Paricalcitol Treatment of Secondary Hyperparathyroidism in Hemodialysis Patients on Sevelamer Hydrochloride: Which Dialysate Calcium Concentration to Use?

Background: Optimal dialysate calcium concentration (DCa) has not been determined under less hypercalcemic vitamin D analogues and Ca-free phosphate (P) binders. Methods: Twelve hyperparathyroidic hemodialysis patients under sevelamer hydrochloride were treated with paricalcitol in three periods (A, B and C) under DCa of 3.5, 3 and 2.5 mEq/l, respectively, in a 3-way open-label randomized crossover study. Results: Serum parathyroid hormone decreased in all periods. Under DCa = 2.5 mEq/l, there was a need for longer treatment duration, higher paricalcitol doses and increased sevelamer doses for higher serum P levels. No differences in serum Ca were observed. Ca x P values followed P changes. Episodes of Ca x P > 55 mg(2)/dl(2) were more frequent in the C period. Conclusions: Under paricalcitol and sevelamer, serum parathyroid hormone decreased without Ca increase under any DCa. DCa of 2.5 mEq/l resulted in higher paricalcitol doses, increased serum P levels and more frequent high Ca x P episodes and may not be optimal with the new medications. Copyright (C) 2009 S. Karger AG, Basel