Osteoporotic fracture risk in hypoparathyroidism following total thyroidectomy: a retrospective nationwide cohort study

Abstract Objective Hypoparathyroidism is an uncommon but significant complication of total thyroidectomy. As the incidence of thyroid cancer increases, the prevalence of hypoparathyroidism also increases. However, its effect on the risk of osteoporotic fractures remains poorly understood. We aimed to evaluate the risk of osteoporotic fractures in patients with postoperative hypoparathyroidism compared with that in a matched control group. Design This retrospective cohort study included 417 patients with hypoparathyroidism who had undergone total thyroidectomy for thyroid cancer (TC with hypoP) and 2085 matched controls from the Korean National Health Insurance Service-National Sample Cohort. Methods The osteoporotic fracture rates and associated risk factors were analyzed in comparison after propensity score matching. Results During a median follow-up period of 5.07 years (interquartile range 2.19-7.38), postoperative hypoparathyroidism was not associated with a significantly greater risk of osteoporotic fractures than that in the control group (hazard ratio [HR] 0.86, 95% confidence interval [CI], 0.59-1.24, P = .406). Age-specific analysis showed a trend toward higher fracture incidence in patients aged <50 years (HR 1.31, 95% CI, 0.53-3.22, P = .558) and a decreasing trend in those aged ≥50 years (HR 0.75, 95% CI, 0.51-1.12, P = .163), although the differences were not statistically significant. No significant differences in fracture risk were observed between the TC with and without hypoP groups across all fracture sites. The frequency of osteoporotic medication use was higher in the TC with hypoP group than in the control group, particularly among women aged <50 years. Conclusions Hypoparathyroidism after total thyroidectomy does not appear to increase the risk of osteoporotic fractures compared with that in matched controls in clinical practice.