Question

The synthesis of thyroxine T4 in the human body requires

• A. Selenium
• B. Iodine
• C. Iron
• D. Zinc

Hint:

Remember: {Iodine deficiency leads to goiter and hypothyroidism} due to impaired thyroid hormone synthesis.

Answer 1

The Correct Option is B

Step 1: Role of iodine in thyroid hormone synthesis.
- Thyroxine (T4) and triiodothyronine (T3) are produced in the thyroid gland.
- Both hormones require iodination of tyrosine residues in thyroglobulin.
- Iodine is an essential trace element incorporated directly into the structure of T4 (which contains 4 iodine atoms).
Step 2: Eliminate other options.
- Selenium: important for deiodinase enzymes (conversion of T4 to T3), not for synthesis.
- Iron: important for hemoglobin and some enzymes, not for T4 synthesis.
- Zinc: important for enzyme activity and transcription factors, not for thyroid hormone synthesis.
Therefore, thyroxine T4 synthesis requires iodine.