Heinz-body hemolytic anemia associated with phenazopyridine and sulfonamide

A 27-year-old white woman developed Heinz-body hemolytic anemia following multiple courses of oral phenazopyridine and trimethoprim-sulfamethoxazole. Her diagnosis was supported by the finding of bite cells on peripheral blood smear. The patient's rapid recovery and reversal of abnormal laboratory parameters were consistent with an acquired hemolytic disorder. This case should sensitize the clinician to the development of drug-induced oxidative hemolysis, its clinical features, and its reversibility. It is also important that the clinician recognize those drugs capable of causing this disorder and appreciate the methods available to establish the diagnosis.