THE EFFECT OF LOW IODINE DIET ON THYROID FUNCTION IN THE RAT*†

Abstract

IT HAS long been known that normal thyroid function is dependent upon an adequate intake of dietary iodine. In more recent years many studies have been made in an attempt to elucidate the exact role iodine plays in the development and function of the thyroid gland. The vast amount of data obtained on this subject has been amply discussed in many textbooks and review articles and will not be considered in detail in this report. In rats, as in most other vertebrates, thyroid changes develop when the dietary level of iodine is low. A deficiency in iodine intake produces a decrease in the synthesis of thyroid hormone and results in the formation of an hyperplastic goiter. The administration of iodine under such circumstances corrects this deficiency, and the gland assumes a more normal structure. In 1933 Levine, Remington and Von Kolnitz (1, 2) developed a low iodine diet which produced goiter in rats within five weeks. By the use of this diet and with replacement of iodine with potassium iodide, they concluded that the smallest amount of iodine necessary to prevent significant thyroid enlargement was from 1 to 2 micrograms per rat per day.