Paroxysmal nocturnal hemoglobinuria presenting as recurrent hemolytic uremic syndrome

Paroxysmal nocturnal hemoglobinuria (PNH) may present with acute anemia, thrombocytopenia and, if hemoglobin nephropathy or dehydration is present, azotemia. Thus PNH may be confused with the hemolytic uremic syndrome (HUS). Recurrent episodes, though common in PNH, are unusual in HUS. A positive acid hemolysis test can be used to differentiate between the two diseases.