Serum bone-Gla protein (BGP) and carboxyterminal cross-linked telopeptide of type I collagen (ICTP) levels in patients with primary hyperparathyroidism before and after surgery

The accurate biochemical evaluation of bone turnover is often prevented by the lack of specific and reliable markers of bone formation and especially of bone resorption. In this study, serum bone Gla-protein (BGP), marker of osteoblastic function, and serum carboxyterminal telopeptide of type I collagen (ICTP), index of bone resorption, were evaluated in 6 patients with primary hyperparathyroidism before, 10 days and 3 months after surgery. Mean baseline BGP (25.0±3.4 ng/ml) and ICTP (5.7±0.5 ng/ml) levels were significantly higher than in normal subjects. After parathyroidectomy, serum BGP and ICTP levels promptly decreased (at 10th day, BGP: 14.7±2.5 ng/ml; ICTP: 3.8±0.2 ng/ml), but remained significantly higher than those recorded in controls. Three months after surgery, serum ICTP levels normalized, while BGP levels remained significantly higher than in normals. In conclusion, our data show that serial determinations of serum BGP and of ICTP levels may be useful in monitoring the course of primary hyperparathyroidism.