Biochemical markers of bone remodeling correlate negatively with circulating TSH in postmenopausal women

To evaluate the interrelations between circulating TSH and bone metabolism in postmenopausal women.

In a total of 60 postmenopausal women serum level of several hormones (thyrotropin [TSH], free thyroxine [FT4], dehydroepiandrosterone sulfate [DHEAS], parathyroid hormone [PTH]), bone turnover markers (carboxyterminal propeptide of type I procollagen [PICP] and cross-linked telopeptide of type I collagen [ICTP]) as well as of other compounds such as IGF-I, sex hormone binding globulin (SHBG), 25-OH vitamin D3 (25-OHD3) and urinary free deoxypyridinoline (Dpd (2h)) concentrations were estimated. Bone mineral density (BMD) at the spine and BMD at the hip were measured by DXA method.

Sperman's correlation showed negative association between serum TSH and urinary Dpd (p<0.021) and borderline, but not significant negative correlation between TSH and ICTP (p<0.064). However, no correlation was found between TSH and serum PICP. In addition, no correlation was found between FT4 and such parameters of bone remodeling. Expected positive association between serum IGF-I and DHEAS (p<0.000), between body mass index (BMI) and serum DHEAS (p<0.015) and negative correlation between BMI and SHGB (p<0.002) were confirmed. Moreover, negative correlation was found between bone mineral density at the hip and serum SHBG levels (p<0.000) and positive correlation between BMD at the hip and DHEAS level (p<0.003). Additionally, 36.5 % variability in TSH levels and 30.5% variability in FT4 in our cohort shared with the factor TSH and bone remodeling (factor analysis).

This cross-sectional study suggested negative association between serum TSH and markers of bone resorption in postmenopausal women. It also confirmed the well known mutual interrelations between BMD at the hip and a number of hormonal indices. Although our results did not provide any evidence on the effect of serum TSH and/or SHBG and DHEAS on bone metabolism, they showed some predictive value of these parameters to bone health.