Which element is required for the production of thyroid hormones?

Which element is required for the production of thyroid hormones?

• A. Sodium
• B. Iron
• C. Iodine
• D. Calcium

Answer: (C)

Thyroid hormones are made by attaching iodine atoms to the hormone precursor in the thyroid gland, so the element that must be present is iodine. Without iodine, the body can’t form T3 and T4 properly, which slows metabolism and can lead to issues like goiter or developmental problems. The other elements listed don’t become part of thyroid hormones—sodium is just a common extracellular ion, iron is used in many enzymes and oxygen transport, and calcium has roles in bones and signaling but isn’t incorporated into these hormones.

Thyroid hormones are made by attaching iodine atoms to the hormone precursor in the thyroid gland, so the element that must be present is iodine. Without iodine, the body can’t form T3 and T4 properly, which slows metabolism and can lead to issues like goiter or developmental problems. The other elements listed don’t become part of thyroid hormones—sodium is just a common extracellular ion, iron is used in many enzymes and oxygen transport, and calcium has roles in bones and signaling but isn’t incorporated into these hormones.