Analysis of the strategy of LT4 prescribing and TSH monitoring for thyroid carcinoma after lobectomy

BACKGROUND: Thyrotropin (TSH) suppression is a critical step in the management of differentiated thyroid carcinoma (DTC). The objectives of this study were to evaluate changes in TSH levels and a strategy of initial levothyroxine (LT4) supplementation for TSH suppression in low-risk differentiated thyroid carcinoma (lr-DTC) patients after lobectomy. METHODS: One hundred and ten patients with lr-DTC who received lobectomy were enrolled. Each of the patients was given 50 µg LT4 immediately after lobectomy and were retrospectively analyzed to evaluate the initial dose of LT4 suppression during the first year of follow-up. Risk factors influencing the TSH trend were also evaluated. RESULTS: Median TSH levels decreased significantly after lobectomy and the initiation of LT4 suppression and were stable from 3 to 12 months. Three months after lobectomy, 44.9% of patients fell into the newly recommended first TSH goal (0.35 to 2.0 mIU/L). Insufficient suppression (≥2.0 mIU/L) and oversuppression (<0.35 mIU/L) was observed in 9.4% and 45.8% of the patients, respectively. Preoperative TSH ≥2.0 mIU/L and the coexistence of Hashimoto thyroiditis (HT) were risk factors influencing the TSH trend. CONCLUSIONS: The monitoring of TSH could start from 3 months after lobectomy. An initial dose (50 µg) of LT4 could be adequate for initial suppression therapy in most patients. However, individual adjustment of the first dose may be necessary based on preoperative TSH concentration and the presence of HT.