Context: Recombinant human TSH (rhTSH) is used to evaluate thyroid carcinoma patients and off-label for 131I thyroid ablation and nontoxic goiter therapy. Objective: Our objective was to determine the optimal time for 131I administration after rhTSH. Participants: Twenty-five euthyroid nongoitrous volunteers participated in the study. Design: Baseline 24-h thyroid 123I uptake (RAIU) was measured, and then 0.1 mg rhTSH was administered. 123I was administered 24, 48, or 72 h after rhTSH, and a repeat 24-h RAIU was obtained. Setting: The study was conducted at an academic research center. Main Outcome Measures: Thyroid function tests, thyroid ultrasounds, and electrocardiograms were measured before rhTSH, then daily for 4 d, and finally 7 d after rhTSH. Results: Serum TSH concentrations 24 h after rhTSH increased from 1.7 ± 0.5 μU/ml (mean ± SD) to 13.3 ± 4. The 24-h RAIUs rose from 25 ± 5 to 47 ± 8% (88% increase) when the 123I was given at 24 h after rhTSH and from 29.8 ± 7 to 40.5 ± 13% (36% increase) when the 123I was given at 48 h and were unchanged when the 123I was given at 72 h. The post-rhTSH RAIU increase was greater at 24 than at 72 h (P < 0.005) and marginally greater than at 48 h (P < 0.057). Thyroid volumes significantly increased 48 h after rhTSH (10 ± 3.8 vs. 11.1 ± 3.7 ml; P < 0.009). Electrocardiograms were normal. Conclusions: Marked increases in RAIU occurred when 123I was given 24 h after rhTSH administration to euthyroid volunteers. Smaller increases were observed at 48 h and none at 72 h.
|Number of pages||5|
|Journal||Journal of Clinical Endocrinology and Metabolism|
|State||Published - Feb 2006|
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Biochemistry
- Biochemistry, medical