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
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