Radioactive Iodine as an Indicator in Thyroid Physiology. Iv. The Metabolism of Iodine in Graves' Disease 1

Abstract

The use of radioactive iodine as an indicator in thyroid physiology has been described by Hertz, Roberts and Evans (1) and by Hertz, Roberts, Means and Evans (2, 3). Hamilton and Soley (4) have published data obtained by the use of radioactive iodine on goiter patients of several types.We have administered radioactive iodine The procedure for each uniodinized patient was as follows: The basal metabolic rate was determined after a preliminary period of bed rest. Labelled iodine was then administered by mouth, and urines were collected in 12 cases. The uptake of labelled iodine by the thyroid was measured for 13 patients at various times after administration of the labelled iodine by means of an externally placed Geiger-Muller counter. No further iodine was given until these external measurements indicated that the thyroid iodine level had reached a relatively constant value. At this time routine iodinization (minims 5 saturated solution of KI, twice daily) was begun. When maximal metabolic and clinical response had been reached 6 to 10 days later, 19 patients were subtotally thyroidectomized and an estimate of the residual thyroid tissue was made. A small portion of the excised gland was reserved for histologic study, and the remainder was fractionated chemically. The two fractions obtained, which we call "T" and "D" according to the notation of Salter (6), represent the thyroxine-like and diiodotyrosine-like fractions of the thyroid iodine. These fractions were assayed for both ordinary (total) iodine content and for labelled iodine.The labelled iodine excreted in the urine was determined for most patients during the first few days following the administration of labelled iodine. Labelled blood iodine was determined in a few cases.Cases 1, 2, 3, 4, 5, 9, and 10 received ordinary iodine prior to the administration of the labelled dose. The interval of preiodinization given in Table I is the time between the first dose of ordinary iodine and the dose of labelled iodine. In only one of these cases, Case 10, was the patient totally iodinized by clinical standards before the administration of the labelled dose.Cases 16 and 28 were normal persons and were, of course, not operated upon. In addition, Cases 15, 17, and 22 were not operated upon for clinical reasons.The details of individual iodinization procedure are given in Table I. The first clinical experiments were designed to afford data on the thyroid uptake from a labelled dose of iodine at various degrees of iodinization 25

The Behavior of Radioiodine in the Blood 1

“…The quantity of radioiodine collected by the thyroid has been determined directly by in vivo measurements (Hamilton, Sole-and co-workers [1][2][3][4]; Hertz and co-workers [5] ), and indirectly by estimations from the total quantity excreted in the urine over a fixed period (Hertz and coworkers [5]; Rawson and co-workers [6,7]). The distribution of iodine in the thyroid has been studied by autoradiograms (3) or by chemical analysis of excised tissue (5).…”

Comparisons of the Distribution of Radioactive Iodine in Serum and Urine in Different Levels of Thyroid Function

“…The failure of the latter investigators to administer any carrier iodine might account for some of the difference in results. Whereas some investigators (3,4) have measured the excretion of radioiodine in the urine as an index to the quantity retained in the thyroid gland, a poor correlation has been found (13) between determinations of this type and direct measurements over the thyroid. However, all of the other clinical tests of thyroid function are beset with difficulties.…”

“…(Received for publication March 19, 1948) One of the earliest uses of radioiodine was as a tool for the study of thyroid physiology (1)(2)(3)(4)(5)(6)(7). Estimations of the relative quantities of isotope stored in the thyroid have been made by means of a Geiger-Muller tube held over the gland and by determining the amount present in the urine and blood.…”

Effective method of measuring the radioactivity of ‐capsule prior to radioiodine therapy with significant reduction of the radiation exposure to the medical staff

“…Radioiodine therapy was first performed in the early forties of the last century 1 , 2 and until now, it was a safe and effective method for the treatment of benign and malign diseases of the thyroid gland. In most cases, the radioiodine required for the therapy is administered as a capsule containing $false[{\hspace{0.17em}}^{131}\mathrm{I}false]$iodid.…”