Deng T, Zhang W, Zhang Y, et al. - This study was undertaken to explore the role of thyroid-stimulating hormone (TSH) in bone metabolism and its possible underlying mechanisms by examining the serum levels of free triiodothyronine, free thyroxine, and TSH and the bone mineral density (BMD) levels of 114 men with normal thyroid function. Researchers further assessed the related gene and protein expression levels. The results exhibited that in males, circulating concentrations of TSH and BMD were positively associated with normal thyroid function. In rat primary osteoblasts, TSH promoted osteoblast proliferation and differentiation. TSH serum concentration was positively associated with BMD after comparing the BMD of the high-level vs low-level serum TSH groups. TSH at concentrations of 10 mU/mL and 100 mU/mL significantly raised the mRNA levels of ALP, COI1 and Runx2 vs the control. With both increased TSH concentration and increased time, bone morphogenetic protein (BMP)2 activity was enhanced.