Ahn D, et al. - In patients with papillary thyroid carcinoma (PTC), researchers assessed the oncological impact of hypothyroidism and levothyroxine (LT) supplementation after hemithyroidectomy. Four hundred one patients who had hemithyroidectomy for classic PTC and who were postoperatively followed-up with ≥ 3 thyroid function measurements for ≥ 24 months were retrospectively analyzed. Findings revealed that 268/401 patients developed hypothyroidism and 19/401 patients showed recurrence during 77.4 months of follow-up. The rate of recurrence did not vary between the euthyroidism and hypothyroidism development groups. Although mean postoperative thyroid-stimulating hormone (TSH) levels were not different between the two groups, recurrence rates were significantly lower in the LT group than in the no-LT group. According to univariate and multivariate analysis, tumors sized > 1 cm and lack of LT supplementation were significantly linked to recurrence. The development of postoperative hypothyroidism was not a risk factor for PTC recurrence after hemithyroidectomy. LT supplementation, however, reduced the risk of recurrence without suppressing TSH.