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Hydroxyurea has, for the past twenty-five years, been the only available therapy to reduce manifestations of sickle cell anemia. Despite solid data showing its effectiveness and safety, the prescription of hydroxyurea was long restricted to the most severe patients and only introduced after the recurrence of acute vaso-occlusive events. Given that sickle cell anemia remains associated with premature mortality in adults and a very high morbidity rate—involving severe and chronic acute complications in children, and pain and chronic organ damage in young adults—hydroxyurea treatment should be offered from infancy in order to prevent complications. Dosing (usually 20 to 35 mg/kg/d) should aim for maximal clinical and biological efficacy, and target absolute neutrophil counts of under 2.5 G/L. For this strategy to have an impact on children’s health, the commitment of parents, as well as young patients, to daily hydroxyurea treatment is crucial, and monitoring of this compliance is a key issue for health-care providers.