Low and High Turnover Bone Disease in Continuous Ambulatory Peritoneal Dialysis: Effects of Low-Ca + Peritoneal Dialysis Solution

Calcium carbonate (CaCO3) is an effective phosphate (P04) binder in uremics, and its use reduces aluminum (AI) intake. By maintaining high serum Ca2+, it decreases serum parathyroid hormone (PTH) levels. Hypercalcemia, however, often limits the dosage.

In order to evaluate the effects of a low-Ca peritoneal dialysis solution (PDS) (1.25 mmol/L) on Ca metabolism, we studied the following in 12 continuous ambulatory peritoneal dialysis (CAPD) patients with hypercalcemia (6 with low PTH levels, low-turnover bone disease, group 1, and 6 with high PTH levels, high-turnover bone disease, group 2, documented by bone biopsies): serum Ca2+; serum PTH; bone morphology. The follow-up was 12 months.

Results show that in both groups within the third month there was a decrease in serum Ca2+. In group 1 serum PTH increased, reaching the norm, and In group 2 it further Increased exceeding the norm. Because In both groups serum Ca2+ was normal, It was possible to increase oral CaC03 (10.5±2.5 g/day) to control P04 levels and to stop AI gels. In group 2, In order to avoid the further rise of serum PTH, the low-Ca PDS was supplemented with 2 μg/day of 1,25(OH)2D3 (vitamin D3); this was followed by a reduction In serum PTH with no increase in Ca2+ and P04.

The use of low-Ca PDS may be useful In preventing hypercalcemia In CAPD patients treated with high oral doses of CaC03 and in improving low-turnover bone disease, while low-Ca PDS supplemented with vitamin D3 improves high-turnover bone disease.