Wolff-chaikoff effect is ?
Reduced thyroxine synthesis by radiotherapy
Reduced thyroxine synthesis by propylthiouracil
Reduced thyroxine synthesis by iodides
None of the above
Ans. is 'c' i.e., Reduced thyroxine synthesis by iodides Iodine and Iodides Iodine is the fastest acting thyroid inhibitor. Most impoant action is inhibition of hormone release (thyroid constipation); but all facets of thyroid synthesis may be affected. Excess iodide inhibits its own transpo in thyroid cells and may alter the redox potential of cells, thus interfering iodination -reduced TIT3 synthesis ( Wolffichaikoff effect).