Plasma and urine hydroxyurea levels might be useful in the management of adult sickle cell disease

Hydroxyurea (HU) is useful for treating sickle cell anemia because of its ability to reduce some of the severe clinical events such as painful crises and acute chest syndrome. It may also reduce the need for blood transfusions and frequent hospitalizations and reduce mortality. Nevertheless, no consistent recommendations regarding its therapeutic schedule are defined. Our aim was to improve and validate a high performance liquid chromatography (HPLC) technique to measure HU and to study HU levels in serum and urine of sickle cell anemia patients and relate this to treatment efficacy and compliance. Thirty- seven patients received 1,128 +/- 333 mg of HU per day (8.0 to 28.0 mg/kg/day). Plasma and/or urine were sampled and HU was measured using an HPLC method coupled with UV detection. We validated a specific, sensitive assay with good reproducibility and linearity, and showed a positive relationship between plasma HU concentrations and time elapsed between oral HU intake and sampling. We observed plasma HU concentrations were positively correlated with change in mean corpuscular volume (MCV) before and during the treatment. No correlation was obtained between HU concentration and Hb F level.