Synthesis of T3 and T4 depends on the availability of which chemical?

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Multiple Choice

Synthesis of T3 and T4 depends on the availability of which chemical?

Iodine is the chemical needed to make thyroid hormones. The thyroid takes up iodide from the blood and uses thyroid peroxidase to attach iodine to tyrosine residues on thyroglobulin, forming monoiodotyrosine and diiodotyrosine. These then couple to produce T3 and T4, which are stored and later released after thyroglobulin is broken down. Without iodine, this synthesis cannot proceed, leading to low T3 and T4 levels. The other minerals have supporting roles in related processes—selenium is crucial for deiodinases that convert T4 to T3 in tissues and for antioxidant protection in the thyroid, while iron and zinc are not the direct substrates required for thyroid hormone creation.

Iodine is the chemical needed to make thyroid hormones. The thyroid takes up iodide from the blood and uses thyroid peroxidase to attach iodine to tyrosine residues on thyroglobulin, forming monoiodotyrosine and diiodotyrosine. These then couple to produce T3 and T4, which are stored and later released after thyroglobulin is broken down. Without iodine, this synthesis cannot proceed, leading to low T3 and T4 levels. The other minerals have supporting roles in related processes—selenium is crucial for deiodinases that convert T4 to T3 in tissues and for antioxidant protection in the thyroid, while iron and zinc are not the direct substrates required for thyroid hormone creation.

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