The relationship between thyroid function and bone mineral density in euthyroid healthy subjects in Taiwan

It has been reported that low normal circulating thyrotropin (TSH) levels correlate with lower bone mineral density (BMD) in the Korean postmenopausal female. The goal of this study is to evaluate this relationship in different sex and age groups in a Chinese population. Materials and methods. A total of 2,957 subjects in Taiwan, 1,343 males and 1,614 females, aged from 45 to 64 years, were enrolled in this study. They were divided into four groups: group 1 was males aged between 45 and 50 years (young male, YM); group 2 was females aged between 45 and 50 years (young female, YF); group 3 was males older than 50 years (old male, OM); and group 4 was females older than 50 years (old female, OF). Plasma total thyroxine (T4) and TSH were measured. BMD was quantified at the wrist using dual energy X-ray absorptiometry. Results. YM had the highest BMD whereas OF had the lowest BMD. Among the four groups, no significant correlation between TSH level and BMD was found in the four groups, but a significant negative correlation existed between T4 and BMD in OF (r = -0.089, p = 0.005) and YM (r = -0.109, p = 0.018). Conclusion. Our study did not find significant correlations between TSH and BMD in both men and women with normal thyroid function in Taiwan. Weak negative correlations existed between T4 and BMD in postmenopausal women and young men. Further studies with measurement of FT4 and TSH and with a longitudinal design may shed light on this population difference.