Serum Thyroglobulin Concentrations and 131I Whole-Body Scan Results in Patients with Differentiated Thyroid Carcinoma After Administration of Recombinant Human Thyroid-Stimulating Hormone

The use of recombinant human thyroid-stimulating hormone (rhTSH) has recently become available as an alternative diagnostic tool to assess the persistence and recurrence of differentiated thyroid carcinoma (DTC) in patients on thyroid hormone-suppressive therapy (THST) after near-total or total thyroidectomy and ablative doses of 131 I. We report the results of rhTSH administration in patients who were monitored for DTC. Methods: Thirty-three adult DTC patients (13 men, 20 women; mean age ± SE, 45.6 ± 2.31 y; age range, 21-65 y) underwent diagnostic follow-up after rhTSH administration at a dose of 0.9 mg once a day for 2 d. Whole-body scanning and serum thyroglobulin (Tg) measurement were performed after rhTSH administration. Patients were divided into 2 groups depending on serum Tg concentrations on THST: 29 patients had Tg concentrations of 2 ng/mL (group B). Results: In group A, Tg values remained at <2 ng/mL in 25 patients and increased from 1.1 ± 0.14 ng/mL to 22.0 ± 5.75 ng/mL (mean ± SE) in 4 patients after rhTSH administration. Whole-body scanning did not reveal any uptake of 131 I in the 25 patients without an increase in Tg, whereas 131 I uptake was evident in 2 of the 4 patients with a rise in Tg. In group B, Tg values increased in all 4 patients from 17.3 ± 6.35 ng/mL to 55.3 ± 12.75 ng/mL, and 131 I uptake was evident in 3 of the 4 patients. No major adverse effects were reported after rhTSH administration. Conclusion: Our results show that the measurement of serum Tg concentrations after rhTSH has a higher diagnostic value than whole-body scanning in detecting the persistence of thyroid tissue. Therefore, rhTSH should be administered in TSH-suppressed patients with basal serum Tg concentrations of <2 ng/mL because the increment in serum Tg concentrations may reveal the persistence of thyroid tissue in these patients.