Urinary Excretion of Radioactive Iodine,I 131,in a Case of Severe Hyperthyroidism. ∗

Abstract

Summary

Information is given of the urinary excretion of radioactive iodine following administration of relatively large doses in a patient with severe hyperthyroidism. Administration of stable iodine (in Lugol's solution) after the urinary excretion of I¹³¹ had reached a low level resulted in a pronounced increase in this excretion, which lasted some 48 hours after discontinuing Lugol's solution. This increase in excretion of I¹³¹ was not observed following administration of Lugol's solution in one case of carcinoma of the thyroid with metastasis. Retention of 85% of the I¹³¹ by the thyroid agrees with other figures on the retention of I¹³⁰ by the hyperplastic thyroid, when iodine has been withheld for a period of over 4 weeks prior to radioactive iodine.‡