Maximum urine concentrating ability in children with Hb SC disease: Effects of hydroxyurea

Studies in adults with Hb SC disease suggested that hydroxyurea reduced hem olysis and increased red cell hydration. Because increased hydration should diminish the polymerization tendency of Hb S we hypothesized that hydroxyu rea might repair the urine concentration defect of HbSC disease, Eight Hb S C disease patients, aged 10 to 17 years, were given hydroxyurea daily, Maxi mal urine concentrating ability following overnight fasting and after subcu taneous arginine vasopressin (dDAVP), blood counts, and cell Volumes were o bserved for 12-15 months. All patients had impaired urine concentrating abi lity prior to hydroxyurea treatment and failed to increase their ability to concentrate urine following treatment (maximum urine concentration after a n overnight fast and dDAVP, 520-530 mOsm), Mean corpuscular volume (MCV) an d reticulocyte MCV increased after administration of hydroxyurea, and the r eticulocyte count and ratio of red cell hemoglobin to reticulocyte hemoglob in fell but there was little change in PCV. Hb F increased substantially in 2 patients but showed little change in the remaining patients. There was n o evidence that hydroxyurea was associated with increased urine concentrati ng ability in children with Hb SC disease. These results may reflect irreve rsible renal medullary damage prior to beginning treatment or insufficient intensity or duration of treatment, Am. J. Hematol. 64:47-52, 2000. (C) 200 0 Wiley-Liss, Inc.