Influence of relative hypoparathyroidism on the responsiveness to recombinant human erythropoietin in hemodialysis patients

Background/Aim: It has been shown in a few studies examining small patient groups that high levels of intact parathyroid hormone (iPTH) were associated with a less efficient response to recombinant human erythropoietin (rHuEPO). However, the responsiveness to rHuEPO in hemodialysis (HD) patients with relative hypoparathyroidism remains undetermined. This study examines the responsiveness to rHuEPO in HD patients with relative hypoparathyroidism. Methods: We retrospectively studied 19 nondiabetic patients (mean age 44.3 ± 8.2 years, age range 29.4-55.6 years) treated with HD for chronic glomerulonephritis. Of the 19 patients, 8 (group A) had iPTH levels < 100 pg/ml for the preceding 6 months without administration of 1,25-(OH)₂-vitamin D₃. Eleven patients had iPTH levels > 100 pg/ml (group B). Hematocrit (Hct) and rHuEPO doses were recorded for statistical analysis. Results: In patients of groups A and B, the rHuEPO dose (U/kg/week) was 55.21 ± 16.23 vs. 84.08 ± 24.56 (p = 0.01); Hct (%) 33.29 ± 1.72 vs. 31.43 ± 2.98 (p = 0.67), and rHuEPO resistance index (weekly rHuEPO dose/Hct) 81.38 ± 16.64 vs. 155.63 ± 42.22 (p < 0.001). Furthermore, weekly rHuEPO dose and rHuEPO resistance index correlated positively with serum iPTH levels (R = 0.765, p < 0.001; R = 0.764, p < 0.001), whereas the Hct correlated negatively with serum iPTH levels (R = -0.400, p = 0.045). The alkaline phosphatase level (IU/l) was lower (50.46 ± 12.87 vs. 69.61 ± 20.68, p = 0.17) in group A. Conclusion: Our observations suggest that the lower the iPTH levels of chronic HD patients, even with relative hypoparathyroidism, the better the responsiveness to rHuEPO.