A territory-wide assessment of the incidence of persistent hypoparathyroidism after elective thyroid surgery and its impact on new fracture risk over time.

Background: Although persistent (≥6 months) postoperative hypoparathyroidism is often believed to be rare after elective total thyroidectomy, we hypothesized a higher incidence in the community and that patients with persistent postoperative hypoparathyroidism may have a higher fracture risk. A population-based analysis was performed using an electronic health database to address these issues.

Methods: All elective total thyroidectomies performed in 14 major hospitals across the territory over 20 years were analyzed. Persistent postoperative hypoparathyroidism was defined by the requirement of oral calcium and vitamin D shortly postoperatively and continued for ≥6 months. Those with albumin-corrected calcium <1.90 mmol/L on ≥1 occasion beyond 1 year postoperation were considered suboptimally controlled. Patients were followed until an index fracture, death, or the time of analysis, whichever was earlier. Multivariable Cox regression analysis was used to identify clinical predictors for fractures.

Results: Among 4,123 eligible patients, 460 patients (11.2%) had persistent postoperative hypoparathyroidism. Over a median of 10.3 years, 126 patients suffered from a new fracture (2.77 per 1,000 person-years). There was no difference in fracture events between patients with and without persistent postoperative hypoparathyroidism (P = .761). Subgroup analyses according to the adequacy of persistent postoperative hypoparathyroidism control did not reveal significant differences in fracture events. Age, female, history of fall, and diabetes independently predicted post-thyroidectomy fractures.

Conclusion: Persistent postoperative hypoparathyroidism appeared to be a more common complication in the community after elective total thyroidectomy than previously thought. We did not observe a significant difference in fracture risk between patients with and without persistent postoperative hypoparathyroidism. The impact of persistent postoperative hypoparathyroidism control on fracture risk remained to be determined.