Wolff-Chaikoff effect

Last revised by Daniel J Bell on 23 Sep 2018

Wolff-Chaikoff effect is an autoregulatory phenomenon, whereby a large amount of ingested iodine acutely inhibits thyroid hormone synthesis within the follicular cells, irrespective of the serum level of thyroid-stimulating hormone (TSH) 1


The Wolff-Chaikoff effect is thought to be transient, with the thyroid gland returning to its near-normal hormone synthesis in 26-50 hours in normal subjects 2. It provides temporary protection against the thyroid gland synthesizing an excessive quantity of thyroid hormones in states of excess iodine. However, it can also lead to hypothyroidism in susceptible patients with underlying thyroid disease, who can experience a delayed “escape” from the Wolff-Chaikoff effect.

History and etymology

This effect was first reported in 1948 by Jan Wolff and Israel Chaikoff, who noticed a decrease in the organic binding of iodine, when plasma iodide levels were elevated 3.

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