Thyroid-stimulating hormone decreases the risk of osteoporosis by regulating osteoblast proliferation and differentiation

Background: As the incidence of secretory osteoporosis increases, bone loss and osteoporosis and their relationships with thyroid-stimulating hormone (TSH) have received increased attention. In this study, the role of TSH in bone metabolism and the underlying possible mechanisms were investigated. Methods We analyzed serum triiodothyronine (FT3), tetraiodothyronine (FT4), TSH and bone mineral density (BMD) levels of 114 men with normal thyroid function. In addition, osteoblasts from rat calvarial samples were treated with different doses of TSH for different times at each time point. The related gene and protein expression levels were investigated. Results Comparing the BMD between the high-level and low-level serum TSH group showed that TSH serum concentrations were positively correlated with BMD. TSH at concentrations of 10 mU/mL and 100 mU/mL significantly increased the mRNA levels of ALP, COI1 and Runx2 compared with those of the control (P < 0.05, P < 0.01). BMP2 activity was enhanced both with increased TSH concentration and with increased time. The protein levels of Runx2 and osterix were increased in a dose-dependent manner. Conclusions The circulating concentrations of TSH and BMD were positively correlated with normal thyroid function in males. TSH promoted osteoblast proliferation and differentiation in rat primary osteoblasts.