Clinical and biochemical predictors of postoperative thyroid hormone replacement requirement in long-term follow-up after thyroid lobectomy

This study aimed to identify the clinical, biochemical, and pathological factors that predict the necessity of thyroid hormone replacement therapy following thyroid lobectomy (LT) and to assess their influence on postoperative hormone replacement requirements. This retrospective cohort study included 367 patients who underwent thyroid LT, with or without isthmectomy between 2012 and 2024. The collected data included demographic information, preoperative and postoperative thyroid function test results, thyroid ultrasound and pathological findings. Patients were followed-up postoperatively for an average duration of 45 months. Among the 367 patients, 22.6% (n = 83) required postoperative thyroid hormone replacement. Multivariate analysis identified several predictors for this requirement: a thyroid-stimulating hormone (TSH) level exceeding 2.53 µIU/mL at 6 to 8 weeks post-surgery (odds ratio [OR]: 1.125; P = .03), the presence of lymphocytic infiltration on pathological examination (OR: 2.624; P = .003), residual thyroid lobe volume of ≤5.234 cubic centimeters (cc) (OR: 1.17; P = .001), thyroiditis detected via preoperative ultrasound (OR: 3.771; P = .001). Receiver operating characteristic analysis demonstrated that a postoperative TSH level > 2.53 µIU/mL exhibited a sensitivity of 78.95% and a specificity of 71.76% (area under the curve = 0.786, P < .001), whereas a remaining lobe volume of ≤5.234 cc showed a sensitivity of 61.45% and a specificity of 74.30% (area under the curve = 0.686, P < .001). Our study suggests that TSH levels exceeding 2.53 µIU/mL, thyroid lobe volume ≤5.234 cc, lymphocytic infiltration, thyroiditis detected on preoperative ultrasound were identified as risk factors for the need for thyroid hormone replacement following thyroid LT. Individualized preoperative assessment coupled with long-term follow-up may be useful in determining the necessity of hormone replacement therapy after LT.