Association of serum thyroid-stimulating hormone and bone mineral density in Chinese adults with normal thyroid function

Purpose This study aims to investigate the association of serum TSH with BMD in Chinese adults with normal thyroid function. Methods These participants were divided into tertiles based on serum TSH levels. Linear regression model and multinomial logistic regression models were used to analyze the associations of continuous BMD and categorical BMD with serum TSH, respectively. Results In women younger than 60 years, BMD decreased with the increase of TSH at normal level, while in women older than 60 years, BMD increased with the increase of TSH at normal level; besides, the BMD of women younger than 60 years old was significantly higher than that of women over 60 years old (156.05 +/- 39.34 mg/cm3 vs. 86.95 +/- 29.51 mg/cm3, P < 0.001). Linear regression results showed negative associations of BMD and normal TSH level in women with age younger than 60 years (beta=-4.34, P < 0.001), but this inverse trend was observed in women over 60 years old (beta = 2.04, P = 0.041). Both in men younger than 60 years and over 60 years old, BMD decreased with the increase of TSH at normal levels; besides, the BMD of men younger than 60 years was significantly higher than those over 60 years old (143.08 +/- 32.76 mg/cm3 vs. 108.13 +/- 31.99 mg/cm3, P < 0.001). Conclusions The results demonstrated an opposite trend in BMD at normal TSH levels in younger and elder females, that is, in females younger than 60 years, BMD decreased with the increase of TSH, which indicated that TSH might play a different role in younger and elder females. However, this trend was not significant in males.