Reversal of adynamic bone disease by lowering of dialysate calcium

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 6.0+/-1.6 to 24.9+/-3.6 pM (P<0.0001). Bone formation rates, all initially suppressed, at 18.1+/-5.6 microm2/mm2/day rose to 159+/-59.4 microm2/mm2/day (P<0.05), into the normal range (>108 microm2/mm2/day). In the control group, nine patients completed the study. Their PTH levels did not increase significantly, from 7.3+/-1.6 to 9.4+/-1.5 pM and bone formation rates did not change significantly either, from 13.3+/-7.1 to 40.9+/-11.9 microm2/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.