Procollagen type-I in the serum and dialysate of continuous ambulatory peritoneal dialysis patients

Procollagen-I carboxylterminal extension peptide (PICP) was determined in the serum and dialysate of 26 continuous ambulatory peritoneal dialysis (CAPD) patients and in the serum of 11 healthy controls. PICP serum levels were significantly higher in CAPD patients than in healthy controls (p < 0.001). There was no correlation between serum PICP levels and those of calcium, phosphorus, magnesium, alkaline phosphatase, osteocalcin, and intact parathyroid hormone (iPTH). Serum and dialysate levels of osteocalcin and iPTH showed a significant correlation (p < 0.001). The dialysate-to-serum PICP ratio in 21 patients was lower than 1.0. In the remaining 5 patients, however, the above ratio was higher than 1.0. We conclude that in CAPD patients serum PICP levels do not correlate with biochemical parameters of renal osteodystrophy. A dialysate-to-serum PICP ratio above 1.0 could implicate an increased local peritoneal fibroblastic activity and could be a useful marker of peritoneal fibrosis in CAPD.