RenaGel efficacy in severe secondary hyperparathyroidism

Abstract

Background: Haemodialysis patients frequently have simultaneous hypercalcemia and hyperphosphatemia, posing a therapeutic dilemma for the traditional calcium--and aluminum--based binders. RenaGel (sevelamer hydrochloride) is an effective phosphate binder without changes in serum calcium or aluminum levels. However being an expensive medication it is currently used mainly for patients with moderate to severe secondary hyperparathyroidism. However most of the previous studies have not included patients with severe secondary hyperparathyroidism.

Methods: Our purpose is to determine RenaGel binder efficacy in haemodialysis patients with severe secondary hyperparathyroidism. As a secondary purpose we have followed the variations of parathyroid hormone, serum calcium, serum lipids [low- and high-density lipoprotein cholesterol, triglycerides and Lipoprotein(a)], uric acid and bicarbonate. All phosphate binders previously used were suspended one week before RenaGel prescription. Our study included 18 adult haemodialysis patients, with PTHi of 810 +/- 330 pg/ml after the "pre-treatment" washout. The binder was administered during 12 weeks, beginning with a mean dose of 2.4 +/- 0.4 g daily and adjusted to obtain serum phosphorus under 6.5 mg/dl (at the end of the study, the mean RenaGel dose was 2.8 +/- 0.6 g daily.

Results: The mean changes after RenaGel in serum phosphorus was -0.7 +/- 1.5. mg/dl (P < 0.05), in serum calcium was 0.5 +/- 1.0 mg/dl (P < 0.05) and in calcium x phosphate product of -4.0 +/- 12.4 mg/dl (P = NS). "Post-treatment" the PTHi levels remained stable (820 +/- 360 pg/ml vs 810 +/- 330) but serum alkaline phosphatase increased (14.3 +/- 14.4 U/l; P < 0.01). LDL cholesterol serum levels decreased by -35 +/- 10 mg/dl (P < 0.01), HDL cholesterol showed a trend to increase (3.0 +/- 8.1 U/l; P = NS), triglycerides decreased by 38 +/- 56 mg/dl (P < 0.05) and Lipoprotein(a) remained stable. Serum albumin increased by 0.1 +/- 0.2 g/L (P < 0.05), uric acid decreased -0.8 +/- 1.2 mg/dl (P < 0.05) and bicarbonate remained unchanged.

Conclusions: RenaGel is an effective phosphate binder, even in haemodialysis patients with severe secondary hyperparathyroidism. The lipid profile improved with the treatment, with the exception of Lipoprotein(a) stabilization. Selection of patients with severe secondary hyperparathyroidism at the beginning of RenaGel disposal, for economic reasons is debatable, but could be correct.