Biliary and Urinary I 131 Excretion in Euthyroid,Hyper- and Hypothyroid Rats Injected with Labeled Thyroxine

Abstract

Summary

Biliary and urinary excretion of radioiodine was studied following subcutaneous injection of tracer amounts of I¹³¹-labeled thyroxine in normal, hypo- and hyper-thyroid rats. Thyroidectomized and thiouracil-treated groups showed reduced biliary radioiodine elimination, as well as diminished bile volume during the 6-hour collection period. Hyperthyroid animals showed a marked increase, thiouracil-treated animals a decrease in urinary excretion of radioactive iodine over a 12-hour period. Radioiodine excretion in both bile and urine tended to be lower in the thiouracil-treated animals than in the thyroidectomized groups.