A 27-year-old woman comes to the physician because of a 2-month history of palpitations, diaphoresis, and a 5-kg (11-lb) weight loss. The patient has no other medical problems and takes no medication. She does not use tobacco, alcohol, or illicit drugs. Her pulse is 101/min and blood pressure is 141/84 mm Hg. Physical examination shows a diffusely enlarged of thyroid gland and nontender on palpation and a fine tremor when the fingers are outstretched. Laboratory studies show markedly decreased serum TSH and elevated thyroxine levels. Methimazole monotherapy is initiated. Two months later, her symptoms had resolved. The treatment most likely improved this patient's condition by directly inhibiting which of the following processes?

Question

A 27-year-old woman comes to the physician because of a 2-month history of palpitations, diaphoresis, and a 5-kg (11-lb) weight loss. The patient has no other medical problems and takes no medication.  She does not use tobacco, alcohol, or illicit drugs.  Her pulse is 101/min and blood pressure is 141/84 mm Hg. Physical examination shows a diffusely enlarged of thyroid gland and nontender on palpation and a fine tremor when the fingers are outstretched. Laboratory studies show markedly decreased serum TSH and elevated thyroxine levels.  Methimazole monotherapy is initiated.  Two months later, her symptoms had resolved.  The treatment most likely improved this patient's condition by directly inhibiting which of the following processes?

Quizplus · Accepted Answer

Eductional Objective: Thioamides (eg, methimazole, propylthiouracil) decrease the formation of thyroid hormones via inhibition of thyroid peroxidase, the enzyme responsible for both iodine organification and coupling of iodotyrosines.  Propylthiouracil also decreases the peripheral conversion of T4 to T3.

A 27-Year-Old Woman Comes to the Physician Because of a 2-Month