A 49-year-old woman who had been treated with sodium levothyroxine because of hypothyroidism after diagnosis of Hashimoto thyroidits and total thyroidectomy for multinodular atoxic goiter was evaluated for persistent hypothyroidism despite the use of large doses of levothyroxine (600µg/day). The patient showed signs and symptoms of hypothyroidism and her laboratory tests were: TSH of 351µUI/mL, free thyroxine of 0.20ng/dL, and total triiodothyronine of 27ng/dL. She was submitted, under medical supervision, to a levothyroxine overload test with no evidence of malabsorption […]
