Changes of serum bone markers in CAPD and hemodialysis patients

A non-invasive method for evaluation of high-turnover and low-turnover bone diseases is the measurement of certain important serum bone markers such as osteocalcin, procolagen-I-propeptide, dioxypiridinoline, hydroxyproline and alkaline phosphatase. Renal osteodystrophy (ROD) in pre-dialysis and dialysis patients, is manifested in 3 forms: high-turnover ROD, related to secondary hyperparathyroidism; low-turnover ROD and mixed ROD.

Serum levels of intact parathyroid hormone (iPTH), osteocalcin (OC), procolagen-I-propeptide (PIPC) and dioxypiridinoline (DYP) were measured in 20 patients on hemodialysis (HD) and 20 patients on continuous ambulatory peritoneal dialysis (CAPD) to assess the prevalence of ROD type in the HD and CAPD groups.

We found lower mean levels of all bone markers in CAPD patients, (iPTH: 219+/-235 vs. 428+/-285 pg/ml; p<0.01; OC 10.2+/-7.5 vs. 21.3+/-7.2 ng/ml; p<0.01; PIPC 111+/-57.3 vs. 218+/-62.4 ng/ml; p<0.01; DYP 7.3+/-6.4 vs. 55.2+/-23.3nm/l; p<0.001; AP 164+/-66 vs. 325+/-188 U/l; p<0.01) and lower than normal in 11 of them and higher than normal PTH, AP and some of the other serum markers (PICP; DYP) in 14 HD patients.

The lower levels of the investigated serum bone markers in CAPD patients suggest that low-turnover ROD prevails in these patients than in HD pts.