Is Partial or Total Thyroidectomy Associated with Risk of Long-Term Osteoporosis: A Nationwide Population-Based Study

Background: Whether thyroidectomy contributes to osteoporosis (OP) and osteoporotic fracture (OF) is a subject of debate. This study aimed to determine the effect of thyroidectomy on the risk of OP and OF. Methods: This retrospective cohort study is based on patient data between January 2000 to December 2005 from the National Health Insurance Research Database. Patients who underwent thyroidectomy were enrolled in the thyroidectomy cohort, and the control cohort was selected by propensity score matching at a ratio of 1:4. Incident OP and OF cases were identified until the end of 2013. The thyroidectomy cohort to control cohort adjusted hazard ratio (aHR) for OP/OF was assessed through multivariable Cox proportional hazard regression analysis. Results: Totals of 1426 and 5704 patients were included in the thyroidectomy and control cohorts, respectively. The incidence density of OP was higher in the thyroidectomy cohort (7.91/1000 person-years) than in the control cohort (5.98/1000 person-years), with an aHR of 1.43 (95% CI 1.16–1.77, p < 0.05). Younger patients, women, and patients with comorbidities were at a higher risk. The risks of postoperative OP/OF were significantly increased in patients who received thyroxine treatment for more than 1 year, both in the partial thyroidectomy group and in the total and subtotal thyroidectomy group (aHR: 2.47, 95% CI: 1.42–2.31 vs. aHR: 1.84, 95% CI: 1.22–2.76). Conclusion: Thyroidectomy significantly increased the long-term risk of OP. Younger patients, women, patients with comorbidities, and patients receiving chronic thyroxin treatment should be monitored for changes in postoperative bone density.