[Diagnosis and clinical features of hemolytic uremic syndrome]

The hemolytic-uremic syndrome (HUS) is an acute disorder, characterized by the triad of microangiopathic hemolytic anemia, nephropathy and thrombocytopenia. The great majority of patients are children, usually under 4 years of age, although adults can be affected. The onset is abrupt and usually follows gastroenteritis or upper respiratory infection. Later, clinical manifestations based on the triad, such as pallor, jaundice, edema, hypertension and purpura soon develop. The urinary output is reduced and the urine may appear dark yellow or tea-colored. Laboratory tests of peripheral blood show severe hemolytic anemia associated with fragmented red blood cells and thrombocytopenia, usually below 50,000/microliters. The blood urea nitrogen, serum creatinine and lactate dehydrogenase concentrations are elevated. Proteinuria and microscopic hematuria, which are indicative of active glomerular damage are also seen. Profound understanding of these manifestations is sufficient to permit an early diagnosis of HUS.