scholarly journals Increased prevalence of hyperthyroidism as an early and transient side-effect of implementing iodine prophylaxis

2007 ◽  
Vol 10 (8) ◽  
pp. 799-802 ◽  
Author(s):  
Filip Gołkowski ◽  
Monika Buziak-Bereza ◽  
Małgorzata Trofimiuk ◽  
Agata Bałdys-Waligórska ◽  
Zbigniew Szybiński ◽  
...  

AbstractObjectiveTo assess the prevalence of hyperthyroidism just after implementation of iodine prophylaxis among adults from an area with iodine deficiency.Study design and subjectsA total of 1648 adults (age 16 years and older) were sampled from an area of southern Poland during two nationwide epidemiological surveys. Of these, 1424 adults with negative medical history for thyroid disorders qualified for final analysis. The authors compared thyroid dysfunction in participants prior to (1989–1990) and after implementation of iodine prophylaxis (1997–1999).SettingThe southern part of Poland.ResultsWe found an increase in the serum concentration of anti-thyroid microsomal antibodies from 4.9% in the years 1989–1990 to 12.1% after introduction of iodised household salt (P < 0.0001). The prevalence of hyperthyroidism (defined as thyroid-stimulating hormone < 0.4 μU ml− 1) significantly increased in the equivalent period from 4.8 to 6.5% (P = 0.009).ConclusionsWe concluded that a sudden rise in iodine intake after implementation of iodine prophylaxis among adults from the area with iodine deficiency may lead to an increase in thyroid autoimmunity and prevalence of hyperthyroidism. Those possible early side-effects appear to be only temporary and are acceptable when compared with the evident benefits of adequate iodine intake.

Author(s):  
Claudia Teti ◽  
Marta Panciroli ◽  
Elena Nazzari ◽  
Giampaola Pesce ◽  
Stefano Mariotti ◽  
...  

AbstractAdequate iodine intake is necessary for normal thyroid function. Iodine deficiency is associated with serious complications, but also iodine excess can lead to thyroid dysfunction, and iodine supplementation aimed to prevent iodine deficiency disorders has been associated with development of thyroid autoimmunity. The epidemiology of thyroid diseases has undergone profound changes since the implementation of iodoprophylaxis, notably by means of iodine-enriched salt, specifically resulting in decreased prevalence of goiter and neonatal hypothyroidism, improved cognitive function development in infancy, and reduced incidence of more aggressive forms of thyroid cancer. The main question we address with this review is the clinical relevance of the possible effect on autoimmunity exerted by the use of iodine-enriched salt to correct iodine deficiency. In animal models, exogenous iodine is able to trigger or exacerbate thyroid autoimmunity, but it is still not clear whether the observed immunological changes are due to a direct effect of iodine on immune response, or whether they represent a secondary response to a toxic effect of iodine on thyroid tissue. Previous iodine status of a population seems to influence the functional thyroid response to increased iodine intake and possibly the development of thyroid autoimmunity. Moreover, the prevalence of thyroid antibodies, regarded as hallmark of autoimmune thyroid disease, varies between populations under the influence of genetic and environmental factors, and the presence of thyroid antibodies does not always coincide with the presence of thyroid disease or its future development. In addition, the incidence of autoimmune diseases shows a general increasing trend in the last decades. For all these reasons, available data are quite heterogeneous and difficult to analyze and compare. In conclusion, available data from long-term population surveys show that a higher than adequate population iodine intake due to a poorly controlled program of iodine prophylaxis could induce thyroid dysfunction, including thyroid autoimmunity mostly represented by euthyroid or subclinical hypothyroid autoimmune thyroiditis. Close monitoring iodine prophylaxis is therefore advised to ensure that effects of both iodine deficiency and iodine excess are avoided.


Nutrients ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1647 ◽  
Author(s):  
Baldini ◽  
Virili ◽  
D’Armiento ◽  
Centanni ◽  
Ulisse

The inhabitants of Lazio, similarly to those of other Italian regions, have been historically exposed to the detrimental effects of an inadequate intake of iodine. The latter is a micronutrient essential for the biosynthesis of thyroid hormones (TH). Iodine deficiency is responsible for a number of adverse effects on human health known as iodine deficiency disorders (IDD), the most common of which worldwide are goiter and hypothyroidism. In order to reduce IDD, a national salt iodination program was started in Italy in 2005. In this article we reviewed the available data regarding iodine intake in the Lazio population before and after the introduction of the national salt iodination program, in order to evaluate its efficacy and the eventual problem(s) limiting its success. On the whole, the information acquired indicates that, following the introduction of the program, the dietary iodine intake in the Lazio population is improved. There is, however, still much work ahead to ameliorate the iodine prophylaxis in this region. In fact, although a generally adequate iodine intake in school-age children has been observed, there are still areas where a mild iodine insufficiency is present. Moreover, two independent epidemiological surveys on pregnant women evidenced a low urinary iodine concentration with respect to the reference range conceived by the World Health Organization. These findings demonstrate the need for greater attention to the iodine prophylaxis by health care providers (i.e., obstetricians, gynecologists, pediatricians, etc.), and the implementation of effective advertising campaigns aimed at increasing the knowledge and awareness of the favorable effects of iodine supplementation on population health.


Nutrients ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2428 ◽  
Author(s):  
Giordano ◽  
Barone ◽  
Marsico ◽  
Bruno ◽  
Bonofiglio ◽  
...  

Iodine, a micronutrient that plays a pivotal role in thyroid hormone synthesis, is essential for proper health at all life stages. Indeed, an insufficient iodine intake may determine a thyroid dysfunction also with goiter, or it may be associated to clinical features such as stunted growth and mental retardation, referred as iodine deficiency disorders (IDDs). Iodine deficiency still remains an important public health problem in many countries, including Italy. The effective strategy for the prevention and control of IDDs is universal salt iodization, which was implemented in Italy in 2005 as a nationwide program adopted after the approval of an Italian law. Despite an improvement in the iodine intake, many regions in Italy are still characterized by mild iodine deficiency. In this review, we provide an overview of the historical evolution of the iodine status in the Calabria region, located in the South of Italy, during the past three decades. In particular, we have retraced an itinerary from the first epidemiological surveys at the end of the 1980s to the establishment of the Regional Observatory of Endemic Goiter and Iodine Prophylaxis, which represents an efficient model for the surveillance of IDDs and monitoring the efficacy of iodine prophylaxis.


2017 ◽  
Vol 15 (2) ◽  
pp. 114-119 ◽  
Author(s):  
Lalit Narayan Chaudhary ◽  
Saroj Khatiwada ◽  
Basanta Gelal ◽  
Sharad Gautam ◽  
Madhab Lamsal ◽  
...  

Background: Iodine deficiency, thyroid dysfunction and development of thyroid autoimmunity during pregnancy may affect mother and the developing fetus. This study was carried out to find iodine status, thyroid dysfunction and thyroid autoimmunity among pregnant women.Methods: Ninety two pregnant women from three districts of eastern Nepal (Sunsari, Morang and Jhapa) were enrolled for the study, and urine and blood samples were collected. Urinary iodine concentration (UIC), free thyroxine (free T4), thyroid stimulating hormone (TSH), thyroglobulin and anti-thyroid peroxidase (TPO) antibody levels were estimated.Results: The median UIC, mean free T4 and TSH, median thyroglobulin and anti-TPO antibody in the pregnant women were 282.2 (158.42-376) μg/L, 1.14±0.41 ng/dL, 4.57±2.56 IU/mL, 6.5 (4.0-11.0) ng/mL, 1.52 (0.97-2.23) IU/mL respectively. In sufficient (<150 μg/L), adequate (150-249 μg/L) and above requirements (250-499 μg/L) iodine intake was observed in 17 (18.5%), 22 (23.9%) and 53 (57.6%) women respectively. Subclinical hypothyroidism and overt hypothyroidism were seen in 18 (19.5%) and 1(1.1%) women, respectively. Elevated thyroglobulin (>40 ng/mL) and positive anti-TPO antibody was observed in three (3.26%) women for both.Conclusions: Iodine intake was sufficient among pregnant women recently, however, chronic iodine deficiency persisted in small fraction of pregnant women. Mild thyroid dysfunction was common, and thyroid autoimmunity was present in small portion of Nepalese pregnant women population.Keywords: Anti-thyroid peroxidase antibody; Iodine deficiency; Nepal; pregnant women; thyroid dysfunction.


1997 ◽  
Vol 47 (1) ◽  
pp. 87-92 ◽  
Author(s):  
István Szabolcs ◽  
Jan Podoba ◽  
Joachim Feldkamp ◽  
Orsolya Dohán ◽  
Ildikó Farkas ◽  
...  

Author(s):  
Mark P. J. Vanderpump

Thyroid disorders are among the most prevalent of medical conditions. Their manifestations vary considerably from area to area and are determined principally by the availability of iodine in the diet. The limitations of epidemiological studies of thyroid disorders should therefore be borne in mind when considering the purported frequency of thyroid diseases in different communities (1). Almost one-third of the world’s population live in areas of iodine deficiency and risk the consequences despite major national and international efforts to increase iodine intake, primarily through the voluntary or mandatory iodization of salt (2). The ideal dietary allowance of iodine recommended by the WHO is 150 μ‎g iodine/day, which increases to 250 μ‎g in pregnancy and 290 μ‎g when lactating. The WHO estimates that two billion people, including 285 million school-age children still have iodine deficiency, defined as a urinary iodine excretion of less than 100 μ‎g/l. This has substantial effects on growth and development and is the most common cause of preventable mental impairment worldwide. In areas where the daily iodine intake is below 50 μ‎g, goitre is usually endemic, and when the daily intake falls below 25 μ‎g, congenital hypothyroidism is seen. The prevalence of goitre in areas of severe iodine deficiency can be as high as 80%. Iodization programmes are of proven value in reducing goitre size and in preventing goitre development and cretinism in children. Goitrogens in the diet, such as thiocyanate in incompletely cooked cassava or thioglucosides in Brassica vegetables, can explain some of the differences in prevalence of endemic goitre in areas with similar degrees of iodine deficiency. Autonomy can develop in nodular goitres leading occasionally to hyperthyroidism, and iodization programmes can also induce hyperthyroidism, especially in those aged over 40 years with nodular goitres. Autoimmune thyroiditis or hypothyroidism has not been reported to complicate salt iodization programmes. Relatively little prevalence data exist for autoimmune thyroid disease in areas of iodine deficiency (3). In iodine-replete areas, most people with thyroid disorders have autoimmune disease, ranging through primary atrophic hypothyroidism, Hashimoto’s thyroiditis, to hyperthyroidism caused by Graves’ disease. Cross-sectional studies in Europe, the USA, and Japan have determined the prevalence of hyperthyroidism, hypothyroidism, and the frequency and distribution of thyroid autoantibodies in different, mainly white, communities (1, 4–6). Recent US data have revealed differences in the frequency of thyroid dysfunction and serum antithyroid antibody concentrations in different ethnic groups (6), whereas studies from Europe have revealed the influence of dietary iodine intake on the epidemiology of thyroid dysfunction (7). Studies of incidence of autoimmune thyroid disease have only been conducted in a small number of developed countries (8–11). Following a review of the available epidemiological data, the value of screening adult populations for autoimmune thyroid disease will be considered.


2007 ◽  
Vol 51 (5) ◽  
pp. 701-712 ◽  
Author(s):  
Meyer Knobel ◽  
Geraldo Medeiros-Neto

Iodine is a trace element that is essential for the synthesis of thyroid hormone. Both chronic iodine deficiency and iodine excess have been associated with hypertrophy and hyperplasia of follicular cells, attributed to excessive secretion of TSH. This may be associated to thyroid cancer risk, particularly in women. Experimental studies have documented thyroid cancer induction by elevation of endogenous TSH, although in a small number of animals. Iodine deficiency associated with carcinogenic agents and chemical mutagens will result in a higher incidence of thyroid malignancy. Inadequate low iodine intake will result in increased TSH stimulation, increased thyroid cell responsiveness to TSH, increased thyroid cell EGF-induced proliferation, decreased TGFbeta 1 production and increased angiogenesis, all phenomena related to promotion of tumor growth. Epidemiological studies associating iodine intake and thyroid cancer led to controversial and conflicting results. There is no doubt that introduction of universal iodine prophylaxis in population previously in chronic iodine-deficiency leads to a changing pattern of more prevalent papillary thyroid cancer and declining of follicular thyroid cancer. Also anaplastic thyroid cancer is practically not seen after years of iodine supplementation. Iodine excess has also been indicated as a possible nutritional factor in the prevalence of differentiated thyroid cancer in Iceland, Hawaii and, more recently, in China. In conclusion: available evidence from animal experiments, epidemiological studies and iodine prophylaxis has demonstrated a shift towards a rise in papillary carcinoma, but no clear relationship between overall thyroid cancer incidence and iodine intake.


2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Cheng Han ◽  
Xinghai Xia ◽  
Aihua Liu ◽  
Xiaowen Zhang ◽  
Mi Zhou ◽  
...  

Thyroid hormone (TH) affects many metabolic processes such as promoting oxidation of sugar, fat, and protein in many tissues. Thyroid dysfunction is associated with metabolic disorders. The newly discovered adipocyte- and hepatocyte-derived cytokine, betatrophin, has been reported to be involved in metabolic diseases, but its influence on thyroid dysfunction is uncertain. Therefore, the present study aims to evaluate circulating betatrophin levels in subjects with different thyroid function status and to predict the factors associated with betatrophin levels, especially whether thyroid stimulating hormone (TSH), TH, or thyroid autoantibodies are associated with betatrophin levels. In the study, serum betatrophin was measured in the subjects grouped as overt hypothyroidism (OH), subclinical hypothyroidism (SCH), euthyroid with isolated thyroid peroxidase antibody positivity (isolated Ab), and healthy control (HC), according to their thyroid functions. From our results, we found that betatrophin may be associated with thyroid insufficiency but not thyroid autoimmunity. Thus, when interpreting the results of betatrophin, thyroid functions should also be taken into consideration.


1997 ◽  
Vol 43 (5) ◽  
pp. 8-12
Author(s):  
E. P. Kasatkina ◽  
D. E. Shilin ◽  
V. P. Fedotov ◽  
T. M. Belosludtseva

The findings of five-year screening for hypothyrosis, carried out in 1242 newborns 6 to 10 years after the Chernobyl accident, are analyzed in order to assess the patterns of thyroid dysfunction in the neonatal period in regions endemic for goiter and evaluate the relationship between this condition and iodine deficiency and radiation contamination of the environment. The incidence of increased level of TTH in the blood (>5 iU/liter) is 3-4 times increased in two controlled districts contaminated with 137Cs at a density of 1-5 and 5-15 Ci/km2 in comparison with the reference (free from radiation) district. The incidence of neonatal thyroid hypofunction directly correlated with the radiation factor and its intensity and negatively with the severity of iodine deficiency. In addition, the mean TTH values (<5 iU/liter) in the newborns, although within the normal range, were 79 and 187%) higher, respectively, than in controls. Analysis of the results of screening for every year showed an outbreak of thyroid dysfunction in 1994, that is, 8 years after the atomic disaster. These data permit us to hypothesize that low-dose ionizing radiation is responsible for disorders of neonatal adaptation of the thyroid system to iodine deficit in the environment and hence, adequate iodine therapy is to be started from the earliest terms of gestation.


2016 ◽  
Vol 35 (4) ◽  
pp. 385-389 ◽  
Author(s):  
Violeta Anastasovska ◽  
Mirjana Kocova

SummaryBackground:Iodine deficiency is associated with goiter and impaired brain function leading to cretinism. An increased frequency of thyroid-stimulating hormone (TSH) measurements above 5 mIU/L on newborn screening points toward an impaired iodine status of the population.Methods:A 13-year retrospective analysis was performed in 228,266 newborns participating in the national thyroid newborn screening program. The TSH concentration was measured in dry blood spots collected by heel stick on filter paper, 48 hours after birth, using fluoroimmunometric DELFIA method.Results:Out of 236,378 live-born infants, 228,266 (96.6%) have been screened for TSH, of which 198,213 (86.8%) were retrospectively evaluated for TSH levels above 5 mIU/L. Neonates with congenital hypothyroidism, prematurity, and low birth weight were excluded from the evaluation, as well as the inadequately sampled neonates (13.2%). A national prevalence of 3.08% newborns (n=6,105) with TSH > 5 mIU/L was found. Higher percentages were noted in two regions of the country, indicating possible mild iodine deficiency in these regions and shifting the overall average to above 3%.Conclusions:Our results indicate overall iodine sufficiency in the Macedonian population. Additional assessment of the iodine intake in the regions with suspected mild iodine deficiency is needed to prevent suboptimal cognitive and psychomotor outcomes.


Sign in / Sign up

Export Citation Format

Share Document