Iodine Metabolism Research Articles

Rice OsHOL1 and OsHOL2 proteins have S-adenosyl-L-methionine-dependent methyltransferase activities toward iodide ions

Food plants are important sources of iodine, an essential nutrient required for the synthesis of thyroid hormone in humans. Understanding iodine metabolism in plants is important for tackling iodine deciency, a serious micronutrient deciency in the world. Elucidation of iodine metabolism in plants is also important for understanding biogeochemical iodine cycling because plants absorb iodine from the soil and emit considerable amounts of gaseous iodine compounds into t he atmosphere. HAMLESS TO OZONE LAYER (HOL) family proteins found in plants have been reported to synthesize methyl halides, including methyl iodide, from halide ions and S-adenosyl-L-methionine (SAM). Here, we report the kinetic analysis of two rice HOL proteins, named OsHOL1 and OsHOL2. Recombinant OsHOL1 and OsHOL2 proteins synthesized methyl iodide from an iodide ion and SAM. Kinetic analyses of the recombinant proteins showed that methyltransferase ac tivities toward iodide ions were highest among the examined substrates—bromide, chloride, and thiocyanate ions. �ese results suggested that OsHOL1 and OsHOL2 are involved in iodine metabolism in rice and contribute to methyl iodide emissions from rice.

Iodine and thyroid gland with or without nuclear catastrophe

Iodine, as a trace element, is a necessary and limiting substrate for thyroid gland hormone synthesis. It is an essential element that enables the thyroid gland to produce thyroid hormones thyroxine (T4) and triiodothyronine (T3). Synthesis of Thyroid Hormones and Iodine Metabolism. Three iodine molecules are added to make triiodothyronine, and four for thyroxine - the two key hormones produced by the thyroid gland. Iodine deficiency The proper daily amount of iodine is required for optimal thyroid function. Iodine deficiency can cause hypothyroidism, developmental brain disorders and goiter. Iodine deficiency is the single most common cause of preventable mental retardation and brain damage in the world. It also decreases child survival, causes goiters, and impairs growth and development. Iodine deficiency disorders in pregnant women cause miscarriages, stillbirths, and other complications. Children with iodine deficiency disorders can grow up stunted, apathetic, mentally retarded, and incapable of normal movements, speech or hearing. Excessive Iodine Intake. Excessive iodine intake, which can trigger a utoimmune thyroid disease and dysfunction. is on the other side. Iodine use in Case of Nuclear Catastrophe. In addition to other severe consuquences of radioactivity, high amount of radioactive iodine causes significant increase in incidence of thyroid gland carcinoma after some of the nuclear catastrophes (Hiroshima, Nagasaki, Chernobyl, Fukushima). The incidence of thyroid carcinoma was increased mostly in children. This paper was aimed at clarifying some of the possibilities of prevention according to the recommendations given by the World Health Organization.

Effects of casein on iodine metabolism in body and thyroid of mice under excessive iodine

Objective To observe the effects of casein on iodine metabolism in blood,urine and thyroid of mice under excessive iodine.Methods A 2 by 3 factorial design was used in the experiment.The levels of iodine and casein were 50 and 600 μg/L in drinking water and 0( Ⅰ ),10％( Ⅱ ),20％( m ) in food,respectively.After six and twelve months,iodine content in serum,thyroid gland and urine was determined by arsenic-cerium catalyzed spectrophotometry.Results In six months,the levels of serum iodine in 50 Ⅰ,50 Ⅱ,50Ⅲ,600 Ⅰ,600 Ⅱ,and 600Ⅲ groups were (85.59 ± 8.78),(64.59 ± 9.06),(72.53 ± 11.69),(110.04 ± 9.37),(81.06 ± 9.94),(86.63 ± 19.59)μg/L,respectively; the levels of iodine content in thyroid gland were (0.21 ± 0.09),(0.29 ±0.08),(0.24 ± 0.05),(0.50 ± 0.10),(0.37 ± 0.13),(0.42 ± 0.12)g/kg,respectively; the levels of urinary iodine median were 87.5,68.1,105.5,746.5,828.3,1014.2 μg/L,respectively.The variance analysis results of factorial design showed iodine and casein significantly influenced the serum iodine level(F =27.95,18.52,all P ＜0.05),however,there was no interaction between the two(F =0.81,P ＞ 0.05); iodine significantly influenced the iodine content in thyroid gland(F =31.35,P ＜ 0.05),the presence of iodine interacted with casein(F =3.34,P ＜0.05).In twelve months,the levels of serum iodine were (88.54 ± 12.33),(72.45 ± 7.73),(72.93 ± 13.61),( 106.26 ± 12.00),(90.03 ± 7.90),( 104.88 ± 11.67)μg/L,respectively; the levels of iodine content in thyroid gland were (0.58 ± 0.12),(0.40 ± 0.14),(0.69 ± 0.16),(0.84 ± 0.13),(0.89 ± 0.13),(1.02 ± 0.11 )g/kg,respectively;the levels of urinary iodine median were 104.8,121.5,102.7,829.1,1080.8,895.2 μg/L,respectively.The variance analysis results of factorial design showed iodine and casein significantly influenced the iodine content in serum and thyroid gland (F =42.78,7.42 and 66.62,7.90,all P ＜ 0.05),however,there was no interaction between the two(F =1.93,2.31,all P ＞ 0.05).Conclusions Long-term intake of iodine can significantly increase the iodine content in serum,thyroid gland and urine,but casein may accelerate iodine excretion and partly reduce the effect. Key words: Iodine; Caseins; Thyroid

Dietary Iodine in Pregnancy and Postpartum

Dietary iodine intake is required for thyroid hormone production. The impact of pregnancy on iodine metabolism and homeostasis and the impact of maternal dietary iodine status and supplementation on maternal thyroid volume and function are reviewed. The effects of iodine status on fetal and neonatal neurodevelopment during pregnancy and lactation are discussed.

Looking back to the future: a message for a new generation of medical educators

Many changes in medical education have occurred during the author's 50-year career in the field. The aim of this paper is to describe 10 lessons worth recording for others engaged in the training of health care professionals. The first phase in the author's career occurred during 1960-1972 in Glasgow, where an interest in medical education developed alongside an engagement in clinical medicine and research into iodine metabolism. The second phase took place during 1972-2002 in Dundee, where, after working for a period as a clinician, the author made a full-time commitment to medical education. The third phase, from 2002 to the present, has provided the opportunity to explore new horizons in medical education. The following lessons have been learned. (i) People are important as role models and collaborators. (ii) Innovation in medical education is a complex process and research findings can easily be misinterpreted. (iii) Nudges, interventions that encourage rather than mandate change, are valuable. (iv) Students are important players in planning, delivering and evaluating a curriculum. Each student has different needs and aspirations. They are the 'digital natives'. (v) Offer stakeholders practical solutions to problems that can be implemented. (vi) There is always something to learn outside one's own practice. Go to a conference or read a journal in a related field. (vii) Time spent recording one's work and publishing reports based on it is rewarding. (viii) Learn from history. We don't need to keep reinventing the wheel. (ix) Obtain independent funding. (x) Finally, and most importantly, have fun. Working in medical education can be exciting, fulfilling and hugely enjoyable.

Radioiodine tracers as useful tools in studies of thyrotoxic effects of exogenous bromide and perchlorate ions

With the use of 125I and 131I radionuclides, we followed the effects of exogenous bromide and perchlorate ions on the metabolism of iodine and of thyroid hormone in the rat. The presumed thyrotoxic effects of bromide and perchlorate have been confirmed and quantified. Correct assay conditions for the radiometric determination of the enzyme activity of thyroid peroxidase (TPO) have been established. The use of the adapted radiometric assay revealed a divergent influence of bromide and perchlorate ions on the TPO activity in the rat thyroids. Excessive bromide exerted a biphasic effect, depending on the extent of bromide intake in the animals. In contrast, in all the rats that were administered with high amounts of perchlorate were found elevated TPO activities.

Use of 82Br and 131I radionuclides in studies of goitrogenic effects of exogenous bromide

The interference of excessive bromide intake with iodine metabolism in the rat was studied using 82Br and 131I radionuclides. Mainly lactating rat dams and their pups were used, in addition to adult male rats, in the present studies. Particularly, the influence of high bromide intake in lactating rat dams on the transfer of iodine and bromide to suckling young through breast milk was evaluated. The induction of hypothyroid status in the pups by high bromide intake in the mothers was proved unambiguously. Excessive bromide in lactating rat dams caused a marked decrease in plasma levels of thyroid hormones both, in the mothers and in their sucklings. The effects of an enhanced bromide intake on the thyroid function in relation to iodine status in the animals were also followed. Marked goitrogenic and thyrotoxic effects of excessive bromide in adult rats were significantly enhanced under the conditions of simultaneous iodine deficiency in the experimental animals.

Thyroid gland and pregnancy

Thyroid gland has an important role for the functioning of the body, especially for the development of many tissues and organs during the intrauterine development. The developments in understanding of the physiology of the thyroid function in a normal pregnancy accentuated how important its disorders can be for the adverse obstetric or neonatal outcome. The normal pregnancy is characterised by major changes in thyroid economy, thyroid function tests and iodine metabolism. Therefore, normal reference ranges valid for the non-pregnant state should not be applied during gestation. In fact, the stimulatory action exerted by human chorionic gonadotropin (hCG) on the thyroid gland, with a consequent reduction of thyroid stimulating hormone (TSH) concentration, must always be taken into account when evaluating thyroid function test, especially during the first trimester of pregnancy. The right interpretation of TSH in conjunction with free thyroxine (FT4) and TSH receptor antibodies (TRAb) is of pivotal importance to distinguish not dangerous situations (gestational transient thyrotoxicosis - GTT) from health threatening ones (Graves' disease, Hashimoto thyroiditis). Graves' hyperthyroidism is associated with an increased risk of maternal and foetal complications, and an appropriate treatment with antithyroid drugs is able to abolish these adverse effects. The following are of the pivotal importance: a) the right recognition of low TSH aetyology, b) an adequate knowledge in the management of pregnant women with low TSH values.

Cardiovascular Collapse following Povidone-Iodine Wash

We present a case study of a severe episode of iodine toxicity following povidone-iodine wash with clinical manifestations of cardiovascular collapse, metabolic acidosis, renal failure and seizures. Povidone-iodine has been used as a medical antiseptic and disinfectant since 1952 Iodine toxicity secondary to povidone-iodine use is rare. Iodine toxicity is difficult to diagnose and the diagnosis is made by a high index of suspicion. Toxicity due to iodine correlates with serum and urine iodine levels. Treatment of iodine toxicity is supportive. A review of literature relating to the components of povidone-iodine, iodine metabolism, its manifestations and management of iodine toxicity secondary to povidone-iodine is also presented. An Ovid-Medline search from 1950 to 2009 revealed 1236 articles on the clinical manifestations of povidone-iodine usage but no article on iodine toxicity relating to povidone-iodine based on the following search criteria: povidone-iodine and/or iodine toxicity secondary to povidone-iodine (limited to English language, review articles, full text and human patients).

Recent advances in the nutritional ecology of the Patagonian huemul: implications for recovery

Huemul (Hippocamelus bisulcus) numbers had already declined drastically by the 1800s. Only ~500 animals remain along 1800 km of the Argentine Andes between 34 and 54°S, without cases of recolonisation or numerical responses. In Chile, at least two populations have increased; the remaining populations have either decreased or are assumed to be stable. During a Chilean–Argentine meeting in 1992 several factors were hypothesised to be important for huemul recovery (cattle, exotic trees, irrational forestry, exotic animals, illegal hunting, diseases, dogs, reduced numbers), but these can be rejected as key explanations for the general lack of recovery. Each factor may play an additive role – alone or in combination – in certain populations, but none of them are likely a primary cause. Our objective is to evaluate alternative factors and several indications warrant us to postulate that nutritional ecology instead plays a central role in the general absence of recovery. A wide range of antler quality is encountered among huemul today, with well developed specimens known primarily from historic times. If antler expression in huemul is homologous to other cervids, it follows that most extant populations are under suboptimal conditions. Another important clue is a high prevalence of age-independent osteopathy among adults. We hypothesised that such generalised secondary chronic alveolar osteomyelitis, osteoarthritis and periodontitis were hypothesised to relate to nutritional ecology. Meagre antler development with frequent asymmetry, high prevalence of osteopathy, and low recruitment rates could all be related to common and limiting nutritional factors known to cause the described phenomena. Initial investigations point to several lines of evidence that support the hypothesis that deficiency in iodine and selenium (Se) might be involved. Among other things, such deficiencies impair bone growth, reproduction, neonatal development, the immune and nervous systems, and cause periodontitis in ruminants. Se deficiency directly affects iodine metabolism. Only decades ago, overt iodine deficiency in humans living in these areas was very common. For free-ranging livestock, overt Se deficiency has been described in Chile: supported by geology, pedology, topography, and climatic patterns. It is well known that valley bottoms, flood plains, and habitats downwind from glacial areas provide higher provision of iodine and Se. The nexus to the nutritional ecology of huemul likely is the inaccessibility of most traditional winter ranges, elimination of migratory traditions, and concomitant elimination of source populations. Se and iodine provisions diminish with altitude, which at the same time increases physiological needs due to hypoxia, and intensified radiations and exercise. Most extant huemul populations occur in remote high-altitude refuges, or inaccessible Pacific coastal areas. Migration, an acquired behaviour, has been eliminated through past overhunting of this population segment; huemul being very vulnerable to human predation were killed by the thousands to feed people, dogs, chicken and pigs, and their skins were used for shelters. Huemul currently dispersing from refuges are generally being killed when entering former source areas now occupied by settlers and their dogs. Other ungulates driven into mountain refuges have been shown to be deficient in these trace minerals and responded well to mitigation of the deficiency. Thus, prevention of reaching traditional winter ranges or valley bottoms might result in inadequate mineral supply to huemul.

Iodine and pregnancy.

Iodine is a necessary element for the production of thyroid hormone. We will review the impact of dietary iodine status on thyroid function in pregnancy. We will discuss iodine metabolism, homeostasis, and nutritional recommendations for pregnancy. We will also discuss the possible effects of environmental contaminants on iodine utilization in pregnant women.

Metabolic Pathways of Tetraidothyronine and Triidothyronine Production by Thyroid Gland: A Review of Articles

Tetraidothyronine (T4) and Triiodothyronine (T3) are the two vital hormones in human metabolism produced by thyroid gland. The major pathways in thyroid hormone biosynthesis begin with iodine metabolism which occurs in three sequential steps: active iodide transport into thyroid followed by iodide oxidation and subsequent iodination of tyrosyl residues of thyroglobulin (Tg) to produce idotyrosines monoidotyrosine (MIT) and diiodothyrosine (DIT) on Tg. Oxidized iodine and tyrosyle residues which are an aromatic amino acids are integral part of T4 and T3. The thyroid iodine deficiency of either dietary, thyroid malfunction, or disorder of hypothalamus and pituitary to produce enough Thyroid Stimulating Hormone (TSH), eventually lead to hypothyroidism with sever side effects. Iodine oxidation is the initial step for thyroid hormone synthesis within thyroid, is mediated by thyroperoxidase enzyme (TPO), which itself is activated by TSH required for production of MIT and DIT. T4 and T3 are subsequently are synthesized on Tg following MIT and DIT coupling reaction. Thyroid hormones eventually produced and released into circulation through Tg pinocytosis from follicular space and subsequent lysozomal function, a process again stimulated by TSH. The production of T4 and T3 are highly regulated externally by a negative feed-back interrelation between serum T4, T3 and TSH and internally by the elevated iodine within thyroid gland. It is believed the extra iodine concentration within thyroid gland control thyroid hormones synthesis by inhibition of the TPO and hydrogen peroxide (H2O2) formation which is also an essential factor of iodine oxidation, via a complex mechanism. In healthy subjects the entire procedures of T4 and T3 synthesis re-start again following a drop in serum T4 and T3 concentration. On conditions of thyroid disorders, which caused by the distruption of either of above mechanisms, thyroid hormone deficiency and related clinical manifestations eventually begin to show themselves.

Iodine metabolism in relation to reproductive status in cows.

Summary Iodine Metabolism in Relation to Reproductive Status in Cows Studies were made on the phases of thyroid function as revealed by the determination of thyroid weight, thyroidal total and organic iodine as well as protein bound iodine and thyroid hormone potency in the sera of cows during the stages of estrous cycle, pregnancy and those affected with cystic ovaries. 1. The thyroid fresh weight was maximal in cows at proestrus and relatively increased during pregnancy. 2. The iodine concentration in the thyroid was minimal at estrus and in the cows with cystic ovaries, indicating increased depletion of thyroid hormone from the thyroid as a result of increased estrogen level in the blood. The iodine concentration in the thyroids of cows at proestrus and pregnancy were relatively high. 3. The PBI content of the thyroids was decreased in the case of cows at estrus, during pregnancy and in cows with cystic ovaries. 4. Determination of serum PBI showed a trend towards low levels in estrous cows and in those with cystic ovaries and high values reaching 12.8 micrograms per cent on average in pregnant cows. 5. The thyroid hormone potency of the sera of cows at estrus and those affected with cystic ovaries was relatively high when compared with the other stages of the cycle and during pregnancy. Zusammenfassung Beziehungen zwischen Jodstoffwechsel und Fortpflanzung Bei Kuhen wurde die Schilddrusenfunktion wahrend der verschiedenen Phasen des Brunstzyklus', wahrend der Trachtigkeit und bei Tieren mit Ovarialzysten untersucht. Ergebnisse: 1. Im Proostrum ist das Gewicht der Schilddruse am grosten. Wahrend der Graviditat erhoht sich das Schilddrusengewicht noch mehr. 2. Der Jodgehalt der Schilddruse war wahrend des Ostrums sowie bei Tieren mit Ovarialzysten am geringsten. 3. Der Gehalt an proteingebundenem Jod (PBI) nimmt bei Kuhen mit Ovarialzysten, sowie wahrend des Ostrums und der Graviditat ab. 4. Der PBI-G-ehalt ist klein wahrend der Brunst (0,86 mg%) und bei Tieren mit Ovarialzysten (0,82 mg%). Wahrend der Trachtigkeit ist der PBI-Gehalt hoch (bis 12,8 mg%). 5. Die biologische Aktivitat der Schilddrusenhormone ist wahrend des Ostrums und bei Ovarialzysten groser als wahrend der ubrigen Zyklusphasen und der Trachtigkeit. Resume Relaciones entre le metabolisme iode et la reproduction On examine la fonction thyroidienne chez des vaches, pendant les differentes phases du cycle oestral, pendant la gravidite et chez des animaux avec des kystes ovariens. Resultats: 1. C'est au cours du prooestre que le poids de la thyroide est le plus eleve. Pendant la gravidite, il s'accroit davantage encore. 2. La teneur en iode de la thyroide est la plus faible pendant l'oestre ou chez les animaux a kystes ovariens. 3. La teneur en iode lie aux proteines (PBI) diminue chez les vaches a kystes ovariens, de meme que pendant l'oestre et la gravidite. 4. La teneur en PBI est faible pendant l'oestre (0,86 mg%) et chez les animaux a kystes ovariens (0,82 mg%). Pendant la gravidite, ia teneur en PBI est elevee (jusqu'a 12,8 mg%). 5. L'activite biologique de l'hormone thyroidienne est plus grande pendant l'oestre et lors de kystes ovariens, que pendant les autres phases du cycle et la gravidite. Resumen Relaciones entre el metabolismo del iodo y la reproduccion La funcion tiroidea se examino en vacas durante las fases diversas del ciclo estral, durante la gestacion y en animales con quistes ovaricos. Resultados: 1. El peso del tiroides es maximo en el proestro. Durante la gestacion aun aumenta el peso del tiroides. 2. El contenido en iodo del tiroides era minimo durante el estro y en los animales con quistes ovaricos. 3. El contenido en iodo ligado a las proteinas (ILP) disminuye en las vacas con quistes ovaricos, durante el estro y la gestacion. 4. El contenido en ILP es escaso durante el celo (0.86 mg%) y en los animales con quistes ovaricos (0.82 mg.%). Durante la gestacion era elevado el contenido en ILP (hasta 12.8 mg.%). 5. La actividad biologica de las hormonas tiroideas es mayor durante el estro y en los quistes ovaricos que durante las fases ciclicas restantes y la gestacion.

Schilddrüsenerkrankungen und Schwangerschaft

Disorders of the thyroid in women are common during the reproductive years. Incorrect or delayed treatment during pregnancy can adversely affect the health of mother and child. Knowledge of the physiological changes during this time is essential. Thyroid disorders, in particular hypothyroidism, may compromise fertility. Autoimmune thyroiditis is associated with a higher risk of fetal loss. In women on thyroid hormone replacement therapy, the thyroxine dose has to be adjusted to meet the enhanced requirement during pregnancy. Thyroid hormone is vital to fetal brain development. During pregnancy and lactation, iodine supplementation is also recommended due to alterations in iodine metabolism. Hyperthyroidism during pregnancy can adversely affect pregnancy outcome and has to be treated accordingly. Propylthiouracil should be given using the least effective dose to keep free thyroxine levels at the upper limit of normal or slightly above. Hyperthyroidism in the fetus and the neonate can be induced by thyroid stimulating antibodies capable of passing the placenta.

Five‐Year Follow‐up of a Randomized Clinical Trial of Unilateral Thyroid Lobectomy with or Without Postoperative Levothyroxine Treatment

The aim of this study was to compare the prevalence of recurrent nodular goiter in the contralateral thyroid lobe among patients after unilateral thyroid lobectomy for unilateral multinodular goiter (MNG) receiving versus not receiving postoperative prophylactic levothyroxine (LT4) treatment. From January 2000 through December 2003, 150 consenting patients underwent a unilateral thyroid lobectomy for unilateral MNG at our institution. They were randomized to two groups with 75 patients in each group. Patients in group A received prophylactic LT4 treatment postoperatively (dose range 75-125 microg/day to maintain thyroid-stimulating hormone values below 1.0 mU/L), whereas patients in group B received no postoperative LT4 treatment. All the patients underwent ultrasonographic, cytologic, and biochemical follow-up for at least 60 months postoperatively. The primary outcome was the prevalence of recurrent goiter in the contralateral thyroid lobe. The secondary outcome was the reoperation rate for recurrent goiter. The outcomes were stratified according to individual iodine metabolism status assessed by urinary iodine excretion. During the 5-year follow-up, among patients receiving vs. not receiving LT4, recurrent goiter within the contralateral thyroid lobe was found in 1.4% vs. 16.7% of patients, respectively (p = 0.001). Moreover, 1.4% vs. 8.3%, respectively, of patients receiving vs. not receiving LT4 required contralateral thyroid lobe surgery (p = 0.05). LT4 decreased the recurrence rate among iodine-deficient patients (3.4% vs. 36%, respectively; p = 0.002) but not among iodine-sufficient patients (0% vs. 6.4%, respectively; p = 0.09). Prophylactic LT4 treatment significantly decreased the recurrence rate of nodular goiter in the contralateral thyroid lobe and the need for completion thyroidectomy, mostly among patients with iodine deficiency.

Chirurgie der Schilddrüsenkarzinome

The 5 main types of thyroid cancer (papillary, PTC, follicular, FTC, poorly differentiated, PDTC undifferentiated, UTC, medullary, MTC) not only differ regarding morphology, pathogenesis, genetics,and pathophysiology (iodine metabolism, thyroglobulin and calcitonin production), but also concerning tumor biology, metastatic behavior (lymphogenous, locally invasive and hematogenous routes) and prognosis. Knowledge of these features is the basis of the surgical concept of one or two-stage thyroidectomy, the exceptions and the concept of locoregional lymph node dissection. Lymph node surgery plays an important role in those cancers exhibiting mainly lymph node metastases (PTC, MTC) not only due to frequent recurrences but also due to its potential curative intent. Differentiated carcinomas may have an acceptable prognosis despite local invasion of the cervical aerodigestive system, thus resections are justified when technical prerequisites are given.

Kinetics of acute and chronic iodine excess.

Iodine plays an important role in thyroid physiology resulting from its importance as a requisite substrate for the synthesis of thyroid hormones and from its action as a regulator of thyroid function. Following intestinal absorption, inorganic iodide is largely confined to the extracellular fluid. Serum concentrations of inorganic iodide well reflect the amount of iodine present in the extracellular compartment. Since serum inorganic iodide levels are important determinants of thyroid iodine uptake, serum iodide measurement offers a valuable tool for the investigation of many basic and clinical aspects of thyroid iodine metabolism. Here we summarize important aspects of iodine metabolism and focus selectively on technical aspects of serum inorganic iodide measurement and on the kinetics of inorganic iodide in various states of iodine excess. Presently, paired-ion, reversed-phase HPLC with electrochemical detection is obviously the best method for measurement of serum inorganic iodide being highly sensitive, easy to perform, and almost completely insensitive to interfering substances. Using this method, we could demonstrate an acute increase of serum inorganic iodide during the administration of large amounts of iodide as Lugol's solution given preoperatively in patients with Graves' hyperthyroidism. In patients under treatment with the iodine containing drug amiodarone (n=37), serum inorganic iodide levels were highly elevated (range 3.5-208.2 microg/dl, median 36.6 microg/dl). Serum concentrations of inorganic iodide were correlated neither to the daily amiodarone dose, nor to the serum levels of amiodarone.

Appropriate Time for Post-Therapeutic I-131 Whole Body Scan

Iodine metabolism and kinetics in thyroid carcinoma cells may be different from that in normal thyroid tissue. The optimal time for performing post-therapeutic scans to detect metastatic lesions is still controversial.We retrospectively analyzed the images of 239 patients who received I-131 therapy at our hospital from January 2006 to May 2008. The therapeutic dose ranged from 1.1 GBq (30 mCi) to 7.4 GBq (200 mCi) and the patients received 3 sequential whole body scans on the third to fourth day, fifth to sixth day, and 10th-11th day after I-131 administration. We scored the I-131 avid lesions by visual assessment into 3 grades: 2=clearly visible; 1=visible; and 0=not visible. We also compared the thyroglobulin levels and FDG uptake among the lesions with probably different kinetics of iodine metabolism.In this study, there was a trend of decreasing visualization of lesions in the sequential images. Twenty-eight percent of lymph node metastases, 17% of lung metastases, and 16% of bone metastases were missed on the late images on 10-11th day. On the other hand, only 5% of the remnants were missed. The ratio of early washout was different between remnants and metastatic lesions. The serum thyroglobulin levels and FDG uptake did not correlate with early washout of the I-131 avid lesions. We concluded that earlier imaging is necessary for detection of metastatic lesions.

Breastfeeding and maternal and infant iodine nutrition

The aim of this review is to explore information available regarding iodine secretion in milk, both mothers and infants iodine nutrition during breastfeeding and to make recommendations for appropriate iodine supplementation during lactation. MEDLINE was queried for studies between 1960 and 2007 that included lactation and breastfeeding with iodine and iodine deficiency. Studies were selected if they studied (i) Secretion of iodine in breast milk; (ii) breastfeeding and iodine nutrition; (iii) factors affecting maternal iodine metabolism and (iv) recommendations for iodine supplementation during breastfeeding. Thirty-six articles met the selection criteria. The iodine content of breast milk varies with dietary iodine intake, being lowest in areas of iodine deficiency with high prevalence of goitre. Milk iodine levels are correspondingly higher when programs of iodine prophylaxis such as salt iodization or administration of iodized oil have been introduced. The small iodine pool of the neonatal thyroid turns over very rapidly and is highly sensitive to variations in dietary iodine intake. Expression of the sodium iodide symporter is up-regulated in the lactating mammary gland which results in preferential uptake of iodide. In areas of iodine sufficiency breast milk iodine concentration should be in the range of 100-150 microg/dl. Studies from France, Germany, Belgium, Sweden, Spain, Italy, Denmark, Thailand and Zaire have shown breast milk concentrations of < 100 microg/l. Adequate levels of iodine in breast milk have been reported from Iran, China, USA and some parts of Europe. Adequate concentration of iodine in breast milk is essential to provide for optimal neonatal thyroid hormone stores and to prevent impaired neurological development in breast-fed neonates. In many countries of the world, low iodine content of the breast milk indicates less than optimum maternal and infant iodine nutrition. The current WHO/ICCIDD/UNICEF recommendation for daily iodine intake (250 microg for lactating mothers) has been selected to ensure that iodine deficiency dose not occur in the postpartum period and that the iodine content of the milk is sufficient for the infant's iodine requirement.

Expression of iodine metabolism genes in human thyroid tissues: evidence for age and BRAFV600E mutation dependency

Children present a higher susceptibility to developing thyroid cancer after radioiodine exposure and also a higher frequency of functional metastases than adults. To assess the mRNA expression of the sodium/iodide (Na(+)/I(-)) symporter (NIS), the Pendred syndrome gene (PDS), thyroperoxidase (TPO), thyroglobulin (Tg) and TSH receptor (TSH-R) in normal thyroid tissues (NTTs) and papillary thyroid carcinomas (PTCs) among different age groups. Analysis included 59 samples: 21 NTTs and 38 PTCs, of which 21 were the classic type (CPTC) and 17 the follicular variant (FVPTC). Patients were divided into three age groups: I (n = 16) 5-21 years, II (n = 13) 22-59 years, and III (n = 10) 60-91 years. The relative mRNA expression of the five target genes was determinate by quantitative reverse transcription polymerase chain reaction (QRT-PCR). Expression of all genes was significantly higher in NTTs than in PTCs, and it was not age dependent in the NTT group. Among PTCs, the mean expression of PDS, TPO and TSH-R was significantly lower in group II than in group I. PDS, TPO and Tg expression was significantly lower in classic PTCs than in FVPTCs. The difference was related to a higher frequency of the BRAF(V600E) mutation in the former group. The finding of higher PDS, TPO and TSH-R mRNA expression in paediatric vs. adult primary tumour tissues supports the hypothesis that this might contribute to the increased functional activity of metastases in the paediatric group. The finding that mRNA expression of the target genes in NTT was not age dependent does not provide an explanation for the higher susceptibility in the paediatric group.