DECREASING RETICULOCYTE COUNTS ASSOCIATED WITH DECLINING POST-DOSE ERYTHROPOIETIN PLASMA-LEVELS IN ANEMIA OF PREMATURITY

A prospective sequential, multicentre trial was conducted to determine the association between erythropoietin (EPO) plasma levels and the er ythropoietic response to recombinant human erythropoietin (r-HuEPO) du ring long-term treatment of premature infants. Twenty-nine infants, ge stational ages 26-34 weeks and postnatal ages more than 14 days, recei ved 600 IU r-HuEPO per kg per week divided into three doses subcutaneo usly for haemoglobin levels less than 120 g/l or haematocrit less than 36% over a period of 4 weeks. Eight additional patients were studied for a total of 10 weeks. EPO plasma concentrations and haematologic pa rameters were measured prior to the onset of treatment and at 2-weekly intervals thereafter. Treatment with r-HuEPO resulted in a median inc rease in corrected reticulocyte counts of 2.5% (range 0.2-4.6%) above patient's baseline, thereafter a decrease was observed. In the 8 patie nts followed for 10 weeks reticulocyte counts declined significantly d uring weeks 6-10 when compared with the first 4 weeks (p < 0.005). Med ian 72-hour post-dose EPO plasma levels increased significantly (p < 0 .0001) to 57.3 mU/ml (range 5.0-160) above patient's baseline after th e first injection, but declined progressively thereafter until they ap proached baseline values at week 10. Conclusion: R-HuEPO treatment aft er the first month was associated with a decrease in post-injection pl asma levels and a decrease in erythropoietic response. This decrease i n erythropoietin's efficacy and the decline observed in post-dose EPO plasma levels may be causally related.