[Congenital xerocytosis].

Hereditary xerocytosis is a genetic disease inherited as an autosomal dominant trait and is a rare cause of hemolytic anemia. It is caused by abnormal erythrocyte membrane permeability: monovalent cation pump activity is increased and the Na/K pump cannot compensate for the K lost. As a consequence, xerocytes dehydrate, becoming rigid and sensitive to metabolic stress and oxidation. Morbility depends on the severity of the hemolytic anemia. Periodic episodes of jaundice are common during mild infections; most patients remain asymptomatic but experience mild-to-moderate hemolytic anemia, which is generally well compensated. The diagnostic clues are a markedly increased flow through the Na/K pump with a decrease in total intracellular cation content and subsequent red cell dehydration. Treatment is based on monitoring for eventual complications and careful observation during infections, which may worsen the anemia. Splenectomy is not useful and for some authors may even be contraindicated. The prognosis is generally very good. We report the case of a patient with episodes of hemolytic anemia during intercurrent infections and positive diagnostic tests for hereditary xerocytosis.