Comparison of L-thyroxine and a saturated solution of potassium iodide in preventing damage to the thyroid following iodine-131-labeled antibody injection.

Following injection of radioiodinated antibodies in diagnostic amounts, there is variable uptake of radioiodine by the thyroid. Unless preventive steps are taken, radiation damage to the gland may occur. We have evaluated the role of L-thyroxine and a saturated solution of potassium iodide (SSKI) in preventing radiation damage to the thyroid glands of Sprague-Dawley adult male rats by measuring DNA strand breakage by the nucleoid sedimentation gradient method. Pretreatment with SSKI reduced DNA damage and also reduced 131I accumulation in the thyroid. Pretreatment with L-thyroxine also reduced DNA damage without significantly reducing 131I accumulation in the thyroid. The possible mechanisms of action of L-thyroxine and SSKI in preventing radiation damage to the thyroid are addressed.