cooler temperatures, a hallmark of cold agglutinin disease. In this condition, IgM antibodies against red cells bind in the periphery (where cooler temperatures prevail) and bridge cells together, producing visible agglutination on a smear. When the sample or body warms to normal temperature, complement is activated and hemolysis can occur, often with the direct antiglobulin test showing C3d rather than IgG. This pattern differs from the other listed conditions: sickle cell disease shows misshapen sickled cells rather than clumped cells; G6PD deficiency features oxidative damage with Heinz bodies and bite cells; iron deficiency anemia shows microcytosis and hypochromia without RBC aggregation. Therefore, RBC agglutination on smear best fits cold agglutinin disease.

RBC clumping on a smear points to antibodies that bind and cross-link red cells at cooler temperatures, a hallmark of cold agglutinin disease. In this condition, IgM antibodies against red cells bind in the periphery (where cooler temperatures prevail) and bridge cells together, producing visible agglutination on a smear. When the sample or body warms to normal temperature, complement is activated and hemolysis can occur, often with the direct antiglobulin test showing C3d rather than IgG. This pattern differs from the other listed conditions: sickle cell disease shows misshapen sickled cells rather than clumped cells; G6PD deficiency features oxidative damage with Heinz bodies and bite cells; iron deficiency anemia shows microcytosis and hypochromia without RBC aggregation. Therefore, RBC agglutination on smear best fits cold agglutinin disease.

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