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

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

Patients And Methods: 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.

Results: 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).

Conclusion: 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.