Endocrine Abstracts

Background: Despite good prognosis patients with previously treated well-differentiated thyroid cancer (DTC) require lifelong monitoring for recurrent disease. The diagnostic value of radioiodine whole body scanning and serum thyroglobulin (Tg) measurement is most accurate during thyroid stimulating hormone (TSH) stimulation. The introduction of recombinant human TSH (rhTSH)-stimulated testing offers the possibility to avoid hormone withdrawal associated with the morbidity of severe hypothyroidism. Recent clinical trials have shown that measurement of the rhTSH-stimulated serum Tg concentration (rhTSH-Tg) alone is the most sensitive way to detect residual or recurrent thyroid cancer.

Objectives: The aim of the study was to investigate rhTSH-Tg in patients considered to be cured with already finished radioiodine treatment 1–3 years ago (routine follow-up) and in patients more years after radioiodine therapy with a new indefinite (mild) suspicion for DTC recurrence.

Patients and methods: RhTSH-Tg was examined in 84 patients (72 women and 12 men) clinically free of disease, 1–3 years after finishing radioiodine therapy. Second group consisted of four patients (2 women and 2 men) 5, 9, 12 and 38 years after ¹³¹I treatment with a mild suspicion of DTC recurrence based on routine neck ultrasonography (USG).

Results: RhTSH testing was well tolerated. No adverse events were detected. In the first group clinically free of disease undetectable rhTSH-Tg (( 0.2 ng/ml) was found in 77 patients (91.7%), Tg above diagnostic cutoff (( 2 ng/ml) in four patients (4.8%) and Tg in the range 0.6–2 ng/ml in three cases (3.6%). In all patients of second group previous indefinite suspicion of DTC recurrence was confirmed by the rhTSH-Tg rise (2.9–7.3 ng/ml).

Conclusion: We detected persistent disease in 4.8% of patients considered to be cured and confirmed recurrent disease in all patients wild mild USG suspicion. In accordance with the literature rhTSH-Tg concentration in combination with neck USG has the highest sensitivity and negative predictive value in detecting residual or recurrent DTC.