Low-Iodine Diet for Producing Iodine Deficiency in Rats

Abstract

A low-iodine diet has been prepared for rats, using locally available low-iodine ingredients. On analysis it has been shown to consistently contain 15-20 ng iodine/g. When fed to growing female rats, this diet produced severe iodine deficiency while not significantly affecting growth or reproduction. The deficiency was manifested by a fall in daily urinary iodine excretion (to less than 1 JIg/day) and a seven-fold increase in thyroid uptake (1311) observable within 3 months. Levels of plasma thyroxine (T 4) and thyroid stimulating hormone (TSH) continued to change for 4-5 months, T 4 falling from 69·9 to 7·5 nmol/l and TSH increasing seven-fold from a control value of 364 to 2406 ng/ml. Goitre was present in all iodine-deficient rats and iodine content in the thyroid was 10 % of the control value.