On thyroid protection against radioiodine

Radioisotopes of iodine continue to play an important role in experimental, diagnostic and therapeutic procedures in human health-care. Their use is ever increasing and, concomitantly, their accidental release and, hence, the occupational hazard to the workers and people around. Besides, the presence of a large number of nuclear reactors worldwide has increased this probability, so clearly evidenced by the Chernobyl accident. We have recently demonstrated that the major proportion of radioiodine (131I) induced damage to the thyroid could be curtailed by administering the stable iodide at 2h to 4h after its release. Since the thyroid gland is greatly at risk and it may not be possible to reach the affected population within this period in the event of an emergency, we designed a study to examine the efficacy and duration of thyroid protection by a single dose of stable iodide (potassium iodate-KIO3) given at 24 h post 131I exposure in rats. Thyroid uptake of 131I was found to increase from approximately 20% at 24h to 65% on the seventh day in control group, while it remained at the 24h level in KIO3 treated rats for the first four days and began rising slowly from the fourth day onwards, suggesting the need for readministration of stable iodide. (author)