Objective: To evaluate the incidence and identify predictive factor of hypothyroidism after hemithyroidectomy in non-Hashimoto’s thyroiditis.

Materials and Methods: A retrospective study was conducted between May 2013 and May 2017 in 66 patients that underwent hemithyroidectomy for benign non-Hashimoto’s thyroiditis thyroid diseases. SPSS (v20.0) was used to analyze the data. A p-value lower than 0.05 was considered statistically significant.

Results: There were 66 patients, with a predominance of women (87.9%), and the mean age was 48.7 years. The majority of histological reports were adenomatous nodule or nodular goiter in 63 patients (95.5%). The three remaining patients had adenoma. Seven patients (10.6%) developed hypothyroidism. Levothyroxine was prescribed in three patients who developed overt hypothyroidism and four patients who complained about hormone decreasing symptoms. The mean follow-up period was 12 weeks. In univariate analysis, preoperative thyroid-stimulating hormone (TSH) level of 1.20 mIU/L or more (OR 10.1, 95% CI 1.14 to 89.45) was the predictor for postoperative hypothyroidism. Other factors included sex, age, preoperative free T4 level, size and weight of surgical specimen, cystic degeneration on histology, and pathological diagnosis were not established as predictive factors.

Conclusion: In benign non-Hashimoto’s thyroiditis thyroid disease, patients who had preoperative TSH level of 1.20 mIU/L or more were considered as high risk for post-hemithyroidectomy thyroid hormone depletion. Clinical symptoms associated hypothyroidism should be observed carefully in patients with this TSH level cut point. In addition, postoperative monitoring for hypothyroidism should be started at 12 weeks.

Keywords: Hypothyroidism, Hemithyroidectomy, Thyroidectomy, Lymphocytic thyroiditis, Hashimoto’s thyroiditis