Two or three weeks of thyroid hormone withdrawal before initial ¹³¹I therapy for patients with differentiated thyroid...

To evaluate the effects of different thyroid hormone withdrawal (THW) duration before initial ¹³¹I therapy on the level of thyrotropin (TSH), biochemical parameters and prognosis in patients with differentiated thyroid cancer (DTC).

DTC patients who underwent total thyroidectomy between January 2016 and August 2018 before initial ¹³¹I therapy were included. Patients undergoing two-week and three-week THW were categorized into groups A and B. Factors influencing TSH ≥ 30 mIU/L, changes in biochemical parameters before surgery and after THW, and prognosis after ¹³¹I therapy were evaluated and compared.

Totally, 95.3% (303/318) of patients had TSH ≥ 30 mIU/L after THW. The rate of TSH ≥ 30 mIU/L in groups A and B was 93.8% (152/162) and 96.8% (151/156), respectively (P = 0.212). Age was the only factor influencing TSH ≥ 30 mIU/L (hazard ratio [HR] 0.937, 95% confidence interval [CI] 0.882-0.997, P = 0.038). Changes of creatinine, alanine aminotransferase, aspartate aminotransferase, cholesterol, high-density lipoprotein and low-density lipoprotein before and after THW were higher in group B than in group A (all P < 0.05). After a median follow-up of 55 months, the rate of disease persistence/recurrence in groups A and B was 6.2% (7/113) and 2.3% (3/128), respectively (P = 0.241). Stimulated thyroglobulin before ¹³¹I therapy was the only predictor for disease persistence/recurrence (HR 1.028, 95%CI 1.012-1.043).

Two-week THW was an effective strategy to achieve TSH ≥ 30 mIU/L before ¹³¹I therapy in patients younger than 50 years old and had less effect on changes in biochemical parameters, while there was no difference in the prognosis between two-week and three-week THW.