A 30-year-old woman is planned for radioactive iodine (RAI) ablation 6 weeks after total thyroidectomy for low-risk differentiated thyroid cancer. She is euthyroid on levothyroxine withdrawal. Which preparation is required before RAI administration to maximise thyroid remnant uptake?

• A Continue levothyroxine and administer recombinant human TSH (rhTSH) injections
• B Intravenous iodine loading to saturate the thyroid remnant
• C Administer high-dose corticosteroids to enhance iodine uptake
• D Withhold levothyroxine for 3-4 weeks to achieve TSH >30 mIU/L, with a low-iodine diet for 2 weeks ✓

Explanation

For RAI remnant ablation, the patient must have elevated TSH (>30 mIU/L) to stimulate TSH receptor-mediated iodine uptake by thyroid tissue. This is achieved by levothyroxine withdrawal for 3-4 weeks (or triiodothyronine withdrawal for 2 weeks). A low-iodine diet for 2 weeks further enhances uptake. rhTSH is an alternative where levothyroxine is continued and rhTSH is given intramuscularly.

Reference: Williams Textbook of Endocrinology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.