RESUMO
Thyrotropin (TSH) suppression therapy using thyroid hormone plays an important role in the management of patients thyroidectomized for differentiated thyroid cancer. The rationale for TSH suppression is that differentiated thyroid cancer cells have TSH receptors and show increased adenylate cyclase activity following TSH exposure. L-thyroxine is used for long-term therapy. L-triiodothyronine is preferred when suppressive therapy must be discontinued for radioiodine scan, since its shorter half-life allows more rapid increases of TSH levels. The assessment of TSH suppression is still uncertain. The development of second and third TSH assay generations with progressive improvement in sensitivity has made the TRH test unnecessary and has raised the issue of the TSH level indicative of TSH suppression. In clinical practice TSH values below 0.1 mU/L are considered compatible with appropriate TSH suppression. Serum thyroglobulin is a reliable marker of metastatic disease after total surgical and radioiodine ablation of the thyroid gland and it is useful in the surveillance of patients with differentiated thyroid cancer.
