CC824 The Medical Research Center Brookhaven National Laboratory 401846 Upton, L. L, New York Elevation of the Serum Protein-Bound Iodine Level in Inhabitants of the Marshall Islands J. E. RALL, M.p. and R. A. CoNARD, M.D. Upton, New York Bethesda, Maryland re years ago, in the course of follow-up examinations of some inhabitants of the ' Marshall Islands who had been exposedto fallout radiation from a 1954 hydrogen bombexplosion, a high incidence of unexplained elevation of the serum protein-bound iodine (PBI) level was found in both exposed and unexposed subjects [7]. The present report describes various studies of the kinetics of iodine metabolism in these subjects and some further work on the nature of the serum iodine. MATERIAL AND METHODS The people studied are all inhabitants of the Marshall Islands, most of them from the single atoll of Rongelap. To the best of our knowledge there has been little outbreeding. In some instances the results of radiated. and control populations will be presented separately. All results reported in this article are from healthy persons who received no medication. Normal values for the fractionation of serum iodine by chro- were eluted with 10 M acetic acid. Urinary iodine determinations were performed by the Boston Medical Labgratory. In several instances the capacity of thyroxine-binding alpha globulin (TBG) was measured by a method described previously [5]. Studies with I" were performed using a well- collimated 1 inch sodium iodide crystal at 25 cm. for the patient’s neck. The I™ was milked daily from tellurium'™ bound to a resin by elution with 0.1M NH,OH.It was calibrated against a Cs'* standard. The F® was administered orally before breakfast. Counts were obtained over the neck at approximately 14, 1, 2, 3 and 4 hours, and a single 3 hour urine specimen was assayed for I'® content. In all instances a count of the neck was performed before the ['* dose was given since a small amount of what was presumed to be Cs!" increased the backgroundslightly. Mathematical analysis of these data used an IBM 7094 computer and the program of Berman etal. [6]. No experimental correction for extrathyroidal radioactivity “‘seen’? by the counter was made since the computer program adjusted the readings over the neck for this factor. A least squares best fit assuming exponential thyroid uptake and renal excretion of iodide produced a “best” value for this factor, termed on. We are indebted to Dr. Mones Berman for this analysis. matography were obtained on blood drawn from normal volunteer subjects at the Clinical Center, National Institutes of Health. The serum protein-bound iodine was determined by the method of Foss et al. [2] by Brookhaven National Laboratory, by the Boston Medical Laboratories and by Bioscience Laboratories. In addition, values for RESULTS The results of analyses for iodine in serum are shown in Table 1. It is apparent that throughout several years and with several different methods, the average serum protein- butanol-extractable iodine (BEI) of serum are available, obtained by Bioscience Laboratories. Column chromatography of the serum iodine was also performed by Bioscience Laboratories, using a modification of the method of Galton and Pitt-Rivers [3,4]. In this method the serum is adjusted to pH 10.0 with 0.8N NH,OH and placed in a previously washed Dowex 1 by 2, 200 to 400 mesh column which had been treated with 0.8N NH,OH until the pH of the eluate reached 10.9. A ratio of 4 ml. of serum to 8 ml. of resin is used. The first elution is with distilled water and yields the iodoprotein fraction. Experiments with labeled L-thyroxine added to serum showedthat less than 5 per cent of the thyroxine appeared in this fraction. Thyroxine (T,) and triiodothyronine (T3) boundiodine level in the inhabitants of Ronge- lap is higher than normal and that the values in from 16 to 64 per cent of the natives are above the normal range by American standards. The first results showing an elevated PBI level were obtained in 1958 and since that time repeated efforts have been made to ensure that glassware and syringes were not contaminated with iodine. The absence of contamination can be seen by the fact that * From the National Institute of Arthritis & Metabolic Diseases, National Institutes of Health, Bethesda, Maryland and Brookhaven National Laboratory, Upton, Long Island, New York. Manuscript received October 22, 1965. VOL. 40, JUNE 1966 BNL RECORDS 883 REPOSITORY cottection LIARSHALL ISLANDS. BOX Ne, MEQICAS OFPT FoLpen — 44 = 3 73 | fH~ 8 PUBLICATIONS { f : | ! } |