THE EFFECT OF EXOGENOUS THYROXINE ON RADIO-IODINE UPTAKE IN NORMAL SUBJECTS AND IN CASES OF THYROTOXICOSIS IN REMISSION

Abstract

Radio-iodine uptake has been measured by the neck/thigh ratio, before and at the end of a course of oral sodium-l-thyroxine 0·4 mg. given daily for two weeks. Twenty normal subjects, thirteen patients with non-toxic goitres and thirteen patients who had recovered from thyrotoxicosis have been studied in this way. In all three groups there was a significant fall in the neck/thigh ratio while the subjects were taking thyroxine. The mean fall of the neck/thigh ratio after taking thyroxine did not differ significantly in the normal and recovered thyrotoxic groups. These results do not support the idea that failure to respond to thyroxine is a constitutional feature of subjects who have had an attack of thyrotoxicosis.