Prediction of bone mass in renal hyperparathyroidism by newly developed bone metabolic markers: Evaluation of serum levels of carboxy-terminal pyridinoline cross-linked telopeptide of type I collagen and carboxy-terminal propeptide of type I procollagen

Serum levels of the carboxy-terminal pyridinoline cross-linked telopeptide of type I collagen (ICTP) and the carboxy-terminal propeptide of type I procollagen. (PICP) were measured in 95 patients with renal hyperparathyroidism who had undergone a total parathyroidectomy and autotransplantation of a small portion of the resected gland. The results were compared with the serum levels of other bone metabolic markers and bone mineral densities in the distal radius (R-BMD) and lumbar vertebrae (L-BMD), which were measured by dual energy x-ray absorptiometry and converted to the percentage of the mean value of sex- and age-matched healthy controls. The preoperative mean values of ICTP and PICP were 142.4 ng/ml and 187.8 ng/ml, respectively. Although the serum levels of PICP levels exceeded the normal range in 42.1% of the patients, those of ICTP exceeded it in all of them. The serum levels of ICTP correlated positively not only with those of tartrate-resistant acid phosphatase (TRACP), total alkaline phosphatase (ALP), and osteocalcin but also negatively with the values of %R-BMD and %L-BMD and seemed to manifest specifically the disturbance of bone metabolism; On the other hand the serum levels of PICP correlated with those bf ALP and TRACP but not with values of %BMDs. After surgery, the serum levels of ICTP decreased gradually, but those of PICP increased immediately up to peak values at 7 days and then decreased gradually after 14 days, reaching the normal range at 3 months. These changes in the bone metabolic markers seemed to reflect the change in bone metabolism that was converting from bone resorption to bone formation. The percent change in the PICP/ICTP ratio at 7 days correlated significantly with the percent change in R-BMD at 12 months, and it was suggested that postoperative bone gain might be predicted using a combination of postoperative changes in PICP and ICTP.