Thyrotropin Levels Within the Lower Normal Range Are Associated With an Increased Risk of Hip Fractures in Euthyroid Women, But Not Men, Over the Age of 65 Years

Context: The contemporary literature on the relationship between serum TSH levels and osteoporotic fractures in euthyroid individuals is limited by conflicting results and analyses conducted on a small number of fractures. Objective: Our objective was to examine the association between the normal range of variation of TSH and the incidence of hip fractures in male and female euthyroid patients aged 65 years or older. Design and Setting: We performed a population-based historical prospective cohort study within the Clalit Health Services population. Participants: Clalit Health Services members aged >= 65 years with at least 1 TSH measurement during the year 2004. We excluded patients with preexisting hip fracture, thyroid disease, malignancy, or chronic kidney disease. Outcome Measures: The primary outcome was hip fracture, and the secondary outcome was any other osteoporotic fracture. Statistical Analysis: Adjusted odds ratios comparing episodes of each outcome across 3 TSH groups (low, 0.35-1.6 mIU/L; intermediate, 1.7-2.9 mIU/L; high, 3-4.2 mIU/L) were generated using logistic regression models. Results: The 14 325 included participants suffered from 514 hip fractures (mean follow-up, 102 +/- 3 months). Women, but not men, in the lowest TSH group had a higher incidence of hip fractures (odds ratio = 1.28, 95% confidence interval = 1.03-1.59, P = .029) when compared with the intermediate group, after multivariate adjustment for age, comorbidities, and use of drugs affecting bone metabolism. There was no difference in hip fracture incidence between intermediate- and high-TSH groups. No association was found between TSH levels and other osteoporotic fractures. Conclusions: TSH levels within the lower normal range are associated with an increased risk of hip fractures in euthyroid women, but not men, aged 65 years and more.