Recombinant human thyrotropin in follow-up of patients with differentiated thyroid cancer.

BACKGROUND: Despite very good prognosis patients with previously treated well-differentiated thyroid cancer (DTC) require lifelong monitoring for recurrent disease. Apart from neck ultrasonography (USG) two diagnostic tests play a central role in follow-up of these patients: radioiodine whole body scanning and serum thyroglobulin (Tg) measurement. The diagnostic value of both tests is most accurate during thyroid stimulating hormone (TSH) stimulation. Temporary discontinuation of thyroid hormone therapy was previously the sole effective approach for TSH-stimulated testing. However, hormone withdrawal was associated with the morbidity of severe hypothyroidism. The introduction of recombinant human TSH (rhTSH)-stimulated testing offers an alternative way. 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 and to report the first experience with this diagnostic procedure in Slovakia.

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 4 patients (2 women and 2 men) 5, 9, 12 and 38 years after 1311 treatment with a mild suspicion of DTC recurrence.

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 4 patients (4.8%) and Tg in the range 0.6-2 ng/ml in 3 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: In accordance with the literature rhTSH-Tg concentration in combination with neck USG has the highests sensitivity and negative predictive value in detecting residual or recurrent DTC (Tab. 1, Fig. 1, Ref. 14). Full Text (Free, PDF) www.bmj.sk.