[A cold agglutinin disease, difficult to distinguish from paroxysmal cold hemoglobinuria]

A 58-year-old male started passing dark brown colored urine in January 2002. An annual medical examination in the same month revealed a mild anemia and an increased serum LDH level. Because of the instability of the data of his peripheral red cell count and hemoglobin concentration as measuring with a blood cell auto-analyzer, and also the hemolytic findings in a test tube at room temperature (25 degrees C), he was referred to our hospital. Laboratory data revealed Hb 11.2 g/dl, reticulocytes 73.1% (233,000/microliter), indirect-bilirubin 2.8 mg/dl, LDH 757 U/l, and hemosiderinuria, suggesting some intravascular hemolysis. The cold agglutinin titer was > 1,024, direct and indirect Coombs tests were both positive, and the Donath-Landsteiner antibody (D-L antibody) was initially assessed as false positive because of a high titer of cold agglutinin. He was finally diagnosed as having a cold agglutinin disease (CAD) with anti-I autoantibody. Serologic tests for syphilis and mycoplasma, and various virus tests were all negatives. After avoiding cold exposure, his symptoms, including hemoglobinuria, disappeared. However, during 9 months follow-up, he still showed a high titer of cold agglutinin. This case suggests that CAD should be considered when peripheral blood cell count data are unstable as assessed by a blood cell auto-analyzer.