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

• Main Authors: Subramanian Kannan, Shriraam Mahadevan, Dhalapathy Sadacharan, K Thirumurthi
• Format: Article
• Language: English
• Published: Wolters Kluwer Medknow Publications 2019-01-01
• Series: Indian Journal of Endocrinology and Metabolism
• Subjects: Whole-body iodine scan; thyroid cancer; TSH withdrawal scan
• Online Access: http://www.ijem.in/article.asp?issn=2230-8210;year=2019;volume=23;issue=4;spage=452;epage=455;aulast=Kannan

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 Thyroid hormone is withdrawn 3–4 weeks prior radioiodine therapy (RAIT) to allow the serum-TSH concentration to rise to above 25–30 mU/L. Aims: We studied the time taken for TSH to rise in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.