[Influence of topically applied iodides on urinary iodine excretion and thyroid function]

The present study was undertaken, to evaluate whether ophthalmic drug, containing iodine applied to conjunctival sac might result in a significant increase of urine iodine excretion and thus might be indirectly associated with the risk of iodine-induced hyperthyroidism. The aim of the study was to examine the occurrence of biochemically relevant changes in urine iodine excretion and in thyroid function after topical administration of ophthalmic drug containing iodine.

In the study twenty-two patients without a history of thyroid disease were examined. The Vitreolent (Ciba Vision) was applied topically to conjunctival sac four times a day for one month. The urinary iodine excretion, using "Rapid Urinary Iodine Test" (Merck KgaA) and parameters of thyroid function (TSH, FT3, FT4) were measured before starting and after therapy.

The data showed, that was a significant increase in urinary iodine excretion at the end of therapy; as far as thyroid function was concerned, neither changes in level of TSH nor thyroid hormones were observed.