1. ¹Department of Nephrology, St Margit Hospital, Budapest, Hungary
2. ²Department of Medicine, Veterans Administration Hospital and University of Washington, Seattle, Washington, USA
3. ³Division of Nephrology, Humber River Regional Hospital, Toronto, Canada

Correspondence: A Haris, Department of Nephrology, St Margit Hospital, 132 Becsi St, Budapest H-1032, Hungary. E-mail: agnesharis@hotmail.com

Received 21 July 2005; Revised 25 February 2006; Accepted 29 March 2006; Published online 12 July 2006.

Abstract

Adynamic bone disease (ABD) is increasingly recognized, especially in dialysis patients treated with oral calcium carbonate, vitamin D supplements, or supraphysiological dialysate calcium. We undertook this study to assess the effect of lowering dialysate calcium on episodes of hypercalcemia, serum parathyroid hormone (PTH) levels as well as bone turnover. Fifty-one patients treated with peritoneal dialysis and biopsy-proven ABD were randomized to treatment with control calcium, 1.62 mM, or low calcium, 1.0 mM, dialysate calcium over a 16-month period. In the low dialysate calcium group, 14 patients completed the study. This group experienced a decrease in serum total and ionized calcium levels, and an 89% reduction in episodes of hypercalcemia, resulting in a 300% increase in serum PTH values, from 6.01.6 to 24.93.6 pM (P<0.0001). Bone formation rates, all initially suppressed, at 18.15.6 m²/mm²/day rose to 15959.4 m²/mm²/day (P<0.05), into the normal range (>108 m²/mm²/day). In the control group, nine patients completed the study. Their PTH levels did not increase significantly, from 7.31.6 to 9.41.5 pM and bone formation rates did not change significantly either, from 13.37.1 to 40.911.9 m²/mm²/day. Lowering of peritoneal dialysate calcium reduced serum calcium levels and hypercalcemic episodes, which resulted in increased PTH levels and normalization of bone turnover in patients with ABD.