Is 3-4 Weeks Required for TSH to Rise Post Thyroidectomy? A prospective Study and Discussion of its Implications on...

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 Thyroid hormone is withdrawn 3-4 weeks prior radioiodine therapy (RAIT) to allow the serum-TSH concentration to rise to above 25-30 mU/L.

We studied the time taken for TSH to rise in 40 patients after total thyroidectomy operated for DTC.

Prospective observational study.

40 patients with proven differentiated thyroid cancer attending a tertiary care center were studied.

Data was analyzed by using SPPSS software for windows (version 15, SPSS Inc., Chicago, USA).

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.

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.