Rosh Internal Medicine Boost Practice Exam

Disable ads (and more) with a membership for a one time $2.99 payment

Study for the Rosh Internal Medicine Exam. Experience diverse and comprehensive questions with detailed explanations to solidify your understanding. Ace your examination today!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

What is the mechanism of action of propylthiouracil in treating thyroid storm?

Decreases adrenergic tone
Decreases vasomotor instability
Inhibits conversion of thyroxine to triiodothyronine
Inhibits release of thyroid hormone

The correct answer is: Inhibits conversion of thyroxine to triiodothyronine

Propylthiouracil (PTU) is effective in treating thyroid storm primarily due to its mechanism of inhibiting the conversion of thyroxine (T4) to triiodothyronine (T3). In the context of hyperthyroidism and particularly thyroid storm, there's an excessive release of thyroid hormones leading to severe symptoms. Propylthiouracil acts by blocking the enzyme deiodinase, which is responsible for this conversion. By reducing the levels of the more active hormone, T3, the drug helps in mitigating the physiological effects of hyperthyroidism, thus stabilizing the patient. Moreover, PTU also has an additional mechanism where it inhibits the synthesis of thyroid hormones by blocking the enzyme thyroid peroxidase, but its role in reducing T3 levels is crucial during acute management, particularly in life-threatening situations like thyroid storm. Understanding this mechanism underscores why propylthiouracil is a preferred choice in acute scenarios involving hyperthyroidism.