Plasma levels of carboxy terminal propeptide of type I procollagen and pyridinoline cross-linked telopeptide of type I collagen in healthy school children

The aim of this study was to reveal the relationship of the plasma levels of the carboxy terminal propeptide of type I procollagen (PICP) and the pyridinoline cross-linked carboxyterminal telopeptide domains of type I collagen (ICTP) to age and height velocity (HV), and to compare PICP and ICTP levels in those who have not reached their final height with those who have. PICP and ICTP levels were measured by RIA in 271 healthy children (161M, 110F) aged from 10 to 15 y. The HV was calculated from their health check-up cards. The subjects were divided into two groups in this study: the final height (FH) group whose HV was < 1.0 cm/y, and the non-final height (NFH) group whose HV in the last year was ≥ 1.0 cm/y. PICP and ICTP levels almost paralleled the values of age-related changes of HV. Furthermore PICP and ICTP levels significantly correlated with HV. PICP and ICTP levels of the FH group were higher than those of adults previously reported. The values will be useful as reference for healthy children and growth disorder. Before reaching final height, PICP and ICTP can be useful makers of not only bone turnover but also of linear growth. Bone turnover rate is still increasingly active just after linear growth has been completed, and then it become similar to the levels of adults.