What happens when there is a deficiency of iodine in the diet?

When there is a deficiency of iodine in the diet, the most significant consequence is the development of a goiter. Iodine is essential for the synthesis of thyroid hormones, particularly thyroxine (T4) and triiodothyronine (T3), which are critical for regulating metabolism and overall growth and development in the body. When there is insufficient iodine, the thyroid gland cannot produce adequate amounts of these hormones.

As a result, the body compensates for the low hormone levels by stimulating the thyroid-stimulating hormone (TSH) from the pituitary gland, which prompts the thyroid gland to grow in size, leading to the formation of a goiter. This enlargement is a physical manifestation of the thyroid trying to capture more iodine and increase hormone production, but without sufficient iodine to use, the cycle perpetuates.

While the other options listed present various health issues, they are not directly related to iodine deficiency. For example, decreased adrenal function more commonly pertains to adrenal gland-related issues, insulin shock is related to problems with insulin regulation often in diabetes, and calcium imbalance typically involves issues with parathyroid hormone or vitamin D. Therefore, goiter development is the direct and well-documented effect of iodine deficiency.