DETERMINATION OF IODINE COMPOUNDS IN SERUM. I. SERUM HYROXINE IN THE PRESENCE OF SOME IODINE CONTAMINANTS

Abstract

A column method utilizing the anion-exchange resin Dowex-1 is described for the determination of thyroxlne in serum. Values comparable to those for butanol-extractable iodine were obtained, and additions of in-organic iodine or iodotyrosines did not affect the reliability. An-alyses of sera containing in vitro additions of organic iodine compounds which interfere with the PBI and in most cases the BEI, gave results which suggested the possible usefulness of the column method. Furthermore, the pattern of thyroxlne elution with the column method, as determined by the iodine content of 3 successive 10-ml. fractions, was helpful in predicting the validity or nonvalidity of the result. When the BEI and column techniques were applied to cases in which elevated serum PBI values did not correlate with the clinical findings, there was some evidence for better specificity of the column method. Neither of the methods was helpful in most cases involving both inorganic iodine and PBI values in excess of 25 ug. per 100 ml.