In 1948, wolff and chaikoff reported that organic binding of iodide in the thyroid was decreased when plasma iodide levels were elevated acute wolff chaikoff effect, and that adaptation or escape from the acute effect occurred in approximately 2 days, in the presence of continued high plasma iodide concentrations. The wolff chaikoff effect, a temporary inhibition of thyroid hormone synthesis that supposedly occurs with increased iodine intake, is of no clinical significance. In 1948, wolff and chaikoff reported that injection of iodine in rats almost completely inhibited organification thyroglobulin iodination in the thyroid gland. Of course, no one can prove it, but scientists i respect believe this report was inspired by grants from big pharma.
Wolff chaikoff effect and cause partial inhibition of tg proteolysis. The wolffchaikoff effect, a temporary inhibition of thyroid hormone synthesis that supposedly occurs with increased iodine intake, is of no clinical significance. The large amount of iodide released during the metabolism of amiodarone leads to an adaptive blockage of further thyroidal iodide uptake and thyroid hormone biosynthesis, the socalled wolff chaikoff effect. Thyroid tumorpromoting effects of iodine deficiency and iodine excess were investigated in a rodent 2stage model to estimate an optimal iodine intake range that would not effectively promote development of thyroid neoplasia. Patients with graves hyperthyroidism are more sensitive to the inhibitory effect of pharmacologic doses of. Pdf the wolffchaikoff effect ameliorates heat stress in. We read with interest the article by johnson and rapini in a recent issue of the archives1 on transient primary hypothyroidism induced by iodine application in an elderly woman.
Direct toxic effect of the drug on thyroidal cells12. The study, that was later referred to as the wolffchaikoff wc effect says that iodine intake of. The wc effect is supposedly the inhibitory effect of peripheral inorganic iodide pii levels equal to or greater than 0. Aih is mainly due to the failure to escape from the acute wolffchaikoff effect, and, in patients with thyroid autoimmune phenomena, to concomitant hashimotos thyroiditis. These hormones can also have significant impact on kidney disease so it is important to consider the physiological association of thyroid dysfunction in relation to. Journal of enam medical college j enam med col vol 5 no 2. Escape from the acute wolffchaikoff effect is associated with a decrease in thyroid sodiumiodide symporter messenger ribonucleic. Effects of amiodarone on thyroid function annals of. In 1948, wolff and chaikoff reported that organic binding of iodide in the thyroid was decreased when plasma iodide levels were elevated acute wolffchaikoff effect, and that adaptation or escape from the acute effect occurred in approximately 2 days, in the presence of continued high plasma iodide concentrations. In a study on screening for hypothyroidism in hamburg, west germany, in a series of 91509 neonates, the determination of thyrotropin levels was done by the radioimmunologic thyrotropin neonatal dry.
Wolffchaikoff increasing doses of i increase hormone synthesis initially higher doses cause cessation of hormone formation organification. Usually, the thyroid gland escapes the wolffchaikoff effect after several weeks because autoregulatory mechanisms inhibit thyroid iodide transport, and the intrathyroidal iodine concentration consequently falls below the level required. Lugols solution had been chosen due to agranulocytosis in 9 33%, hepatotoxicity in 2 7%, other side effects in 11 41% and poor adherence to medication in 5 19%. Development of hypothyroidism induced by potassium iodide wolffchaikoff effect by madke bhushan, chikhalkar siddhi, mahajan sunanda, kharkar vidya and. The pathogenesis of aih is related to a failure to escape from the acute wolffchaikoff effect due to defects in thyroid hormonogenesis, or, in patients with positive thyroid autoantibody test, to concomitant hashimotos. Background thyroid function disorders have often been observed in preterm infants after intravenous administration of iodinated contrast medium.
The wolffchaikoff effect is the observed reduction of thyroid hormone levels due to high iodine intake. Pdf effect of excess iodine intake on thyroid on human health. Amiodarone, thyroid disorder, wolff chaikoff effect, hypothyroidism, thyrotoxicosis. Although not entirely understood, the wolffchaikoff effect is partially explained by a decrease in thyroid peroxidase. Extrathyroidal benefits of iodine journal of the american. Objective to determine whether maternal exposure to iodine or neonatal exposure to topical iodinecontaining solutions increases the risk of transient thyroid dysfunction in neonates born pdf. The study, that was later referred to as the wolff chaikoff wc effect says that iodine intake of 2 milligrams or more is excessive and potentially harmful. A second effect involves inhibition of iodine organification in the thyroid gland, thereby diminishing thyroid hormone biosynthesis, a phenomenon called the wolff chaikoff effect. The effects of varying doses of stable iodide on thyroid peroxidase function and nadphcytochrome c reductase have been studied in rats. The other side effect of iodine excess is hypothyroidism. A decrease in the expression of the sodiumiodide symporter results in reduced iodine transport, which enables the synthesis of thyroid hormone to resume. Jan wolff and israel lyon chaikoff at the university of california berkeley, is a presumed reduction in thyroid hormone levels caused by ingestion of a large amount of iodine. Sixweekold male f344 rats were given a single subcutaneous injection of 2,800 mgkg body weight nbis2hydroxypropylnitrosamine dhpn or saline vehicle.
It is known that the prolonged use of iodides can lead to hypothyroidism, termed the. Amiodaroneinduced thyroid dysfunction in clinical practice. He and his colleagues were pioneers in the use of radioactive iodine to investigate thyroid function. Population studies have determined that iodine deficiency exists in approximately 38% of the worlds population, is the leading cause of preventable mental retardation, and is of. However, it was established that sudden excess of dietary iodine can actually induce a reverse effect known as the wolff chaikoff wc phenomenon effect, in which the organification process of iodine, and hence thyroid hormone formation is instead suppressed 11, 12. Effect of excess iodine intake on thyroid diseases in. The large amount of iodide released during the metabolism of amiodarone leads to an adaptive blockage of further thyroidal iodide uptake and thyroid hormone biosynthesis, the socalled wolffchaikoff effect. This transient phenomenon, known as the wolff chaikoff effect, 33 is apparent within 24 hours. Escape from the acute wolffchaikoff effect is associated. This is referred to as the acute wolffchaikoff effect. Method thyroid function was analysed in 20 very low birthweight. It has been observed that reduced hormone levels occur with reduced thyroid iodine level. However, this inhibitory effect wolffchaikoff effect lasts only 1014 days, followed by the socalled.
Israel lyon chaikoff 2 july 1902, london, uk 25 january 1966, berkeley, california was a canadianamerican physiologist and biochemist, known for the wolffchaikoff effect. The wolffchaikoff effect and jodbasedow phenomenon describe mechanisms of thyroid autoregulation and dysregulation, respectively, during iodine excess. Iodineinduced hyperthyroidisman old clinical entity that is. It is known that the prolonged use of iodides can lead to hypothyroidism, termed the wolffchaikoff effect. Mechanism of action wolff chaikoff effect inhibition of. In a study on screening for hypothyroidism in hamburg, west germany, in a series of 91509 neonates. The wolffchaikoff effect ameliorates heat stress in rats. The developing thyroid is inordinately sensitive to the inhibitory effect of excess iodide the wolffchaikoff effect wolff and chaikoff, 1948 with the subsequent development of goiter andor hypothyroidism. Wolffchaikoff effect and cause partial inhibition of tg proteolysis. Effects of maternal iodine supplementation during pregnancy. A reduction in thyroid hormones under a high iodide concentration is called the wolffchaikoff effect. The pathogenesis of aih is related to a failure to escape from the acute wolffchaikoff effect due to defects in thyroid hormonogenesis, or, in patients with positive thyroid autoantibody test, to concomitant hashimotos thyroiditis. The developing thyroid is inordinately sensitive to the inhibitory effect of excess iodide the wolffchaikoff effect wolff and chaikoff, 1948 with the subsequent development of goiter andor hypothyroidism roti and vagenakis, 2000. Patients with graves hyperthyroidism are more sensitive to the inhibitory effect of pharmacologic doses of iodine than normal individuals.
Pdf the wolffchaikoff effect ameliorates heat stress in rats. It is proposed that iodopeptides are formed that temporarily inhibit thyroid peroxidase tpo mrna and protein synthesis and, therefore, thyroglobulin iodinations. However, in patients with toxic thyroid nodules, it is imperative that administration of a thionamide precedes that of iodide because of the potential for precipitating an iodineinduced increase in thyroid hormone production via the jodbasedow effect. The acute wolffchaikoff effect lasts for few a days and then, through the socalled escape phenomenon, the organification of intrathyroidal iodide resumes and the normal synthesis of thyroxine t 4 and triiodothyronine t 3 returns. A second effect involves inhibition of iodine organification in the thyroid gland, thereby diminishing thyroid hormone biosynthesis, a phenomenon called the wolffchaikoff effect. Tumorpromoting effects of both iodine deficiency and. Ait is due to excess iodineinduced thyroid hormone synthesis type i ait or to amiodaronerelated destructive thyroiditis type ii ait, although mixed forms often occur. Rescue preoperative treatment with lugol s solution in. The various effects of amiodarone on thyroid function. We report a case of erythema nodosum treated with potassium iodide with the development of profound hypothyroidism secondary to exogenous intake of iodide. Extrathyroidal benefits of iodine 106 journal of american physicians and surgeons volume 11 number 4 winter 2006. The wolffchaikoff effect is known as an autoregulatory phenomenon that inhibits organification in the thyroid gland, the formation of thyroid hormones inside the thyroid follicle, and the release of thyroid hormones into the bloodstream. Elemental analysis of the thyroid by laser induced breakdown.
The acute wolffchaikoff effect lasts for few a days and then. Dec 01, 2006 read wolff chaikoff effect in a newborn. Normally, thyroid hormone levels return to normal after a few days of this effect, termed the socalled escape or adaptation phenomenon. The wolff chaikoff effect is known as an autoregulatory phenomenon that inhibits organification in the thyroid glandthe formation of thyroid hormones inside the thyroid follicle, and the release of thyroid hormones into the bloodstream. Oct 26, 2017 wolffchaikoff is the effect of iodide in normal mice which lead to an increase of intrathyroidal iodine concentration within 2448 h and a subsequent decrease of thyroid hormone synthesis. In susceptible individuals amiodarone may precipitate or exacerbate preexisting organspecific autoimmunity14. Thyroid hormones play a very important role regulating metabolism, development, protein synthesis, and influencing other hormone functions. Thyroid function in very low birthweight infants after. This has been well described as the wolff chaikoff effect or phenomenon 10, 11, based on a decrease in the expression of the sodiumiodide symporter, leading to a decrease in the transport of iodide into the thyroid gland and restoration of normal thyroid function. Prevention and treatment of iodineinduced thyrotoxicosis. In 1948, wolff and chaikoff reported that organic binding of iodide in the thyroid was decreased. Amiodaroneinduced thyroid dysfunction in clinical practice s. Demands for supplemental iodine arise to attain normal thyroid function. This transient phenomenon, known as the wolffchaikoff effect, 33 is apparent within 24 hours.
Tumorpromoting effects of both iodine deficiency and iodine. Plasma inorganic iodide as a homeostatic regulator of thyroid function. Unlike thyrotoxicosis, hypothyroidism is related to a persistent wolff chaikoff effect and often has a vague presentation. Amiodarone and the thyroid dysfunction thyroid research. The effect on thyroid function depends on the dosage, but the choice of the contrast medium may be equally important, as there are appreciable pharmacological differences between them. Thyroidectomy is effective and is the only measure that consistently allows continued use of amiodarone. Williams, in comprehensive handbook of iodine, 2009. Mechanism of action wolff chaikoff effect inhibition of its own uptake into the from bps 333 at university of rhode island. Perioperative management of thyroid dysfunction marcia.
In healthy subjects there is an adaption to iodine excess by an autoregulatory mechanism within the thyroid, which serves as a defense against. This work is licensed under a creative commons attributionnoncommercial 4. It is known that the prolonged use of iodides can lead to hypothyroidism, termed the wolff chaikoff effect. Mechanism of action wolff chaikoff effect inhibition of its. However, this inhibitory effect wolff chaikoff effect lasts only 1014 days, followed by the socalled. In the context of national iodine supplementation programmes, concern has been expressed over the theoretical possibility that iodine supplementation during pregnancy might adversely affect fetal development as a result of maternal thyroid inhibition from the wolff chaikoff effect. Medical options include therapy with thionamides, perchlorate, and prednisone. However, it was established that sudden excess of dietary iodine can actually induce a reverse effect known as the wolffchaikoff wc phenomenon effect, in which the organification process of iodine, and hence thyroid hormone formation is instead suppressed 11, 12.
Wolffchaikoff effect an overview sciencedirect topics. Wolffchaikoff is the effect of iodide in normal mice which lead to an increase of intrathyroidal iodine concentration within 2448 h and a subsequent decrease of thyroid hormone synthesis. The wolffchaikoff effect is an effective means of rejecting the large quantities of iodide and therefore preventing the thyroid from synthesizing large quantities of thyroid hormones. Drugs used in the management of thyroid and parathyroid disease. Patients with autoimmune thyroid disease are more likely to develop hypothyroidism due to failure to escape from wolffchaikoff effect. Unlike thyrotoxicosis, hypothyroidism is related to a persistent wolffchaikoff effect and often has a vague presentation. Patients with autoimmune thyroiditis may fail to adapt and become hypothyroid. Wolffchaikoff effect, the synthesis of thyroid hormone is normally inhibite d. This effect is countered by the iodide leak from normal thyroid tissue. Excess iodide transiently inhibits thyroid iodide organification,a phenomenon known as the wolffchaikoff effect 8. The effects of amiodarone on thyroid function depend on underlying thyroid status and dietary iodine intake. J ybarra and colleagues1 provide no convincing evidence to support their diagnosis of amiodaroneinduced thyroiditis. This becomes evident secondary to elevated levels of circulating iodide. Markou k1, georgopoulos n, kyriazopoulou v, vagenakis ag.
The mechanism responsible for the acute wolffchaikoff effect remains elusive and has. Monitoring and effects of iodine deficiency in pregnancy. In the context of national iodine supplementation programmes, concern has been expressed over the theoretical possibility that iodine supplementation during pregnancy might adversely affect fetal development as a result of maternal thyroid inhibition from the wolffchaikoff effect. Jul 09, 2004 the acute wolff chaikoff effect lasts for few a days and then, through the socalled escape phenomenon, the organification of intrathyroidal iodide resumes and the normal synthesis of thyroxine t 4 and triiodothyronine t 3 returns. Introduction amiodarone is a type iii antiarrhythmic agent used for treatment of various arrhythmias like paroxysmal atrial fibrillation to ventricular tachycardia in patients with structural heart disease or congestive heart failure. We read with interest the article by johnson and rapini in a recent issue of the archives 1 on transient primary hypothyroidism induced by iodine application in an elderly woman. The two main hormones produced by the thyroid are triiodothyronine t3 and thyroxine t4.
In patients with multinodular goiter or latent graves disease hyperthyroidism may occur. Pdf effect of excess iodine intake on thyroid on human. But the wolffchaikoff effect does not mature until 3640 weeks gestation,2 which renders preterm infants vulnerable to the effects of iodine overload, the immediate consequences of which can be development of goitre andor transient hypothyroidism3 and neurodevelopment compromise. The presence of a faint thyroid is systematically seen in euthyroid patients chronically treated by amiodarone. Aih is mainly due to the failure to escape from the acute wolff chaikoff effect, and, in patients with thyroid autoimmune phenomena, to concomitant hashimotos thyroiditis. Escape from the acute wolffchaikoff effect is associated with a. The wolff chaikoff effect is an effective means of rejecting the large quantities of iodide and therefore preventing the thyroid from synthesizing large quantities of thyroid hormones. Function of peroxidase and nadph cytochrome c reductase. The wolffchaikoff effect ameliorates heat stress in rats animal.
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