Thyroid Dysfunction (Hyperthyroidism or Hypothyroidism)

Excessive iodine intake can trigger or worsen hyperthyroidism or hypothyroidism, particularly in those with pre-existing thyroid issues. This disruption stems from iodine's impact on thyroid hormone production.

Excessive iodine intake can disrupt normal thyroid function, leading to either hyperthyroidism (overactive thyroid), characterized by symptoms such as weight loss, rapid heartbeat, anxiety, and heat intolerance, or hypothyroidism (underactive thyroid), with symptoms including weight gain, fatigue, depression, and cold intolerance. The effect is most pronounced in individuals with pre-existing thyroid conditions like Hashimoto's thyroiditis or Graves' disease, or those living in iodine-deficient areas who are then exposed to a sudden, large increase in iodine. The pathophysiology involves the Wolff-Chaikoff effect (inhibition of thyroid hormone synthesis by high iodine levels, leading to hypothyroidism) and the Jod-Basedow phenomenon (iodine-induced hyperthyroidism, especially in autonomously functioning thyroid tissue).