2. Duration of Therapy

There is no basis for limiting long-term therapy of sickle cell disease; however, treatment with hydroxyurea requires monitoring of blood counts every 2 weeks due to the risk of myelosuppression. Hydroxyurea should be discontinued until hematologic recovery if blood counts reach toxic ranges defined as: neutrophils less than 2,000/mm3, platelets less than 80,000/mm3, hemoglobin less than 4.5 g/dL, or reticulocytes less than 80,000/mm3 if hemoglobin is less than 9 g/dL. Younger patients with lower baseline counts may safely tolerate an absolute neutrophil count down to 1,250/ mm3 [1-3].