To assess whether the patient preparation procedure for 131I scintigraphy could be streamlined, we evaluated the time course of thyroid-stimulating hormone (TSH) elevation after total thyroidectomy or after discontinuation of thyroxine (T4) in patients with thyroid cancer. Methods: The clinical records of 284 patients with well-differentiated thyroid cancer were reviewed. All patients had undergone total thyroidectomy. Two groups of patients were evaluated. The immediate postoperative group consisted of 176 patients who were not given thyroid hormone replacement after surgery because of planned postoperative 131I therapy. The surveillance group consisted of 108 patients in whom T4 replacement was stopped (without triiodothyronine [T3] replacement) in preparation for surveillance whole-body 131I scintigraphy. We recorded the first TSH measurement and number of days after surgery or without thyroid hormone for each patient. Results: In the immediate postoperative group, TSH levels obtained 6-65 d (median, 17 d) after surgery ranged from 18.2 to 194.8 μIU/mL (median, 46.6 μIU/mL). The TSH values exceeded 30 μIU/mL in 89% of patients evaluated at 1-2 wk, in 88% of those evaluated at 2-3 wk, and in 90% of those evaluated after 3 wk. In patients discontinuing T4 (without T3 replacement), TSH levels obtained from 6 to 35 d (median, 20 d) later ranged from 23.4 to 214.5 μIU/mL (median, 61.1 μIU/mL). The TSH levels exceeded 30 μIU/mL in 100% of patients evaluated at 1-2 wk, in 89% of those evaluated at 2-3 wk, and in 96% of those evaluated after 3 wk. Conclusion: In most patients with thyroid cancer being prepared for 131I imaging or therapy, a TSH level exceeding 30 μIU/mL can be achieved by withdrawal of thyroid hormone therapy for 1-3 wk.
|Number of pages||4|
|Journal||Journal of Nuclear Medicine|
|State||Published - Apr 1 2004|
- Thyroid cancer
- Thyroid-stimulating hormone