The association between thyroid function and bone mass density

The relation between thyroid hormone and bone microarchitecture at tibial level is not clear. This study aimed to assessthe correlation between thyrotropin and free thyroxine in a large cohort of participants from the SardiNIA study.

Peripheral quantitative computed tomography (pQCT) was assessed on 4413 participants (55.0% female). Parameters of pQCT were analyzed separately as exposure variables, while thyroid hormones (thyrotropin and free thyroxine) were treated as independent variables in multivariate regression models.

After adjusting for confounders, free thyroxine was negatively associated with both total bone density at 4% level (coefficient - 7.26, standard error 2.78, p = 0.009) and cortical bone density at 38% level (coefficient - 11.44, standard error 3.57, p = 0.001). FT4 had also a positive association with eccentricity index at 38% level (coefficient 0.017, standard error 0.01, p = 0.008). TSH showed a positive association with total and trabecular bone density at 4% level (respectively, coefficient 0.79, standard error 0.34, p = 0.021 and coefficient 0.83, standard error 0.31, p = 0.008).

Thyroid hormones are associated with a weaker bone geometry at tibia level. This finding may support the hypothesis that excess of thyroid hormones has deleterious effect on bone microarchitecture. Further studies are needed to determine whether targeted treatment could help mitigate bone loss in patients with thyroid disorders.