Lack of influence of povidone-iodine on tests of thyroid function.

The external application of povidone-iodine, an antiseptic agent, was tested for its influence on thyroid function. Previous workers have described some in vitro changes in thyroid function tests following its use. In the present study topical application of povidone-iodine did not affect thyroid function as measured some days later using both in vivo and radio-active iodine in vitro test methods, despite the fact that the latter are notorious for being influenced by exogenous iodine.