RESUMO
PURPOSE: This study evaluated the risk factors for hypothyroidism after lobectomy for low risk papillary thyroid carcinoma according to existence of thyroiditis, especially on preoperative thyroid stimulating hormone (TSH) level and remnant thyroid volume. METHODS: The clinical records of 169 patients who underwent thyroid lobectomy due to papillary thyroid carcinoma were reviewed. We maintain the TSH level between 0.10~0.50 mU/L with thyroid hormone until 6 to 12 months after lobectomy. Then we stopped medication and check TSH level at intervals of 2~6 months. The patients were divided into 2 groups; hypothyroid (n=63) and euthyroid (n=106) state after lobectomy. Euthyroid state was defined as an TSH level between 0.50~5.0 mU/L, hypothyroid state as an elevated TSH level above 10 mU/L and need thyroid hormone. RESULTS: Factor for age, sex, type of operation, result of biopsy were not significant to postoperative hypothyroidism. Presence of thyroid autoantibody was significantly different (P0.05). When patient didn't have thyroiditis, there was high possibility of postoperative hypothyroidism when preoperative TSH is in high normal level and remnant thyroid volume ratio is below 50% (P<0.01). CONCLUSION: One can check the presence of thyroiditis with thyroid autoantibody and can predict the possibility of postoperative hypothyroidism after lobectomy in patients with low risk papillary thyroid carcinoma with preoperative TSH level and remnant thyroid volume.