Serum TSH values and risk of vertebral fractures in euthyroid post-menopausal women with low bone mineral density.

Introduction: There is evidence that variations of thyrotropin (TSH) even in its reference range may influence bone mineral density (BMD). In fact, low-normal TSH values have been associated with high prevalence of osteoporosis in post-menopausal women. However, data associating TSH and risk of fractures are scanty and limited to subjects with subclinical thyrotoxicosis.

Materials And Methods: In this observational study, we investigated the correlation between serum TSH and prevalence of radiological vertebral fractures in a cohort of 130 post-menopausal women with normal thyroid function.

Results: Osteoporosis was observed in 80 women (61.5%), whereas 49 women (37.7%) had osteopenia. Vertebral fractures were found in 49 women (37.7%), who were significantly older, with higher prevalence of osteoporosis and with lower serum TSH values as compared with women who did not fracture. Stratifying the patients according to serum TSH values, vertebral fractures were found to be significantly (p=0.004) more prevalent in first tertile (56.8%) of TSH values as compared with the second (23.3%) and third tertiles (32.6%). Multivariate logistic regression analysis demonstrated that low serum TSH maintained a significant correlation with vertebral fractures (odds ratio 2.8, C.I. 95% 1.20-6.79) even after correction for age, BMD, BMI and serum free-thyroxine values.

Discussion: Low-normal TSH values are associated with high prevalence of vertebral fractures in women with post-menopausal osteoporosis or osteopenia, independently of thyroid hormones, age and BMD.