Hyperthyroidism and bone mineral density: Dissecting the causal association with Mendelian randomization analysis.

Area of Science:

• Endocrinology
• Genetics
• Bone Metabolism

Background:

• Untreated hyperthyroidism accelerates bone turnover, reduces bone mineral density (BMD), and increases fracture risk.
• While treatment may improve skeletal health, guidelines for post-treatment BMD assessment are lacking.

Purpose of the Study:

• To investigate the causal relationship between genetic predisposition to hyperthyroid states and bone mineral density (BMD) and fracture risk.
• To inform clinical practice regarding osteoporosis screening in patients with a history of hyperthyroidism.

Main Methods:

• Utilized Mendelian randomization (MR) analysis on UK Biobank data (n=473,818).
• Assessed heel quantitative ultrasound BMD and self-reported fractures.
• Employed beta-weighted genetic risk scores for Graves' disease, hyperthyroidism, and autoimmune thyroiditis, with sensitivity analyses using MR-Egger and inverse-variance weighted methods.

Main Results:

• No significant association was found between genetic risk for Graves' disease, autoimmune thyroiditis, or hyperthyroidism and heel ultrasound BMD.
• Sensitivity analyses and replication using GEFOS data confirmed these null findings.
• Genetic predisposition to these hyperthyroid conditions was not linked to an increased risk of fractures.

Conclusions:

• Genetic predisposition to Graves' disease and hyperthyroidism does not confer an increased risk of low BMD or fractures in the Caucasian population.
• Findings do not support the routine screening for osteoporosis following treatment for hyperthyroid conditions.