Dynamics of bone turnover in children with GH deficiency treated with GH until final height

Objective: To examine the dynamics of bone turnover in children with growth hormone deficiency (GHD) during long-term treatment. Design: We longitudinally measured growth velocity and serum concentrations of osteocalcin (OC), carboxyterminal propeptide of type I procollagen (PICP), and cross-linked carboxyterminal telopeptide of type I collagen (ICTP) in 24 patients with GHD during long-term GH treatment until final height (age: 7.7 +/- 0.7 and 16.9 +/- 0.5 years at baseline and at final height respectively). Results: At baseline, OC, PICP, and ICTP levels were significantly (P < 0.0001) reduced in comparison with prepubertal bone age-matched controls (10.2 +/- 2.3 mu g/l and 22.5 +/- 7.6 mu g/l; 187.8 +/- 26.2 mu g/l and 328.4 +/- 74.3 mu g/l; 7.7 +/- 2.0 mu g/l and 14.2 +/- 1.3 mu g/l respectively). During the first year of treatment mean levels of the bone markers increased significantly (P < 0.0001) with a peak at 12 months. After the first year of treatment, OC and PICP levels progressively declined, whereas ICTP levels remained stable until the final height; in any case, bone marker levels remained significantly higher (P < 0.03-P < 0.0001) than baseline. The change in bone marker levels at 6 and 12 months of treatment with respect to the baseline values was not related to growth rate during long-term treatment or final height. Conclusions: The results show that children with GHD have reduced bone turnover at baseline and that long-term GH treatment is associated with a stimulation of bone turnover. OC, PICP, and ICTP do not predict growth rate during long-term treatment or final height in children with GHD.