Biliary and Urinary I131 Excretion in Euthyroid, Hyper- and Hypothyroid Rats Injected with Labeled Thyroxine

Abstract

Thyroidectomized and thiouracil treated groups showed reduced biliary radioiodine elimination, as well as diminished bile vol. during a 6-hr. collection period after subcut. injn. of tracer amts. of I131 labeled thyroxine. Desiccated thyroid treatment resulted in an increase in the bile vol. but no change in the percentage of injd. activity excreted in the bile. The vol. of bile appears to be directly related to whole animal metabolism. Hyperthyroid animals showed a marked increase, thiouracil-treated animals a decrease in urinary excretion of I131 over a 12-hr. period. Radioiodine excretion in both bile and urine tended to be lower in the thiouracil treated animals than in the thyroidectomized groups.