Preservation of spleen and brain function in children with sickle cell anemia treated with hydroxyurea

Introduction. Chronic organ damage is an insidious process in patients with sickle cell anemia (SCA). Although hydroxyurea prevents acute vaso-occlusive events, its effects on the preservation of organ function remain undefined. Patients and Methods. We retrospectively reviewed our single institution experience with children with SCA treated with hydroxyurea for clinical disease severity, who had optional radionuclide liver-spleen (LS) and brain magnetic resonance imaging (MRI)/with angiography (MRA) performed before and during therapy. Studies were reviewed by pediatric radiologists blinded to treatment status. Demographic and laboratory predictors were modeled using logistic regression. Results. A total of 43 children had spleen function measured both at baseline and on therapy. After a median of 2.6 years (range, 0.2-8.6 years) of hydroxyurea at maximum tolerated dose (MTD), six patients (14%) completely recovered splenic function and two (5%) had preserved splenic function. These eight children had a greater hemoglobin (Hb) concentration on hydroxyurea therapy than those without splenic function (9.1 vs. 8.6 gm/dl, P=0.01). Of 25 children with brain MRI/MRA studies performed before initiating hydroxyurea and on therapy, 24 (96%) had no change in brain ischemic lesions compared with pre-treatment studies, after a median of 2.9 years of treatment. Conclusion. These retrospective data suggest that hydroxyurea at MTD possibly preserves spleen and brain function in children with SCA, and can even result in recovery of splenic function. Higher final Hb concentration during therapy is a significant laboratory predictor of improved splenic function.