Is 3–4 weeks required for TSH to rise post thyroidectomy? A prospective study and discussion of its implications on patient care

Abstract

Context: In patients with differentiated thyroid cancer (DTC), for the purpose of radioiodine (131I) whole-body scan and treatment of remnant, or residual tumor, or metastatic disease, thyroid hormone withdrawal remains the standard approach for raising thyroid-stimulating hormone (TSH) levels to ensure adequate radioiodine uptake. Thyroid hormone is withdrawn 3–4 weeks prior radioiodine therapy (RAIT) to allow the serum-TSH concentration to rise to above 25–30 mU/L. Aims: We studied the time taken for TSH to rise in 40 patients after total thyroidectomy operated for DTC. Settings and Design: Prospective observational study. Methods and Materials: 40 patients with proven differentiated thyroid cancer attending a tertiary care center were studied. Statistical Analysis Used: Data was analyzed by using SPPSS software for windows (version 15, SPSS Inc., Chicago, USA). Results: After performing preoperative TSH in all patients excluding preoperative TSH elevation, it was planned to collect weekly postoperative samples till TSH ≥30. The mean (standard deviation, SD) age of the cohort was 40 (13) years with 35 females (88%) and their mean (SD) preoperative TSH was 3.6 (1.35) mIU/L. At the end of the first week postoperatively, the mean TSH of the cohort was 24.25 (6) with 8 patients (20%) achieving the cut-off of TSH ≥30 mIU/L and 30 patients (75%) achieving TSH level ≥20 mIU/L. At the end of the second week, the mean TSH was 53 (17) with all patients (100%) achieving a TSH level >30 mIU/ml. Conclusions: An iodine whole-body scan can be performed in 10–14 days after total thyroidectomy instead of the usual wait time of 4 weeks. This could improve patient QOL and avoid complications related to prolonged hypothyroidism.

Keywords

• Whole-body iodine scan
• thyroid cancer
• TSH withdrawal scan