Effects of thyroxine withdrawal in biochemical parameters and cardiac function and structure in patients with differentiated thyroid cancer.

Aim: Patients with differentiated thyroid carcinoma (DTC) are closely monitored during the first decade after diagnosis. At intervals of 1-2 years withdrawal of suppressive doses of T(4) is recommended in order to check thyroglobulin (Tg) levels under increased TSH. T(4) therapy is usually withdrawn for 5 weeks (during the first 3 weeks patients receive treatment with T(3) instead of T(4), and the last 2 weeks stop all medication).