Hormones of thyroid gland in sera of rats treated with different dose of concentrated potassium iodine solutions.

Introduction: Potassium iodine (KI) is used as a drug therapy for treating numerous diseases such as small-vessel vasculitis, erythema nodosum, vasculitis nodularis, Sweet's syndrome, tuberculosis and granulomatosis, and for iodized salt. At the same time, KI can be harmful. Iodine intake may increase the frequency of thyroiditis in humans, and may induce the occurrence of experimental thyroiditis (ET) in animals. Investigations on an experimental model for the examination of thyroiditis in Wistar rats have clearly showed morphological changes in the rat thyroid evoked by KI administration.

Objective: The purpose of this study was to compare the effects of low and high doses of KI on the thyroid gland of Wistar rats and determine the effect on hormone status (T4, T3 and TSH) in this rat strain.

Methods: Two groups of rats from the Wistar strain were treated with a low iodine dose (225 microg/g BW) and with a high iodine dose (675 microg/g BW) of KI solutions. Untreated nonimmunized animals served as controls. The solution was administrated daily intraperitoneally during the period of 26 consecutive days.

Results: Monitoring hormone status (TSH, T3 and T4) and morphological changes it was found that therapeutic doses of KI applied in treatment induced the occurrence of experimental thyroiditis (chronic destructive Hashimoto's thyroiditis in humans) and cell necrosis in animals not carrying a genetic susceptibility. Significant inflammatory changes were observed in rats treated with a high iodine dose.

Conclusion: The early iodine induced cell necrosis and inflammation in the nonimmunized animals without genetic susceptibility is a new experimental model of thyroiditis.