Association between subclinical thyroid dysfunction and change in bone mineral density in prospective cohorts

Area of Science:

• Endocrinology
• Gerontology
• Bone Metabolism

Background:

• Subclinical hyperthyroidism (SHyper) is associated with higher fracture risk, but the underlying mechanisms are not fully understood.
• Investigating the relationship between thyroid dysfunction and bone density is crucial for understanding fracture etiology in aging populations.

Purpose of the Study:

• To examine the association between subclinical thyroid dysfunction and bone loss using individual participant data from prospective cohorts.
• To quantify the impact of SHyper and subclinical hypothyroidism (SHypo) on bone mineral density (BMD) changes over time.

Main Methods:

• Systematic literature search of MEDLINE/EMBASE (1946-2016) to identify relevant prospective cohorts.
• Analysis of data from 5458 individuals, classifying thyroid status by TSH levels (euthyroidism, SHyper, SHypo).
• Multivariable regression modeling to assess annualized %BMD change at the femoral neck, total hip, and lumbar spine.

Main Results:

• Subclinical hyperthyroidism (SHyper) was associated with increased annual bone loss at the femoral neck (%ΔBMD = -0.18) compared to euthyroidism.
• Participants with TSH < 0.10 mIU/L exhibited significantly greater bone loss in the femoral neck and total hip regions.
• Subclinical hypothyroidism (SHypo) was not significantly associated with bone loss at any measured skeletal site.

Conclusions:

• Subclinical hyperthyroidism is linked to accelerated bone loss, particularly at the femoral neck, in adults.
• This increased bone loss may be a key mechanism contributing to the elevated fracture risk observed in individuals with SHyper.
• Subclinical hypothyroidism does not appear to influence bone loss in this cohort.