Hypothyroidism After Hemithyroidectomy: Incidence, Prevalence, and Risk Factors

Background Hemithyroidectomy preserves contralateral lobe function but may lead to postoperative hypothyroidism. We evaluated its incidence and predictors in a large population-based cohort. Case Report We conducted a retrospective cohort study of 7177 adults undergoing hemithyroidectomy between 2002 and 2019 within an integrated health care system. Thyroid function was assessed preoperatively and longitudinally postoperatively. Logistic regression identified risk factors. Discussion Postoperative hypothyroidism developed in 52.6% of patients, predominantly subclinical. Elevated preoperative thyroid-stimulating hormone was associated with risk in a dose-dependent manner. Most cases were diagnosed within 32 months. Older age showed a protective association in univariate analysis. Conclusion Hypothyroidism following hemithyroidectomy is common and often delayed. Preoperative thyroid-stimulating hormone is the strongest predictor. Structured long-term monitoring is warranted.