Predictors of thyroxine replacement following hemithyroidectomy in a south east Asian cohort.

Background Thyroxine replacement following a hemithyroidectomy is not commonly discussed during consent for the procedure as the risk of hypothyroidism is perceived to be low. Methods Retrospective review of 901 patients who underwent hemithyroidectomy at a tertiary referral institution during the period January 2000 to December 2015. The main outcome studied was the overall incidence of hypothyroidism and the associated risk factors. Results Hypothyroidism developed in 123 (13%) patients and 94 patients (10%) required hormone supplementation over a mean follow up of 21 months (range 1-168 months). Preoperative TSH of more than 2.5 was seen in 38 of 123 (31%) of patients. Presence of diffuse thyroiditis was the only independent risk factor on multivariate analysis (P = 0.002) found to be associated with the development of hypothyroidism. Conclusion After thyroid lobectomy, approximately one in 10 patients requiring thyroid hormone treatment for hypothyroidism. Presence of diffuse thyroiditis is a significant risk factor for hypothyroidism.