Correlation of thyroid function and sensitivity to thyroid hormone with spinal bone mineral content, bone mineral density, and osteoporotic vertebral fracture: A cross-sectional study based on NHANES.

Previous studies have demonstrated that thyroid hormone plays an important role in normal bone development, bone metabolism, and establishment of peak bone mass. However, the correlation of thyroid status with bone mineral content (BMC), bone mineral density (BMD), and osteoporotic vertebral fracture (OVF) is rarely discussed. The current study probes into the potential association between thyroid status and spinal BMC, BMD, and OVF from a novel perspective of thyroid function (TF) and sensitivity to thyroid hormone based on the National Health and Nutrition Examination Survey database. A total of 1844 participants were included in this study. The association of thyroid status with outcome variables, like spinal BMC, BMD, and OVF, was analyzed using thyroid function indices and sensitivity to thyroid hormone indices as influence factors. The correlation of them were assessed using univariate and multivariable weighted linear regression, weighted logistic regression models, restricted cubic spline model, and subgroup analyses. The results of this study showed that the association of free triiodothyronine (FT3)/free thyroxine (FT4) with BMC remained negatively associated after adjustment for all covariates. Higher thyroid peroxidase antibody (TPOAb) was significantly associated with an increased risk of developing OVF in both unadjusted and adjusted models. In addition, the results of the restricted cubic spline model were consistent with the weighted multivariate regression analysis after adjustment. The results of this cross-sectional study showed that higher FT3/FT4 and TPOAb were associated with decreased spinal BMC and the increased risk of OVF, indicating a complex link between thyroid status and bone health. Therefore, patients with hyperthyroidism, hypothyroidism, autoimmune thyroid disease, or abnormal peripheral thyroid sensitivity, especially who with elevated TPOAb or FT3/FT4, should focus on the prevention of vertebral osteopenia, osteoporosis, and OVF.