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MBBS QUESTION #10334
Question 1
A patient with endemic goiter due to dietary iodine deficiency develops hypothyroidism. Iodine's essential biochemical role is that it is:
  • A structural atom incorporated directly into the thyroid hormones thyroxine (T4) and triiodothyronine (T3)✔️
  • Required strictly as a cofactor for TSH receptor signaling, without being part of the hormone itself
  • Necessary specifically for calcitonin synthesis
  • Required for parathyroid hormone synthesis
Correct Answer Explanation
Iodine is incorporated into tyrosine residues on thyroglobulin to form T3 and T4; insufficient dietary iodine limits thyroid hormone synthesis, triggering compensatory TSH-driven thyroid hyperplasia (goiter) in an attempt to trap more iodine and maintain hormone output.