Abstract
Hemoglobin F (HbF) is an effective inhibitor of HbS polymerization. Hydroxyurea (HU) is used to increase HbF synthesis and improve the clinical course of sickle cell disease (SCD) patients. We studied a series of laboratory parameters concerning HbF production and reticulocyte response, and compared data between two groups: 1) 13 SCD patients treated with HU, and 2) 33 untreated SCD patients. Higher values of Hb concentration, mean cell volume (MCV), mean cell hemoglobin (MCH), mean reticulocyte volume (MRV), HbF concentration, percentage of Fβcells, and amount of HbF/Fβcells were observed in the treated group of patients. There was no correlation between Hb and HbF elevations. The reticulocyte count, immature reticulocyte count, mean fluorescence index (MFI), and neutrophil count were significantly lower in treated patients. Taken together, these findings suggest that a decreased hemolytic process occurred in patients undergoing HU treatment. There was a significant correlation between MCV and HbF, between MRV and HbF, and between MRV and Fβcell in patients taking HU. These data indicate that macroreticulocytes correspond to Fβreticulocytes, and that an increase in MRV in SCD patients using HU may be an indirect signal of Fβcell production. The concentration of HbF/Fβcells was higher in patients treated with HU, but this increase apparently was independent of Fβcell production. Reticulocyte (RTC) parameters, as assessed by hematological analyzers, may be useful for following erythropoietic changes in patients receiving HU, and can indirectly indicate HbF and Fβcell production induced by HU therapy. J. Clin. Lab. Anal. 17:66β72, 2003. Β© 2003 WileyβLiss, Inc.