Why can iodine deficiency cause a goitre?

Iodine is an essential nutrient required for the production of thyroid hormones. When dietary iodine intake is insufficient, the body cannot produce these hormones in adequate amounts.12

In response to low hormone levels, the pituitary gland increases the secretion of thyrotropin, also known as thyroid-stimulating hormone (TSH). This hormone serves two primary purposes: it stimulates the thyroid to capture more available iodine for hormone synthesis, and it promotes the growth of thyroid cells.12

While this compensatory mechanism attempts to maintain normal hormone production, the resulting stimulation of thyroid cell growth leads to an enlargement of the thyroid gland, a condition known as goitre.12