Long-Term Effect of Different Dialysate Calcium Concentrations on Parathyroid Hormone Levels in Hemodialysis Patients

The appropriate dialysate calcium concentration (D[Ca]) for hemodialysis (HD) therapy has not yet reached a consensus. We have conducted a prospective control study for five years on the effects of different D[Ca] on serum intact parathyroid hormone (iPTH) levels. Patients were divided into three groups receiving different D[Ca] therapies: the low-Ca (D[Ca]?=?2.5 mEq/L; N?=?96), mid-Ca (D[Ca]?=?3.0 mEq/L; N?=?121), and high-Ca (D[Ca]?=?3.5 mEq/L; N?=?82) groups. After five years' study, only 41 patients in the low-Ca group, 34 in the mid-Ca group, and 32 in the high-Ca group completed the study. The results demonstrated that serum corrected calcium concentrations were significantly lower in the low-Ca group compared with other groups in years 3 and 4, although the products of corrected calcium time phosphate did not show difference between each group.^Δserum alkaline phosphatase (^ΔAlk-p) to baseline levels increased significantly after the fourth year in all three groups (p < 0.05). Serum ^Δ iPTH only increased significantly after the fourth year in the low-Ca group (p < 0.05) but not in the other groups. There were no significant differences in the extent of ^ΔAlk-p and ^ΔiPTH between the groups. Cox proportional methods also showed no difference in cumulative survival between the groups. In conclusion, our results demonstrate that compared with the other two groups of D[Ca], long-term use of D[Ca] of 2.5 mEq/L was associated with relatively lower serum calcium concentration. Perhaps this was related to a greater extent of iPTH concentration elevation after five years.