Two case studies and a review of paroxysmal cold hemoglobinuria.

Paroxysmal cold hemoglobinuria (PCH) is an acquired hemolytic anemia caused by immunoglobulin G (IgG) antibodies that sensitize red blood cells (RBCs) at cold temperatures by fixing complement to the RBCs causing intravascular hemolysis on rewarming. PCH usually appears in young children as recurrent high fevers, chills, and passage of red-brown urine. The diagnostic test for PCH is the Donath-Landsteiner test, an in vitro assay for biphasic hemolysis. Herein, we present 2 cases of PCH that occurred within 12 months of each other. We quickly diagnosed the second case and treated the patient successfully, in part due to our recognition of its characteristics based on the first case. PCH is a hemolytic anemia for which there is a specific diagnostic test; the timely recognition of this entity by physicians and laboratory staff will allow prompt, supportive therapy and will raise the odds of quick resolution of hemolysis.