Erythropoietic activity in patients with sickle cell anaemia before and after treatment with hydroxyurea

In this project we have prospectively studied the erythropoietic activity i n patients with sickle cell anaemia (SS) before and after treatment with hy droxyurea (HU). Some of the patients were enrolled in a double-blind placeb o controlled trial of HU in patients with SS and others were enrolled in an open label study. Determinants of erythropoietic activity included the ret iculocyte count, red blood cell (RBC) survival by the Cr-51 method, plasma Fe-59 clearance, plasma iron turnover (PIT), erythron transferrin uptake (E TU), RBC production/destruction rate, and RBC Fe utilization, Therapy with HU increased the mean corpuscular volume (MCV), haemoglobin (Hb)F, RBC surv ival and t(1/2) (59)Pe clearance; it decreased the reticulocyte count, the white blood cell (WBC) count, ETU, and the PIT. Most of the changes in para meters of erythropoiesis could be explained by the increase in Cr-51 RBC su rvival after therapy with HU. Together the data showed that in selected pat ients the net effect of HU on Hb level was a function of the difference bet ween the suppressive effect of HU (decreased RBC production) and the increa se in RBC survival. In the majority of patients who responded to HU, there was a preferential effect on RBC survival.