Video narration
How does iodine from iodized table salt become a thyroid hormone? Think of salt as delivering raw material, not a finished product. In your gut, iodine is absorbed mainly as iodide, then carried in blood to the thyroid. Thyroid cells capture iodide and move it into the follicle's colloid, the storage space inside the gland. Here's the crucial turn: iodide does not directly become a hormone. Thyroid peroxidase activates it and attaches iodine to tyrosines on thyroglobulin, a thyroid protein. One attachment forms MIT; two form DIT. These building blocks couple: MIT plus DIT makes T3, while DIT plus DIT makes T4. The hormones stay stored on thyroglobulin until release into your blood; TSH helps stimulate the process. So how does salt iodine become hormone? Only after absorption as iodide, thyroid transport, enzyme-driven attachment, and coupling-raw material processed into T3 and T4.