Discrepancy between the Distributions of Iodine in Human Serum when estimated by Iodine-131 and Iodine-127

Abstract

IN spite of indications to the contrary¹, it is generally assumed that only traces of iodotyrosines are normally present in circulating blood of human beings and animals^1,2. This assumption is based on the distribution of the labelled iodoamino-acids observed after administration of iodine-131. Roche and Michel¹ state: “Thyroid hormone must be considered as being a mixture of L-thyroxine and L-3,5,3′-triiodothyronine and containing at least 90 per cent of the total plasma iodide”. Previous work with stable iodine, however, suggests otherwise³.