Question

Conversion of T4 to T3 inhibition is associated with

• A. Propylthiouracil
• B. Radioactive iodine
• C. Lugol's iodine
• D. Carbimazole

Answer 1

The Correct Option is A

The question pertains to the pharmacological aspect of drugs that affect thyroid hormone levels. Specifically, it asks which substance is associated with the inhibition of the conversion of thyroxine (T4) to triiodothyronine (T3).

Let's analyze the options:

1. Propylthiouracil: This drug is an antithyroid agent that works by inhibiting the enzyme thyroid peroxidase, as well as inhibiting the conversion of T4 to T3 peripherally. Therefore, Propylthiouracil is the correct answer since it directly inhibits T4 to T3 conversion.
2. Radioactive iodine: It is used to destroy thyroid tissue by radiation to treat hyperthyroidism, but it does not directly inhibit the conversion of T4 to T3.
3. Lugol's iodine: This is a strong iodine solution used in various medical applications, including reducing thyroid hormone secretion temporarily, but it does not inhibit the peripheral conversion of T4 to T3.
4. Carbimazole: This is an antithyroid drug that is a precursor to methimazole in the body, which inhibits thyroid peroxidase but does not inhibit the conversion of T4 to T3.

After evaluating all the options, the successful inhibition of the conversion of T4 to T3 is uniquely performed by Propylthiouracil. Therefore, the correct answer is Propylthiouracil.