Ace the Certified Emergency Nurse (CEN) Challenge 2025 – Energize Your Nursing Future!

The correct choice is PTU (propylthiouracil), which is a medication specifically designed to inhibit the synthesis of thyroid hormones. It accomplishes this by blocking the enzyme thyroperoxidase, which plays a crucial role in the production of thyroid hormones in the thyroid gland. By inhibiting this enzyme, PTU effectively decreases the synthesis of both thyroxine (T4) and triiodothyronine (T3), which are vital hormones in regulating metabolism.

In contrast, levothyroxine is a synthetic form of the thyroid hormone thyroxine and is used to treat hypothyroidism, making it counterproductive in the context of reducing thyroid hormone synthesis. Propranolol primarily acts as a beta-blocker and is often used to manage symptoms of hyperthyroidism, such as rapid heart rate, but it does not affect the production of thyroid hormones directly. Glucagon is a hormone that raises blood glucose levels and is involved in carbohydrate metabolism, with no role in modulating thyroid hormone synthesis.