A 31-year-old woman comes to the physician for palpitations, and anxiety. During this time, she has had a 2-kg (4.4-lb) weight loss. The patient has no prior medical problems and takes no medications. Blood pressure is 140/70 mm Hg and pulse is 120/min. Physical examination shows a diffusely enlarged, warm thyroid gland. There is a fine tremor in her outstretched hands. ECG shows sinus tachycardia. Serum TSH is decreased and free thyroxine (T4) is increased. The patient is treated with multiple drugs, including propranolol. In addition to its beta-adrenergic receptor-blocking activity, this drug is likely to decrease which of the following?

Question

A 31-year-old woman comes to the physician for palpitations, and anxiety. During this time, she has had a 2-kg (4.4-lb) weight loss. The patient has no prior medical problems and takes no medications. Blood pressure is 140/70 mm Hg and pulse is 120/min.  Physical examination shows a diffusely enlarged, warm thyroid gland.  There is a fine tremor in her outstretched hands.  ECG shows sinus tachycardia.  Serum TSH is decreased and free thyroxine (T4) is increased.  The patient is treated with multiple drugs, including propranolol.  In addition to its beta-adrenergic receptor-blocking activity, this drug is likely to decrease which of the following?

Quizplus · Accepted Answer

Eductional Objective: Hyperthyroidism causes upregulation of beta-adrenergic receptor expression, leading to increased catecholamine effect.  Beta blockers are used to blunt the adrenergic manifestations of hyperthyroidism.  In addition, lipid-soluble beta blockers reduce conversion of T4 to T3 by inhibiting 5'-monodeiodinase in peripheral tissues.

A 31-Year-Old Woman Comes to the Physician for Palpitations, and Anxiety