Enhancement of ionized calcium and 1,25-dihydroxycholecalciferol loss from peritoneal fluid during peritonitis in patients treated with continuous ambulatory peritoneal dialysis.

This study was to evaluate whether peritoneal loss of vitamin D metabolites during peritonitis leads to more depletion of 1,25-hydroxycholecalciferol [1,25(OH)2D3] and 25-hydroxycholecalciferol [25(OH)D] in continuous ambulatory peritoneal dialysis (CAPD) patients, especially in the high peritonitis occurrence group (HPOG). A series of ionized calcium, pH values, 1,25(OH)2D3 and 25(OH)D levels in dialysate during peritonitis were studied in 30 CAPD patients. In addition, bone mineral content (BMC) was determined during peritonitis. On the basis of peritonitis occurrence, 14 patients were in the low peritonitis occurrence group (LPOG) and 6 patients in the HPOG. Increase in peritoneal loss of ionized calcium, 1,25(OH)2D3, 25(OH)D and a decrease of pH value in dialysate may appear in the early period of peritonitis in both groups. When peritonitis occurs too frequently in a short period, the peritoneal membrane function cannot recover completely. Frequent peritonitis may impair peritoneal function and cause persistent loss of calcium. 1,25(OH)2D3 amd 25(OH)D loss is also higher in the HPOG than in the LPOG. The persistent loss of calcium, low plasma vitamin D levels and increased parathyroid hormone level with hyperparathyroidism in the HPOG are the important factors contributing to renal osteodystrophy. The lower BMC in the bone study confirmed this. Therefore, adequate calcium and vitamin D supplementation is necessary in the HPOG.