Thyroid cancer (TC) is a prevalent endocrine malignancy with rising incidence attributed to advancements in diagnostic technology. Despite its generally favorable prognosis, postsurgical complications, including hypoparathyroidism, can cause long-term health challenges.

This study evaluated the risk of nonskeletal complications in patients with TC with hypoparathyroidism (TC with hypoP).

A retrospective cohort study was conducted using the National Health Insurance Service-National Sample Cohort (2002-2019), including patients with TC diagnosed between 2006 and 2019. Participants were categorized into TC with hypoP, TC without hypoparathyroidism (TC without hypoP), and matched controls. Propensity score matching and Cox proportional hazards models evaluated the incidence and risk of nonskeletal complications, including diabetes mellitus, dyslipidemia, cardiovascular and renal outcomes, and cataracts.

This study included 430 and 850 patients in the TC with hypoP and TC without hypoP groups, respectively, and their matched controls. The TC with hypoP group showed significantly higher risks of diabetes mellitus (HR 1.31, 95% CI 1.01-1.68), dyslipidemia (HR 1.29, 95% CI 1.06-1.57), urinary stones (HR 1.61, 95% CI 1.00-2.57), and cataracts (HR 1.50, 95% CI 1.15-1.95) than controls (all P < .05). Hypertension risk was higher in the TC with hypoP group vs the TC without hypoP group (HR 1.39, 95% CI 1.00-1.93, P = .048). Women had higher urinary stone risk, while cataract risk increased in patients aged over 50.

Patients with TC with hypoP are at an increased risk for specific nonskeletal complications, particularly older adults and women. These findings underscore the need for targeted monitoring and management strategies in this population. Further prospective studies are warranted to validate these associations and elucidate the underlying mechanisms.