CLINICAL AND HEMATOLOGIC EFFECTS OF HYDROXYUREA IN CHILDREN WITH SICKLE-CELL-ANEMIA

Purpose: This open-label pilot study was' designed (1) to determine th e effect of hydroxyurea on the hemoglobin level in children with sickl e cell anemia, (2) to evaluate the toxicity of hydroxyurea, and (3) to assess any impact of hydroxyurea on the frequency of vaso-occlusive c rises (VOCs). Patients and methods: Ten children (group 1) with three or more VOCs of the extremities or two or more VOCs of the lungs (acut e chest syndrome) in the preceding 12 months, and five children (group 2) with hemoglobin levels less than 70 gm/L were treated with hydroxy urea in doses of 20 to 35 mg/kg per day. The frequency of VOCs before hydroxyurea therapy was compared with the frequency during therapy, an d the peak hemoglobin levels during hydroxyurea therapy were compared with the pretreatment values. Results: One patient in group 1 was remo ved from the study within 1 month because of nausea. Seven of the rema ining nine patients in group 1 had a decrease in the frequency of VOCs . The number of VOCs per patient-year for all 14 patients decreased fr om 2.5 before hydroxyurea therapy to 0.87 during hydroxyurea therapy, a decrease of 65% (p < 0.00001). Two of five patients in group 2 had a n increase in hemoglobin of 27 gm/L and 34 gm/L over the baseline. The median rise in hemoglobin was 19 gm/L (range, 7 to 37) for all 14 pat ients. Nine patients are still receiving hydroxyurea for a median peri od of 23 months (range, 18 to 59). Conclusions: Hydroxyurea decreases the severity of anemia in some patients, and it may decrease the frequ ency of VOC. Its short-term hematologic toxicity is minimal.