Influence of Thyroid Function on Serum Bone Gla Protein

Abstract

The serum BGP level was assayed in patients with hyperthyroidism (untreated and remittent cases) and hypothyroidism. The mean serum BGP concentration was 9.7± 0.90 ngml in 30 patients with untreated hyperthyroidism which was significantly higher than the 2.7± 0.38 ng/ml in 15 remittent patients and 1.3± 0.31 ng/ml in 13 patients with hypothyroidism (p<0.001, p<0.001). Serum BGP had a significant positive correlation with the concentrations of free triiodothyronine and alkaline phosphatase in the serum, while it had a significant negative correlation with serum PTH. In the patients with hypothyroidism, serum BGP increased significantly in parallel with increases in serum free triiodothyronine with thyroxine therapy. In the patients with hyperthyroidism, serum free triiodothyronine decreased significantly after the first month of methimazole treatment, and fluctuated within then ormalrange after two months. Serum alkaline phosphatase and BGP did not show significant changes during the first six months of treatment, although they were eventually reduced significantly at the end of one year.
These results suggest that thyroid hormone directly stimulates the synthesis and secretion of BGP in existent osteoblasts and also acts on the bone remodeling cycle, therapy accelerating the rate of bone formation; the latter action may occur over a long period.