[Thyroxine replacement therapy in patients with thyroid cancer and thyroid hormone resistance syndrome].

Resistance to thyroid hormone (RTH) is a genetic syndrome defined by an impaired sensitivity to thyroid hormones. It is characterized by discrepancies between the blood levels of thyroid hormones (FT3, FT4) and TSH, and by the coexistence of hypothyroidism and hyperthyroidism symptoms. Here we describe the case of a patient affected with thyroid cancer and RTH in whom it was difficult to obtain a good control of TSH after total thyroidectomy despite high doses of thyroxine replacement therapy. This represents a unique model to improve the understanding of the alterations in the feedback mechanism in patients with RTH and to optimize the replacement therapy in patients with concomitant thyroid cancer who need adequate TSH control.