Does parathyroid hormone affect erythropoietin therapy in dialysis patients?

OBJECTIVE

The objective of this study was to assess the response to recombinant human erythropoietin (rHuEPO) during treatment of anemia in dialysis patients with hyperparathyroidism.

SUBJECTS AND METHODS

A total of 118 patients with stage 5 renal failure on dialysis therapy were selected for this study. Anemia was treated with rHuEPO. Laboratory data for each patient included intact parathyroid hormone (iPTH), hemoglobin (Hb), hematocrit (Hct), blood urea nitrogen, serum creatinine, calcium, phosphate, and alkaline phosphatase. Patients with iPTH >32 pmol/l were considered hyperparathyroid. Erythropoietin resistance index (ERI) was expressed as the ratio of weekly rHuEPO dose/Hct level.

RESULTS

Of the 118 patients, 83 (70.3%) were on hemodialysis (HD) and 35 (29.7%) were on continuous ambulatory peritoneal dialysis (CAPD). Sixty-three patients (64.3%) with iPTH >32 pmol/l had Hb <11 g/dl, while 34 (54.8%) with iPTH <32 had Hb >11 g/dl (p = 04). Thirty-three (56%) patients with iPTH >32 pmol/l had hemocrit <33%, while 38 (61.3%) with iPTH <32 had hemocrit <33% (p = 0.4). The median value of weekly rHuEPO dose in HD patients (12,000 units) was significantly higher in comparison with CAPD patients (6,000 units; p < 0.0001). ERI was significantly higher in HD than CAPD patients with iPTH <16 pmol/l (p = 0002) as well as with patients with 16-32 pmol/l (p = 0.012).

CONCLUSIONS

CAPD patients showed a reduced requirement for rHuEPO and better control of anemia compared with HD patients. ERI was also lower in CAPD than in HD patients. Hyperparathyroidism is a parameter predictive of rHuEPO hyporesponsiveness in dialysis patients.