Precipitable Iodine Research Articles

Therapeutic Effects in Hyperthyroidism from Repeated Diagnostic Doses of I131

Several repeated tracer doses of I131Sare commonly used to follow the course of hyperthyroidism under treatment of various types. While it is generally assumed that these tracer amounts of the isotope are innocuous, evidence from three directions has suggested the need to test this assumption. The first observation in this clinic in conflict with the commonly accepted concept has been the consistent reporting by occasional patients with toxic goiter that they “felt better” following a diagnostic tracer test. The obvious explanation has been the facile one, that a factor of suggestion is involved. This has not always appeared adequate. The second cause for suspicion of a possible effect from tracer dosage is the finding that there is a wide biological variability in response to therapeutic doses of I131 in hyperthyroidism (1). Extreme sensitivity of the thyroid to internal radiation effect has been noted, as well as extreme resistance. As a consequence, it has appeared reasonable that smaller dosages of I131 than those used therapeutically might have some effect. This lower dosage range has remained unexplored since the failure of Soley and Miller to achieve remissions with doses of 250 microcuries repeated several times (2). Finally, interest in a possible effect from tracer dosage has been aroused by the conflict in results between groups investigating the effect of ACTH upon hyperthyroidism (3, 4, 5). The only apparent difference in procedure has been the number of tracer tests and the size of the dose of I131 used in each test. For these reasons, then, the present investigation was undertaken to determine the effect upon hyperthyroidism of several tracer doses of I131. It has been found that complete remission of thyrotoxicosis may result from as little as 240 microcuries I131, total dosage. The time interval from the beginning of the experiment to the achievement of remission has, in most instances, paralleled that of therapeutic doses of I131. The remissions following smaller dosage generally have been transient. Methods The methods employed by this laboratory for tracer testing with I131 and for direct measurement over the thyroid of uptake of the isotope at twenty-four hours have been described in detail elsewhere (6). In all cases the diagnosis was made and the patient was followed from the clinical and laboratory standpoints as previously detailed (7). Only patients with unquestioned hyperthyroidism due to toxic diffuse or toxic recurrent goiter were used in the present study. It should be pointed out that the series includes several children. These were deliberately treated after an initial observation indicated the possibility, in this age group, of unusual susceptibility of the thyroid to radiation effect. Basal metabolic rate determinations were conducted with the use of a Benedict Roth apparatus. Serum precipitable iodine was estimated by the method of Barker (8).

Protein-bound iodine in serum of rats receiving iodide or iodine with or without goitrogen.

DVOSKIN&S studies with elemental iodine (1, 2, 3) clearly established that injections of this form of the halogen were as effective as thyroxine or desiccated thyroid in cancelling the inhibition of growth which followed thyroidectomy or goitrogen therapy in immature rats. Subsequently Barker showed that administration of elemental iodine by the subcutaneous route produced marked elevations of the protein-bound or precipitable iodine in the plasma of rats and in the tissues at the sites of injection (4, 5). In the experiments reported by Dvoskin, parenteral or oral inorganic iodide proved to be essentially inert in restoring or maintaining normal growth rates in hypothyroid or athyroid rats. These findings are of particular interest, since Chaikoff had observed (6) that in rats fed inorganic iodide the protein-bound iodine of serum also rose, though these rises were of lesser magnitudes than those described in Barker's work. Our own studies in this field (7–10), conducted in humans, indicated that oral feeding of potassium iodide in massive or even in ordinary therapeutic amounts raises the nonthyroxine fraction of the protein-bound iodine without producing hypermetabolism.

Hyperthyroidism without apparent hyper-metabolism.

A recent study in this clinic of the newer laboratory technics for appraising thyroid function 1 has revealed several points of interest. First, the evaluation of a single function of the gland, such as the ability to take up radioiodine 2 or to maintain the level of precipitable iodine in the serum, 3 does not always reflect the over-all activity of the gland. Second, the appraisal of several functions of the thyroid has not overcome this difficulty. The determination of the levels of both radioiodine tracer uptake and serum precipitable iodine chemically, or of tracer uptake and basal metabolic rate, provides, with about 95 per cent accuracy, a reflection of gland activity, but it is still not pathognomonic of either hyperthyroidism or hypothyroidism. Third, despite this limitation, the use of the newer technics has permitted the characterization of a hitherto poorly recognized group of patients who have hyperthyroidism but no

Thyroid function measured by serum precipitable iodine determinations in schizophrenic patients.

A study of the serum precipitable iodine values in 57 schizophrenic patients reveals no essential differences from the normal, although subgroup variations are suggested in the hebephrenic (high) and hyperactive (low) group. These data suggest that the hormonal output of the schizophrenic thyroid is within normal limits, and that the low basal metabolism of schizophrenics is a function not of low thyroid activity, but of defective responsivity of the schizophrenic organism to circulating thyroid hormone.

An analysis of the medical treatment of hyperthyroidism with thiourea and iodine: with special reference to the behavior of the serum precipitable iodine during therapy.

DURING the past four years thiourea together with strong solution of iodine (Lugo's solution) has been used in the prolonged medical treatment of 139 patients, with hyperthyroidism. Analysis of the usefulness of these agents in certain of these cases has already been made in preliminary reports from this department. (1, 2). For a period, all patients with hyperthyroidism of whatever nature were treated with these drugs. Since a similar group is now being treated with propyl thiouracil, for comparison, it seems pertinent to summarize the information derived from the study of patients treated for long periods with thiourea. The development of this mode of therapy with thiourea in preference to other thyroid-depressant drugs has been discussed (2). In addition to the basal metabolic rate, changes in weight and pulse rate, and other clinical manifestations of the disease, the concentration of the precipitable iodine in the serum (SPI) has been used in evaluating the condition of the patients during the course...

ALTERATIONS IN SERUM IODINE FRACTIONS INDUCED BY THE ADMINISTRATION OF INORGANIC IODIDEL IN MASSIVE DOSAGE*†

IT HAS been shown that in euthyroid adults on an intake of inorganic iodide limited to that ordinarily present in the diet the serum precipitable or protein-bound iodine remains relatively constant within the range of 4.0 to 8.0 gamma per cent (1, 2). Under these circumstances the inorganic iodide in serum also remains constant at approximately one gamma per cent (3, 4). If, however, the intake of inorganic iodide is greatly increased, the concentration of this inorganic fraction rises several hundred fold, or more (4, 5). The present study defines alterations in serum proteinbound or precipitable iodine which accompany such rises during the administration of inorganic iodide in massive doses. Materials and Methods The pertinent clinical data on 8 patients who received up to 3 grams of potassium iodide or up to 7 ml. of a saturated solution of the same salt daily during periods as long as six months are presented in the legends to Figures 2 through 9. The sera of these subjects were analyzed at intervals ...

Serum iodine fractions in subjects receiving potassium iodide in small dosage.

PREVIOUS studies from this laboratory have shown that the ingestion of an inorganic iodide in amounts as large as 3 to 7 grams per day produced a marked elevation of the total as well as the serum precipitable or protein-bound iodine (1, 2). Fractionation of the latter moiety indicated that the rise had occurred in the nonthyroxine iodine (3). Without iodide supplements, however, these various iodine fractions are known to remain relatively constant in healthy adults (4, 5). The experiments herein reported define the effects of an inorganic iodide on serum iodine fractions when administered in therapeutic amounts such as those used, for example, in hyperthyroidism. Materials and Methods Five adult male subjects received 0.2 and subsequently 0.4 gram of potassium iodide daily as a saturated aqueous solution during periods totalling approximately four to seven weeks in length. Five others were given 0.6 gram daily in the form of compressed tablets for variable periods of time. All of the subjects continued ...

Serum precipitable iodine in patients with tumors of or near the pituitary.

IN AN earlier paper (1) it was pointed out that, in a number of patients with tumors of or in the vicinity of the pituitary gland, the concentrations of precipitable iodine in the serum (SPI) were as low as they usually are in myxedema, although clinical evidences of hypothyroidism were lacking. Since that time a larger number of such patients has been studied and the investigation has been extended to include an assessment of other endocrine functions. MATERIAL AND METHOD Altogether 20 patients have been studied. With one exception they were at some time or another on the Neurosurgical Service; many were at times on the Metabolism Service of the Department of Internal Medicine. All but the last, Case 20, were examined and assessed by both services. The diagnoses were made from history, physical findings, laboratory data and x-ray examinations. In 7 cases they were verified by operation, and in 1 by postmortem examination as well.

THE CONSTANCY OF THE SERUM PRECIPITABLE OR PROTEIN-BOUND IODINE IN HEALTHY ADULTS

IT has been demonstrated that the level of serum precipitable or protein-bound iodine varies with thyroid activity (1–6). As a result of these studies it is evident that in healthy subjects without disorders of this gland the organic iodine fraction in plasma is usually somewhere between 4 and 8 gamma per cent. It is not known, however, whether or not this serum precipitable or protein-bound iodine value changes from time to time within this range in any euthyroid individual. This possibility cannot be excluded in view of the knowledge that not only the level of thyroid activity but also extra-thyroidal factors may alter the value of the organic iodine fraction in serum (7, 8). The studies herein reported establish, however, the relative constancy of the serum precipitable iodine in healthy young adults, male and female, during a period of several weeks.

ABSORPTION AND CLINICAL EFFECT OF A LARGE SINGLE DOSE OF THYROID GLOBULIN

PREVIOUS papers have described a clinical condition similar to hyperthyroidism resulting from continuous ingestion of excessive amounts of desiccated thyroid (1, 2, 3, 4, 5, 6). In the case to be reported there were no toxic effects, although a serum precipitable iodine of 40.9 gamma per cent established the fact that a great part of a single huge dose of thyroid globulin had been absorbed. REPORT OF CASE The patient, M. W., a 31-year-old married white woman, consulted her physician in the latter part of June 1947 regarding her obesity. For two years following her first parturition in 1934, when she was 18 years old, she had weighed 117 pounds. After a right salpingo-oophorectomy and appendectomy at the age of 20, and following a second pregnancy in 1938, her weight was 160 pounds. This increased after her third pregnancy in 1945 to 248 pounds. The patient's physician prescribed a low calorie diet and 3 grains of thyroid daily. During the first nine days of July 1947 the patient took a total of 27, one-gr...

TOLERANCE OF NORMAL, OF THYROIDECTOMIZED, AND OF THIOUREA OR THIOURACIL TREATED DOGS TO ORAL DESICCATED THYROID AND TO INTRAVENOUS THYROXINE1

HUMAN PATIENTS with myxedema can not take oral desiccated thyroid in amounts greater than about 0.2 gram daily without developing a supranormal level of precipitable iodine in serum along with symptoms and signs of hyperthyroidism (Winkler, Criscuolo and Lavietes, 1943; Winkler, Riggs and Man, 1945). Tolerance never develops. Euthyroid subjects, on the other hand, can often tolerate indefinitely much larger amounts of desiccated thyroid, 0.3 to 0.9 gram daily, before metabolic rate and precipitable iodine of serum increase (Riggs, Man and Winkler, 1945; Peters, Danowski and Winkler). The ingested hormone is apparently not stored by euthyroid subjects, since there is no evidence of its eventual release when thyroid medication is discontinued. A difference in response to intravenous thyrosine between myxedematous patients and euthyroid subjects has also been noted (Means, 1937; Winkler, Lavietes, Robbins and Man, 1943). As far as is known the myxedematous subject adequately treated with thyroid medication d...