Serum Iodide Concentration Research Articles

The joint role of thyroid function and iodine concentration on gestational diabetes risk in a population-based study.

Iodine is essential for thyroid function, and iodine deficiency during pregnancy is common in Europe and the USA. However, no published studies have examined the role of iodine deficiency in the relation between thyroid function and gestational diabetes mellitus (GDM). We conducted a population-based, nested case-control study within the Finnish Maternity Cohort using pregnancy and perinatal outcome data from the Finnish Maternal Birth Register. We randomly selected 224 GDM cases with singleton pregnancies and 224 controls without GDM from all singleton births occurring in Finland during 2012-2013. Blood was drawn at 10-14weeks' gestation and analyzed for serum iodide, thyroglobulin, and thyroid-stimulating hormone (TSH) concentrations. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) of GDM. Very high thyroglobulin concentration (>95% percentile; >83μg/L) was not associated with significantly altered odds of GDM compared to those with normal levels (OR 0.41; 95% CI: 0.12, 1.38). High concentrations of TSH were also not associated with increased odds of GDM compared to normal levels of TSH (OR 0.45; 95% CI: 0.06, 3.18). Women in the lowest 5th percentile (<1.58ng/mL) of iodine did not have increased odds of GDM compared to those with iodide in the highest quartile (OR 0.39; 95% CI: 0.11, 1.35). Low levels of iodide and thyroid function in early pregnancy are not associated with increased risk of GDM in this mildly iodine-deficient population.

Contrast nephropathy with a non-ionic iodide medium in patients with normal and mildly impaired renal function

Effects of infusion of a non-ionic contrast medium(iopamidol, 370 mg l/ml) on renal function in a normovolemic state were examined in patients with normal and mildly affected renal function who underwent coronary angiography(CAG). The patients were divided into three groups: group I (n = 69) with serum creatinine(S-Cr) level < 1.0 mg/dl; group II (n = 50) with S-Cr level of 1.0 to 1.3 mg/dl and group III(n = 17) with S-Cr level of 1.3 to 2.0 mg/dl. Patients with S-Cr > or = 2.0 mg/dl were subjected to 3-h hemodialysis immediately after CAG(group HD, n = 11). Serum(S) and urine(U) values of Cr, Na, K, Cl, beta 2-microglobulin(beta 2MG), and U-N-acetyl-beta-D-glucosaminidase(NAG) were measured before and 24 h after CAG. U-NAG and U-beta 2MG were corrected for U-Cr, and fractional excretion of beta 2MG(FE beta 2MG) was determined. Basal U-NAG/Cr, U-beta 2MG/Cr and FE beta 2MG were increased in groups III and HD, suggesting the preexistence of tubular dysfunction. S-Cr was increased significantly only in group I, but there was no change in S-beta 2MG. U-NAG/Cr after CAG was elevated in all the groups, whereas U-beta 2MG/Cr(or FE beta 2MG) was increased only in group III. Greater than two-fold increases of U-NAG/Cr were noted equally in groups I through III. In contrast, the greater than two-fold increase of U-beta 2MG/Cr(or FE beta 2MG) occurred more frequently in group III as compared to the other groups. The incidences of such cases in group HD were similar to those of group III. The half life of serum iodide concentration was significantly shortened by 3-h HD(1.8 +/- 0.3 h vs. 15.9 +/- 3.8 h without HD). In conclusion, patients presenting S-Cr > or = 1.3 mg/dl were at high risk of renal tubular dysfunction even when contrast media was administered in the absence of significant increase in S-Cr. Whether an increase in U-NAG/Cr indicates tubular damage or is merely the result of tubular reabsorption of the agent remains to be clarified. Post-CAG hemodialysis efficiently eliminates contrast medium from the circulation.

Circulating iodide concentrations during and after pregnancy.

Early, indirect studies suggested that an important aspect of thyroid economy during pregnancy was a decline in plasma or serum inorganic iodide (PII) concentrations, but there is little information concerning circulating iodide concentrations as assessed by direct measurement. The present study was undertaken to determine the relationship between gestation and serum iodide concentrations as assessed by direct measurement of PII. PII concentrations, urinary iodide levels, and other parameters of thyroid economy were measured during the first, second, and third trimesters and after delivery in 16 women. Mean serum T4 concentrations were significantly higher in all 3 trimesters than those after delivery. Serum free T4 index concentrations were significantly higher in the first trimester than during later periods of gestation or after delivery, but serum TSH concentrations were not depressed in the first trimester. Serum thyroglobulin concentrations were similar during pregnancy and after delivery. There was wide variability in PII and urinary iodide concentrations during and after pregnancy, but there was no trend for PII concentrations to be depressed during pregnancy. Pregnancy, at least in iodine-sufficient regions, does not have an important influence on circulating concentrations of iodide.

Iodide‐induced hypothyroidism in patients after thyroid resection

The purpose of this investigation was to determine whether an intrinsic defect in thyroid hormone production is required for the development of iodide-induced hypothyroidism or does it also develop in TSH-stimulated normal thyroid tissue. To answer this question, we studied the response to iodine administration (180 mg iodide daily for 3-4 months) in eight euthyroid patients who had had partial thyroidectomies 2 months to 10 years previously for benign thyroid nodules, and in three euthyroid control subjects. In all 11 euthyroid patients, basal serum TSH concentrations increased during iodide administration. In six of the eight patients who had previous thyroid operations and in two of the three control patients, basal serum TSH concentrations increased into the abnormal range (greater than 6 U ml-1). Increased serum TSH concentrations were noted as early as 1 week after potassium iodide had been started and the increased levels persisted during the period of iodide administration. Although basal values for serum TSH concentration were initially within the normal range, those patients with highest basal serum TSH values developed the greatest increase in TSH in response to potassium iodine. Among the eight patients treated by partial thyroidectomy, serum T4 concentrations decreased in five, serum T3 concentration decreased in three and all five developed mild symptoms of hypothyroidism while receiving iodide. Serum T4 concentrations also decreased slightly in two of the three control patients. Serum total iodine levels increased from 7.0 +/- 0.5 to 315.7 +/- 108.6 g dl-1 (mean-+/- standard error) during potassium iodide administration, but there was no correlation between the level of serum iodide concentration achieved and inhibition of thyroid function.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of topical povidone I solution on serum iodide levels and thyroid uptake of 131I in dogs.

Topical application of povidone I solution in dogs has been found to be effective in producing significant elevations in serum iodide concentrations within 2 h after application. Among dogs treated with this preparation 2 h before oral administration of 131I, significant thyroid blocking persisted for at least 72 h.

Effects of oral erythrosine (2′,4′,5′,7′-tetraiodofluorescein) on thyroid function in normal men

Erythrosine (Er), a tetraiodinated derivative of fluorescein, is a coloring agent widely used in foods, cosmetics, and pharmaceutical products. Because of its high iodine content and previous reports demonstrating an inhibitory effect of eythrosine on hepatic 5′-monodeiodination, we studied the effects of this compound on thyroid function and serum and urinary iodide concentrations in normal subjects. Thirty normal men, equally divided into three treatment groups, each received a 14-day course of oral Er in doses of 20, 60, or 200 mg/day. Serum thyroxine (T4), triiodothyronine (T3), reverse T3 (rT3), thyroid stimulating hormone (TSH), protein-bound iodide (PBI), and total iodide concentrations, serum T3-charcoal uptake, and 24-hour urinary iodide excretion were measured on Days 1, 8, and 15. Thyrotropin-releasing hormone (TRH) tests were performed on Days 1 and 15. There were no significant changes in serum T4, T3, rT3, and T3-charcoal uptake values at any dose. In men receiving 200 mg Er/day, the mean basal serum TSH concentration increased significantly from 1.7 ± 0.1 (SE) on Day 1 to 2.2 ± 0.1 μU/ml on Day 15 ( p < 0.05), and the mean peak TSH increment after TRH increased from 6.3 ± 0.5 to 10.5 ± 1.0 μU/ml ( p < 0.05). There were no significant changes in basal or peak TSH responses in the men receiving 20 or 60 mg Er/day. Significant dose-related increases in serum total iodide and PBI concentrations occurred during all three doses, and significant dose-related increases in urinary iodide excretion occurred during the 60 and 200 mg/day Er doses. These data suggest that the increase in TSH secretion induced by Er was related to the antithyroid effect of increased serum iodide concentrations, rather than a direct effect of Er on thyroid hormone secretion or peripheral metabolism.

Effect of variations in acute and chronic iodine intake on the accumulation and metabolism of [ 35S]propylthiouracil by the rat thyroid gland

Studies were performed to ascertain the effect of varying levels of chronic iodine intake and varying doses of iodide [0.002–100 μmoles KI/100 g body weight (BW)] given acutely on the rat thyroid metabolism of [ 35S]PTU (8.76 μmoles/kg BW). With variations in both acute and chronic iodine intake, as much as four-fold changes in the thyroid content of total 35S and unchanged [ 35S]PTU were observed. In the low, normal and high chronic iodine intake groups increasing doses of iodide given acutely produced a biphasic response in the thyroid accumulation of total 35S and unchanged [ 35S]PTU. In each of the three chronic iodine intake groups, increasing iodide doses up to 0.1 μmoles/100 g BW were associated with an increase in total 35S and unchanged [ 35S]PTU. At this level of acute iodide dosage, the increase averaged 45% (P < 0.01). Following acute iodide doses greater than 0.1 and up to 5.0 μmoles/100 g BW, the mean total 35S and unchanged [ 35S]PTU decreased to levels significantly (P < 0.001) lower than those at the peaks. Greater doses of iodide (up to 100 μmoles/100 g BW) produced no consistent further change in the thyroid content of total 35S or unchanged [ 35S]PTU. Irrespective of the acute iodide dose, the higher the level of chronic iodide intake, the higher the thyroid accumulation of total 35S and the lower the overall mean percentage of total 35S present as unchanged [ 35S]PTU. As would have been expected, increasing acute doses of iodide were associated with progressive decreases in thyroid: serum iodide concentration gradients, and the dose of acute iodide required to induce an acute Wolff-Chaikoff effect was greater the higher the level of chronic iodine intake. No correlation was evident, however, between the effects of acute doses of iodide on aspects of intrathyroid iodine metabolism and their effect on the thyroid metabolism of [ 35S]PTU.

Thyroid dysfunction in uremia: evidence for thyroid and hypophyseal abnormalities.

Disturbances in thyroid function and a high prevalence of goiter develop in patients on chronic hemodialysis. This study shows that in patients on dialysis, mean serum thyroxine and triiodothyronine levels are lower than normal. Patients with chronic renal failure not on dialysis, have mean serum thyroxine levels similar to normal subjects and low mean serum triiodothyronine levels. However, both serum thyroxine and triiodothyronine concentrations decrease as the renal failure worsens. In addition, both groups of patients with renal failure have a decreased serum thyroxine response to oxogenous thyrotrophin and a diminished serum thyrotrophin response to thyrotrophin-releasing hormone. These data suggest the presence of an intrathyroidal and an hypophyseal defect in uremic patients. Although serum iodide concentrations are elevated, there is no correlation between the level of serum iodide and the degree of renal failure. Therefore, we have no direct evidence that iodide excess is responsible for the abnormalities observed.

Removal of iodinated contrast material by peritoneal dialysis.

Acute renal failure following administration of radiographic contrast material is being reported with increasing frequency. In this study the clearance and extraction of iodinated contrast material by peritoneal dialysis was determined in a patient who became anuric following drip infusion pyelography. During 64 h of dialysis the serum iodide concentration decreased by a factor of 10, the peritoneal clearance of iodide was 12.1 ml/min, and 56% of the administered iodide was removed. These results suggest that contrast materials can be removed by dialysis if nephrotoxicity develops.

Seasonal changes in the extrathyroidal distribution of iodide in the teleost fish the burbot, Lota lota L.

The distribution of radioactivity in tissues of adult burbot weighing 1 to 3 kg was determined by measuring the T/S ratio (tissue radioactivity/serum radioactivity) at intervals after the injection of radioiodide. In one instance the skin which comprises 12% of body weight of the burbot showed a T/S ratio of 29.3 and accounted for up to 27% of the injected dose of radioiodide. By comparison, in another study, the thyroid showed a T/S ratio of 5.2, representing 2.2% of the injected dose at 9.5C. The radioactivity (T/S ratio) in the skin increased until 30 h after injection and then declined.Non-radioactive iodide values of skin and serum were determined on a natural population over the course of a year. Values for skin iodide ranged from 227 μg/100 g to 816 μg/100 g while serum iodide values ranged from 7 μg/100 ml to 30 μg/100 ml. These values also indicate the magnitude of seasonal variation, which, in the case of serum iodide concentration, parallels the seasonal changes in lake temperature.

The iodide space in rabbit brain.

1. The iodide space in rabbit brain varies greatly depending on the conditions under which it is determined.2. When (131)I(-) only is used the iodide space 4 hr after administration of the marker is of the order of 2%. The iodide content of the cerebrospinal fluid (c.s.f.) is about 1% of that of the serum.3. Depression of the active iodide transport by perchlorate increases the space to 8.2% and the iodide content of the c.s.f. to 26% of that of the serum.4. The active iodide transport can also be depressed by saturation with unlabelled iodide. Up to a serum iodide concentration of 5 mM the space determined after 5 hr remained constant at 2.7%. The iodide space grew when the serum iodide content was enhanced from 5 to 20 mM, to become constant at a value of 10.6% on further increase of the serum iodide (up to 50 mM). The iodide content of the c.s.f. increased in a similar manner as the space with the iodide concentration of the serum to about 1/3 of the serum concentration. The iodide space of the muscle was independent of the plasma iodide content.5. From 4 to 8 hr after administration of (131)I(-) alone or with unlabelled iodide (to a serum concentration of 15 mM) the iodide space remained relatively constant.6. When (131)I(-) was administered in the fluid with which the ventricles were perfused an iodide space of about 7% was attained after about 5 hr.7. In experiments in which (131)I(-) was administered intravenously and the sink action of the c.s.f. was eliminated by perfusion of the ventricles with a perfusate containing as much (131)I(-) as the plasma, the iodide space was 10.2%. When in addition active iodide transport was depressed by perchlorate the space increased to 16.8%.8. Intravenous administration of labelled and unlabelled iodide (to a serum concentration of 20-40 mM) and ventricle perfusion with the same concentration of (131)I(-) and unlabelled iodide as in the plasma yielded an iodide space of 20.8%. In similar experiments the iodide concentration of the perfusate was so adjusted that after 5 hr perfusion its iodide content hardly changed during the passage through the ventricles. Under these conditions the iodide concentration of the extracellular and perfusion fluids can be considered to be near equal. The iodide space computed on the basis of the iodide content of the outflowing fluid was 22.5%.9. The large iodide space could be equated with the extracellular space if the iodide remained extracellular. This seems to be the case in the muscle where the iodide space is similar to the inulin space.10. The large effects on the iodide space of perchlorate and saturation with unlabelled iodide in experiments in which the marker was administered intravenously and in the perfusate (7 and 8) suggests the presence of an active iodide transport from the brain extracellular fluid into the blood over the blood-brain barrier.

Inhibition of organic binding of iodine with graded doses of iodine in euthyroid men.

ABSTRACT The inhibition of thyroidal organic binding of iodine by iodide (Wolff-Chaikoff effect) was studied in 15 euthyroid men. The subjects received 5 U thyrotropin im for 3 consecutive days and varying doses of iodide for 48 hr before measuring the thyroid uptake of 132I. After the determination of the 3 hr thyroid 132I uptake, serum iodide, and thyroid iodide uptake, 1 g potassium perchlorate was given orally and thyroid 132I was measured 1 hr later. A positive response indicative of inhibition of organic binding was defined as a loss of 15% 132I in the thyroid at 3 hr. The base line thyroid uptake (5.00 ± 0.96%) and thyroid iodide uptake (4.48 ± 0.53 μg/hr) increased 3-fold with the administration of thyrotropin. As iodide intake increased, the serum iodide increased, the thyroid 132I uptake fell, but the thyroid iodide uptake increased progressively. A positive perchlorate response occurred in 11 subjects at iodide doses ranging from 1 to 16 mg daily, serum iodide concentrations of 2.5 to 36.9 μg/1...

HORMONE SYNTHESIS BY A TRANSPLANTABLE THYROID TUMOR IN MICE.

A spontaneous thyroid adenoma found in a hybrid mouse of C3Hf and I strains was successfully transplanted for 28 passages into mice of similar breeding history. The tumor showed autonomy in growth and its histology resembled that of a microfollicular adenoma. It frequently grew to 300–400 mg in size 2 months after inoculation, without signs of metastasis. It concentrated iodide to about twice the serum iodide concentration, if organic binding of radioiodine was blocked by propylthiouracil. When organic binding was allowed to take place, the total I131 uptake of tumor often reached 30 % of the given dose within 6 hr. Approximately 95% of this accumulated radioactivity was found in the protein fraction precipitable by trichloroacetic acid. Upon hydrolysis, the tumor homogenate yielded the I131 label in the following distribution: monoidotyrosine (50–60%), diiodotyrosine (17–20%), 3,5,3′-triiodothyronine (trace-5%) and thyroxine (trace-11%). Under similar conditions, normal mouse thyroid yielded I131 as mono...

Factors Affecting the Secretion of Iodine131 into Milk of Lactating Goats

Summary Radioactive iodine (I 181 ) was injected into eight lactating goats and its relative concentration in the iodide and protein-bound iodine (PBI) fractions of milk and blood serum was compared. About 92% of the I 131 in milk occurred as iodide and the remainder was found in the PBI fraction. During 70 hr. following I 131 injection the iodide concentration in milk of control animals was more than ten times that in blood serum, indicating an active process in mammary tissue for the secretion of iodide. Milk: serum iodide concentration was not affected by administration of 5.0g. thiouracil or 50.0mg. of nonradioactive KI daily. The concentration gradient was abolished, however, by injecting 1.0g. daily of KSCN. None of the drug treatments had a discernible effect on the PBI fraction of milk. Excluding values for the thiocyanate group (where milk iodide secretion was blocked), a 0.795 correlation (P = 0.07) was found between milk iodide: serum iodide ratio and daily milk yield. In a preliminary experiment, this correlation was 0.913 (P = 0.01). Thus, it is pointed out that in high-producing animals total iodide secretion into milk is increased not only because of the greater volume of milk produced but also because of the higher iodide concentration gradient maintained in highly active mammary tissue. This loss of iodide in milk could indirectly become a limiting factor on milk production by reducing the amount of iodide available for the formation of thyroid hormone.

Serum concentration and thyroidal uptake rate of stable iodide in various states of thyroid function.

ABSTRACT The thyroidal uptake rate of stable iodide is equal to the product of the thyroidal clearance rate of iodide and the serum concentration of stable iodide. A new method is reported for the determination of serum iodide concentration from the specific activity of saliva iodine. The determined values of serum iodide concentration are smaller than those reported by others, but there was no significant difference in a series of 16 patients with various states of thyroid function. Daily hormone formation and release may be calculated from the thyroidal uptake rate of stable iodide. By comparison of the quantitative results of iodide metabolism with the clinical state, evaluation of effective thyroid function may be possible under various clinical or experimental conditions. The thyroidal radioiodide accumulation rate is a function of the thyroidal clearance rate of iodide, i.e., the capacity of the total gland to accumulate iodide. However, neither of these rates reflects the actual uptake rate of stab...

Acute effect of organic binding of iodine on the iodide concentrating mechanism of the thyroid gland.

The organic binding of radioiodine by the thyroid gland of the mouse was blocked within 1 minute by the intravenous injection of 1 mg of propylthiouracil (PTU). In mice fed a very low iodine diet the ratio of the radioiodide concentration in the thyroid gland to that in the serum (T/S) was reduced significantly by injection of 1.5 µg of iodide 15 minutes before intravenous PTU injection. The amount of iodine bound prior to PTU injection was only a small percentage of the total iodine in the thyroid gland. This reduction did not occur in mice with less active thyroid glands. However, in the latter mice, doses of 22.5 µg of iodide or more injected 90 minutes before PTU caused a small but systematic decrease in the T/S when compared at fixed serum iodide concentration with mice given PTU before the iodide. In addition, in these mice given both PTU and iodide the T/S was greater than in mice given iodide but no PTU. It is concluded that the organic binding of iodine causes a decrease in the T/S in mice with active thyroid glands. In addition, PTU increases the T/S in mice in which organic binding of iodine is blocked by iodide.

Nature of the inhibition by thiocyanate of the iodide concentrating mechanism of the thyroid gland.

The dependence of the ratio of the radioiodide concentrations in thyroid gland and serum ( T/S) on the serum iodide concentration for fixed serum thiocyanate concentrations was investigated in C3H mice. The empirical equation (See PDF for Equation) where [SCN–] and [I–] are the serum thiocyanate and iodide concentrations in mg %, fitted the data within the limits of experimental error. Interpretation of the empirical equation was based on simple adsorption and active transport models of the iodide concentrating mechanism. The inhibition by thiocyanate of the thyroidal iodide concentrating mechanism appears to be competitive.

Dependence of ratio of radioiodine concentrations in thyroid gland and serum on serum iodide concentration: with propylthiouracil.

ASTUDY of the dependence of the ratio of the thyroid radioiodide concentration to the serum radioiodide concentration (T/S ratio) on the serum iodide concentration has been reported in the rat by Halmi (1954). This paper reports a similar study in normal and hypophysectomized mice. In addition, using simple models, formulae have been derived describing the dependence of the T/S ratio on the serum iodide concentration and predictions of the formulae are compared with the appropriate experimental results in both mice and rats. MATERIALS AND METHODS Male C3H mice were used. The normal mice were four months of age at the time of the radioiodine study. The hypophysectomized mice were fourteen weeks old at the time of the operation which was done eight days before the radioiodine study. They were hypophysectomized through the parapharyngeal approach. Completeness of the operation was ascertained by visual inspection of the region of the sella turcica for pituitaiy fragments using a binocular microscope at 9 × m...

Dependence of ratio of radioiodide concentrations in thyroid gland and serum on serum iodide concentration: without propylthiouracil.

THE ratio of the thyroid radioiodide concentration to the serum radioiodide concentration (T/S ratio) was less when organic binding of iodine by the thyroid gland was permitted, than when binding was blocked by propylthiouracil (Wollman and Scow, 1953). Since a sufficiently high concentration of serum iodide is known to block binding of iodine in the rat (Wolff and Chaikoff, 1948), it might be expected to block thyroid binding of iodide in the mouse and thereby elevate the T/S ratio in the mouse. This paper presents data describing the dependence of the T/S ratio on the serum iodide concentration in mice. The preceding paper (Wollman and Scow, 1954) described a similar study with the exception that the mice were given a single dose of propylthiouracil to block binding. A comparison is made of the T/S ratio when binding is blocked by iodide with that when binding is blocked by both prop3dthiouracil and iodide. METHODS AND MATERIALS Male C3H mice, four months of age, were used.

A study of various influences on the iodide concentrating mechanism of the rat thyroid.

THE concentration (“trapping”) of iodide by the thyroid is one of the most specific functions of this gland and constitutes the first step in thyroid hormone biogenesis. If the subsequent organic binding of iodine is blocked with thiouracil, the thyroid: serum iodide concentration ratio (T/S) can be determined (Vanderlaan and Vanderlaan, 1947). These authors found the T/S of normal rats to be around 25:1. The following findings indicated that the thyroidal iodide trap is profoundly influenced by thyrotrophin (TSH): a) In rats made goitrous by the chronic administration of propylthiouracil (PTU) the T/S rose to an average value of 250:1 (Vanderlaan and Vanderlaan, 1947); b) After hypophysectomy PTU did not have such an effect and the T/S of hypophysectomized, PTU treated rats was found to be around 6:1 (Greer, 1949); c) A single dose of TSH, given to normal rats, caused a transient rise in the T/S (Vanderlaan and Greer, 1950).