Goiter prevalence and urinary iodide excretion in a formerly iodine-deficient region after introduction of statutory lodization of common salt.

The objective of this epidemiologic study was to determine the volume of the thyroid gland as well as urinary iodine excretion in dependence on age and gender in a population from an area of low natural iodine supply now receiving iodine prophylaxis. In 430 persons from three communities in the province of Carinthia, Austria, we determined thyroid volume via sonography as well as urinary iodide excretion. As in numerous other European countries, natural iodine supply is insufficient in Austria. Therefore, to reduce goiter incidence, iodization of common salt with 10 mg potassium iodide (KI) per kilogram of NaCl was made mandatory in Austria in 1963 by federal law. In 1990, the amount of iodine addition was increased to 20 mg KI per kilogram of NaCl. Our results show that mean urinary iodide excretion in the persons investigated was altogether satisfactory (males: 163.7 microg of iodine per gram of creatinine; females: 183.3 microg of iodine per gram of creatinine). Goiter prevalence was 34.3% in women and 21.3% in men. An increase in goiter occurrence with age was noted in both genders. The increase in goiter prevalence was particularly obvious in the age group older than 40, i.e., among those participants who had spent at least a certain span of their lives in an area of iodine deficiency. Thus, the most likely reason for the persistently high goiter prevalence is not current iodine deficit but rather the high number of goiters that had developed previously at the time of iodine deficiency and were unable to undergo regression in spite of today's comparatively good iodine supply situation.     

First beneficial results of the implementation of Croatian new law on salt iodination

Presented pilot-study on urinary iodine excretion among schoolchildren in main geographic regions of Croatia indicates a significant improvement in iodine excretion only 12 months after introduction of a new mandatory salt iodination with 25 mg KI/kg of salt. Measurements of urine iodine excretion in 663 schoolchildren of both sexes, aged 9-16 years, from Zagreb, Rude, Bednja, Osijek, Dakovo, Rijeka, Pazin and Dubrovnik showed that from 77.9% to 94.8% of subjects have had urinary iodine above 5 microg/dl. Also from 41.2% to 70.8% of children have had urinary iodine excretion above 10 microg/dl. Before introduction of a new law mostly borderline values of urinary iodine excretion were recorded; therefore recent values present significant positive shift and actually they are the best signs of almost adequate iodine intake in Croatian youth. Nevertheless, further measures for improvement of iodine intake are recommendable because still 31% of controlled table-salt samples from households and 15.7% of imported salt samples have had KI level below 20 mg/kg of NaCl. Salt produced in Croatia was (Pag and Nin salt plants) completely in accordance with iodination regulations. On the other hand, as recent increase in urinary iodine excretion could not be simultaneously followed by reduction in goiter prevalence, in the following years further epidemiological surveys of iodine deficiency disorders shall be warranted.     

Epidemiological survey on the relationship between different iodine intakes and the prevalence of hyperthyroidism

OBJECTIVE: To investigate the effect of different levels of iodine intake on the prevalence of hyperthyroidism and the impact of universal salt iodization on the incidence of hyperthyroidism. DESIGN: A comparative cross-sectional and longitudinal survey was conducted in three areas with borderline iodine deficiency, mild iodine excess (previously mild iodine deficiency) and severe iodine excess. Universal salt iodization had been introduced 3 years previously except in the area with borderline iodine deficiency. METHODS: In total 16 287 inhabitants from three areas answered a questionnaire concerning the history of thyroid disease. Among them 3761 unselected subjects received further investigations including thyroid function, thyroid autoantibodies, thyroid ultrasonography and urinary iodine excretion. RESULTS: Among areas with median urinary iodine excretion of 103 microg/l, 375 microg/l and 615 microg/l (P<0.05), the prevalence of hyperthyroidism did not differ significantly (1.6%, 2% and 1.2%). The prevalence of subclinical hyperthyroidism was higher in areas with borderline iodine deficiency and mild iodine excess than in the area with severe excess iodine intake (3.7%, 3.9% and 1.1%, P<0.001). The prevalence of Graves' disease and its proportion in hyperthyroidism did not differ among areas. The incidence of hyperthyroidism did not significantly increase after the introduction of universal salt iodization. CONCLUSION: Different iodine intakes under a certain range do not affect the prevalence and type of hyperthyroidism. Subclinical hyperthyroidism is more prevalent in the iodine deficient area than in the severe iodine excessive area. In the area with mild iodine deficiency, the introduction of universal salt iodization may not be accompanied by an increased incidence of hyperthyroidism.     

Iodine deficiency in Azerbaijan after the discontinuation of an iodine prophylaxis program: reassessment of iodine intake and goiter prevalence in schoolchildren.

The goal of this study was to assess the prevalence of iodine deficiency (ID) in Azerbaijan after the discontinuation of an iodine prophylaxis program by assessing the prevalence of goiter, iodine intake, and thyroid function. The study included 942 schoolchildren (475 boys and 467 girls) ages 8-14 years, from 13 distinct regions. The survey included the following: (1) clinical evaluation; (2) assessment of thyroid volume both by ultrasound and by palpation; (3) determination of iodide in a morning urine specimen using the classic Sandel-Kolthoff reaction in 347 schoolchildren; (4) determinations of thyrotropin (TSH), triiodothyronine (T3), thyroxine (T4), thyroglobulin (Tg), and anti-thyroid peroxidase (TPO) in serum (n = 165) and TSH in whole blood spotted on filter paper (n = 942). The prevalence of goiter for the whole country was determined by ultrasound (US) to be 86% and by palpation 66%, reaching 100% in the mountainous regions of Caucasus. The median urinary iodine excretion (UIE) was 54 microg/L, reaching level of 26 and 39 microg/L in the Caucasus region. In conclusion, according to the World Health Organization (WHO) classification, Azerbaijan now has mild to moderate ID (median UIE, 54 microg/L) and in the mountainous regions with severe ID. The high prevalence of goiter and the low UIE emphasizes the need for urgent medical reintervention. An iodination program is now implemented by our team in the mountainous regions under the auspice of the government of Azerbaijan.     

Thyroid volume and urinary iodine excretion in the schoolchild population of a Northwestern Italian sub-Alp metropolitan area

Iodine deficiency is recognised as a major preventable public-health worldwide problem. The aim of this study is to assess local reference values for thyroid volume, and give a snapshot of the epidemiology of goiter and iodine nutritional status of the Turin schoolchild population. Sonographic thyroid volume and median urinary iodine excretion were obtained in 1067 schoolchildren aged 11-15 yr resident in Turin for more than 5 yr to assess both goiter prevalence and iodine intake. All the subjects were asked to fill in a questionnaire about their life habits. Anamnestic and anthropometric data, thyroid volume by both bimanual palpation and ultrasonography were assessed, and spot urinary iodine samples were collected. The results show that the median urinary iodine concentration is 113.1 microg/l and the prevalence of goiter <5%, indicating this area as iodine-sufficient. Nevertheless, 40.5% of the schoolchild population has urinary iodine levels lower than the cut-off level recommended as iodine-sufficiency. Interestingly, the high relative prevalence of ultrasound features of autoimmune thyroid disease suggests autoimmune-thyroiditis as a frequent thyroid disease in Turin schoolchildren. As no active programs of salt, milk or water iodisation have ever been carried out, a silent iodine prophylaxis has probably occurred in the city. Despite a sufficient median urinary iodine excretion, a focused program of iodine prophylaxis should be developed due to the presence of a large rate of iodine-deficient population.     

Goiter prevalence and urinary iodine status in urban and rural/mountain areas of Piedmont region

Piedmont region was reported in the 70s as a mild iodine-deficient area with a goiter prevalence > 10%. This study aimed at characterizing the current status of iodine deficiency in Piedmont, with special attention to putative differences between urban and rural/mountain areas. A cross-sectional, observational study was performed according to the surveillance methods for iodine deficiency disorders recommended by the World Health Organization (WHO). Ultrasound local thyroid volume reference values and median urinary iodine concentration were obtained in 2178 schoolchildren aged 11-15 yr, resident in Piedmont region for more than 5 yr to assess both goiter prevalence and iodine intake. Anamnestic and anthropometric data, thyroid volume by both bimanual palpation and ultrasound were assessed, and spot urinary iodine samples were collected. The median urinary iodine concentration was 115.8 microg/l and the prevalence of goiter 3.1%, indicating this area as iodine-sufficient. Nevertheless, 39% of the schoolchild population had urinary iodine levels < 100 microg/l and 6.8% < 50 microg/l. No differences in goiter prevalence and median urinary iodine excretion were observed between urban and rural/ mountain populations. In conclusion, Piedmont is now an iodine-sufficient region. As no programs of salt iodization have been carried out in the last 30 yr, a silent iodine replacement has occurred. Despite a sufficient median urinary iodine excretion, a program of iodine prophylaxis is strongly recommended due to a large part of iodine-deficient population.     

Effect of iodine supplementation on a pediatric population with mild iodine deficiency.

A cross-sectional study in two stages consisted of healthy children to assess the effect of iodine supplementation on a pediatric population with mild iodine deficiency in an ongoing program in the Province of Pontevedra, northwestern Spain. In the first survey (1984), 1565 schoolchildren and in the second survey (1995) 907 schoolchildren were randomly selected from the population. In January 1985, a mandatory consumption of iodized salt in our region was begun. In both surveys we studied prevalence of goiter, urinary iodine excretion, and prevalence of thyroid dysfunction. Similar prevalences of goiter were observed in both surveys, 3.7% versus 3.9%; however, significantly lower prevalence of Ib and II degree goiters were observed in the second survey. The mean iodine excretion was 88.6 +/- 73 microg/L (median 66.3) and 146.4 +/- 99 microg/L (median 115.7), p < 0.01 for the first and second surveys, respectively. Finally, the overall prevalence of thyroid dysfunction was similar in both surveys, 9.2% versus 7.0%; however, significantly lower prevalence of suppressed serum thyrotropin (TSH), considered as a marker of subclinical hyperthyroidism, was observed in the second survey when compared to the first, 0.1% versus 2%, p < 0.01. Our results are in agreement with the recent data from Denmark, where the prevention of subclinical hyperthyroidism occurring in the elderly as a consequence of longstanding mild iodine deficiency is the reason that the Danish finally started iodine supplementation on a national basis. In conclusion, long-term correction of mild iodine deficiency in a pediatric population has beneficial effects on the prevalence of high-degree goiters, and this correction reduces significantly the prevalence of subclinical hyperthyroidism. The present observation constitutes a strong argument for correcting even mild iodine deficiency.     

Sustainable control of iodinedeficiency in Iran: beneficial results of the implementation of the mandatory law on salt iodization

Iodine deficiency disorders (IDD) were prevalent in the Islamic Republic (IR) of IRAN before 1989, when the national salt iodization program with 40 mg l/k of salt was initiated. Despite a comprehensive IDD control program, less than 50% of the households in rural areas consumed iodized salt by 1994. A law for the mandatory production of iodized salt for households was passed in 1994. The purpose of this study was to evaluate goiter status and urinary iodine excretion 2 yr after this law was implemented. In each of 26 provinces, 30 groups of 40 schoolchildren, total 36,178, were examined for goiter and classified according to World Health Organization (WHO) classification. Urinary iodine excretion was measured in 2,917 children by digestion method. Goiter was endemic in all provinces, but the majority were small (grade 1) goiter. Median urinary iodine was 20.5 microg/dl 85.1% had urinary iodine > or =10 microg/dl. Median urinary iodine was above 13 microg/dl in all 26 provinces. In all provinces the percentage of schoolchildren with urinary iodine <5 microg/dl was less than 16%. In nine provinces the median urinary iodine was between 13 to 20 microg/dl; urinary iodine of their schoolchildren was <5 microg/dl in 10.8% and <2 microg/dl in 6-9%. No significant difference was observed between boys and girls or children of rural and urban regions in urinary iodine excretion. We conclude that 7 yr after the beginning of salt iodization and 2 yr following mandatory iodized salt consumption, urinary iodine excretion is adequate in schoolchildren; considering the data of the percent of households consuming iodized salt and programmatic setting of the IDD program, The IR of Iran has reached a sustainable control program for iodine deficiency.     

Continuous rise of urinary iodine excretion and drop in thyroid gland size among adolescents in Mecklenburg-West-Pomerania from 1993 to 1997.

Improved legislation (1989, 1993), as well as education of the public, are likely to improve the iodine supply for the German population. Children and adolescents will be the first to profit. We investigated thyroid size and urinary iodine excretion in a total of 2906 students aged 10 to 18 in Mecklenburg-West-Pomerania in 1993, 1995, and 1997. The median urinary iodine excretion rose from 73 microg/g creatinine in 1993 to 133 microg/g in 1997. The prevalence of goiter, according to the reference range of Gutekunst, dropped from 33% to 10% over the same interval, and the median thyroid size declined from 11 ml to 6 ml. While only 6% of the test subjects excreted more than 150 microg iodine per g creatinine in 1993, this figure rose to 33% in 1997. The improved alimentary iodine supply is due to the increased use of iodine enriched salt by the food industry, food factories and in common food supply services.     

Thyroid autoimmunity is associated with higher urinary iodine concentrations in an iodine-deficient area of Northwestern Greece.

Northwestern Greece was identified in the 1960s for its high prevalence of endemic goiter and iodine deficiency. Although iodized salt has been commercially available since then, a recent epidemiological survey of 3916 schoolchildren found that low-grade goiter is still prevalent in endemic proportions (21%). The aim of this study was to further assess the cause of goiter and the severity of iodine deficiency in children from this endemic area of Greece. Of the 800 children with clinically detectable goiter, 97 children (60 girls and 37 boys, 8-15 years) were recruited for determination of urinary iodine excretion, as well as assessment of thyroid volume and function and detection of antithyroid antibodies. The median urinary iodine concentration was 8.4 microg/dL, indicative of a mild iodine deficiency. Thyroid function was normal in all but 11 children who had subclinical hypothyroidism. Sixteen children (16.5%), including all those with subclinical hypothyroidism, were positive for antithyroid antibodies. Their median urinary iodine concentration (20.6 microg/dL) was higher compared to children who were negative for antibodies (7.4 microg/dL; p<0.001). The mean thyroid volume by ultrasonography (12.2+/-4.1 mL) was above the upper limit of normal for this age group. Thyroid volume was inversely related to the urinary iodine content in the children with negative antithyroid antibodies. Iodine deficiency is still prevalent in northwestern Greece although of mild severity and constitutes the primary cause of goiter among schoolchildren. However, it appears that autoimmune thyroiditis is emerging as a frequent cause of goiter in those children with sufficient iodine intake.     

Iodine nutrition, nodular thyroid disease, and urinary iodine excretion in a German university study population.

We determined the influence of different nutritional factors on the urinary iodine excretion in an East German university population. First, we assessed iodine excretion in spot urine samples. Second, we measured iodine content in the university canteen meals, where approximately 20% of the probands had regular meals. Third, we used a special food questionnaire to assess for other sources of nutritional iodine intake, namely iodine tablets, fish consumption, etc. Fourth, we determined the actual prevalence of goiter and thyroid nodules in our probands by high-resolution ultrasonography. The mean urinary iodine excretion in our cohort was 109 +/- 81 microg/g level indicating a borderline adequate iodine intake (100-200). The frequency of thyroid nodules was 30% and the frequency of goiter 11%. Thyroid volumes greater than 18 mL and 25 mL were considered to be enlarged in adult women and men respectively. Urinary iodine excretion was not related to the presence of goiter or thyroid nodules. In addition urinary iodine excretion did not vary with regular consumption of canteen meals, which contained approximately 50% of the daily recommended iodine intake. In contrast probands with regular supplementary intake of iodine tablets had significantly higher values of urinary iodine excretion (169 +/- 130 microg/g) compared to participants without (103 +/- 87 microg/g). No other single nutritional factor (e.g., salt, milk, or bread) had a statistically significant impact on urinary iodine excretion or was able to raise the urinary iodine excretion above the level of marginal iodine deficiency. In summary, the nutritional iodine intake in a Saxonian study population was found to be close to the margin of iodine deficiency. This shows insufficient supplementation of iodine through iodized salt/industrialized food production.     

天津市食盐加碘后甲状腺肿大率与碘营养状况的调查

目的：调查和研究食盐加碘后天津市居民的甲状腺肿大率和碘营养状况,方法：在6个区共调查居民31530人,7－14岁在校儿童4415人,对调查对象进行甲状腺肿大率,尿碘浓度,食盐碘含量等项目的调查。结果：（1）食盐加碘后天津市居民的平均甲状腺肿大率为5．5％,8－10岁儿童平均甲状腺肿大率为19．7％,甲状腺肿大率较食盐加碘以前有了明显下降,但下降的速度较缓慢,（2）天津市食盐加碘以后各区居民的平均尿碘中位数为287．2ug/L,各区儿童尿碘中位数平均为271．6u/L,证明总体人群碘营养充足,（3）天津市居民总体盐碘含量超过20mg/kg水平,各区居民户盐含碘量有9．9％－41．1％超过60mg/kg,说明碘盐的含碘是偏高是一个新的现象。结论：经过3年左右的食盐加碘防治工作,天津市碘缺乏情况已得到控制。     

Introduction of iodized salt to severely iodine-deficient children does not provoke thyroid autoimmunity: a one-year prospective trial in northern Morocco.

To determine if introduction of iodized salt induces thyroid autoimmunity in goitrous children, we conducted a prospective trial in iodine-deficient Moroccan schoolchildren (n = 323). Local salt was iodized at 25 microg iodine per gram of salt and distributed to households. Before introduction of iodized salt and at 10, 20, 40, and 52 weeks, we measured antithyroid peroxidase antibodies (TPO-Ab), antithyroglobulin antibodies (Tg-Ab), urinary iodine (UI), and thyroid hormones, and examined the thyroid using ultrasound. At baseline, median UI was 17 microg/L and the prevalence of goiter and hypothyroidism was 72% and 18%, respectively. Provision of iodized salt maintained median UI at 150-200 microg/L for the year (p < 0.0001). There was a significant increase in mean total thyroxine (T(4)) and a significant reduction in the prevalence of hypothyroidism (p < 0.001). There was a transient increase in the prevalence of detectable antibodies after introduction of iodized salt (p < 0.0001) with levels returning to baseline at 1 year. Only congruent with 1% of children had elevated TPO-Ab and none had elevated Tg-Ab over the course of the study, and no child with elevated TPO-Ab had abnormal thyrotropin (TSH) or T(4) concentrations. None developed clinical or ultrasonographic evidence of thyroid autoimmune disease and/or iodine-induced hypothyroidism or hyperthyroidism. Rapid introduction of iodized salt does not provoke significant thyroid autoimmunity in severely iodine-deficient children followed for 1 year.     

Epidemiological survey of thyroid volume and iodine intake in schoolchildren,postpartum women and neonates living in Ulaan Baatar

OBJECTIVE: Although endemic goiter had been recognized in most parts of the country, there are few available data on iodine-deficiency disorders (IDDs) in Mongolia. This study aimed to characterize the current status of iodine deficiency in Ulaan Baatar, Mongolia's capital city. DESIGN: Cross-sectional, observational study designed and performed according to the surveillance methods for IDD prevalence recommended by WHO/UNICEF/ICCIDD. SUBJECTS: A total of 505 schoolchildren aged 9-14 years (237 girls and 268 boys) and 138 mothers and their neonatal infants were selected to clinical and biochemical examination of the thyroid in 1996 and 1999. MEASUREMENTS: The anthropometric measurements, thyroid volume determined by ultrasound, blood TSH and FT4 concentrations, urinary iodine concentration and iodine content of salt consumed in households. RESULTS: Median thyroid volumes based on age were generally higher than those in iodine-sufficient areas and comparative to those reported in mild iodine-deficiency areas. Application of the updated WHO/ICCIDD reference values in iodine-replete European schoolchildren to the Mongolian children aged 10-12 years resulted in a goiter prevalence of 43.3%. The median value of urinary iodine concentration was 152.5 micro g/l (1.20 micro mol/l) and 40.3% of children excreted iodine below 100 micro g/l. Iodized salt (> 40 ppm) was consumed in 63.1% of households and in the children using noniodized salt their urinary iodine concentration was lower than those using ionized salt. In postpartum women, median thyroid volume and urinary iodine concentration were 11.3 ml and 107 micro g/l (0.84 micro mol/l), respectively, and 46% of women excreted less than 100 micro g/l (0.79 micro mol/l) of iodine. Of their neonates, 17.8% had elevated blood TSH levels (> 5 mU/l). In a 1999 survey, the goiter prevalence and ratio of low iodine excretion in schoolchildren decreased to 29.8% and 31.3%, respectively, while median urinary iodine concentration remain unchanged (160 micro g/l; 1.26 micro mol/l). CONCLUSION: The present study clearly indicates the presence of mild iodine deficiency in Mongolia. Enlarged thyroid gland and normal iodine excretion observed in schoolchildren living in Ulaan Baatar may result from the residual effects of iodine deficiency previously and presumably still exist in the city. Slight reduction in the rate of children with enlarged thyroid and low urinary iodine excretion after the onset of national iodinization programme suggests incomplete normalization of thyroid volume in children and that the correction of iodine deficiency is now in progress in Ulaan Baatar. Further nationwide surveys together with monitoring the progress of the national programme eliminating IDD are required in suburban areas surrounding the city and also in rural areas.     

Croatia has reached iodine sufficiency

This study was performed in 2002, 6 yr after the introduction of a new regulation on salt iodination with 25 mg KI/kg of salt. The aim of the study was to evaluate whether further significant positive results of improved iodine intake could be observed among schoolchildren in Croatia. A total of 927 schoolchildren of both sexes, aged 6-12 yr, were included in the study. In Croatia, with a population of 4,437,460 the research was implemented in four major geographical regions: the Northwestern, Slavonia, Northern Adriatic and Dalmatian regions. Investigations included randomly selected pupils from regional centers and neighboring smaller towns or villages. The results have revealed that thyroid volumes were within the normal range according to the provisional WHO/ICCIDD reference values for sonographic thyroid volume in iodine-replete school-age children, updated in 2001. A significant improvement in medians of urinary iodine excretion was detected in 2002: from 9 microg/dl in 1991 to 14.6 microg/dl in Zagreb, from 4.3 microg/dl in 1995 to 13.1 microg/dl in Split, from 9.4 microg/dl in 1997 to 14.2 microg/dl in Rijeka and from 13.4 microg/dl in 1997 to 14.7 microg/dl in Osijek. An overall median of 14.0 microg/dl of urinary iodine excretion was detected in Croatian schoolchildren. The control of salt at different levels, from production to consumption, including salt produced in all three Croatian salt plants and imported salt, revealed that Croatian salt is adequately iodized. From severe iodine deficiency before the 1950s, through mild-to-moderate iodine deficiency in the 1990s, Croatia has now reached iodine sufficiency.     

Environmental iodine intake affects the type of nonmalignant thyroid disease.

The relationship between the iodine intake level of a population and the occurrence of thyroid diseases is U-shaped with an increase in risk from both low and high iodine intakes. Developmental brain disorders and endemic goiter caused by severe iodine deficiency may seriously deteriorate overall health status and economic performance of a population. Severe iodine deficiency with a median 24-hour urinary iodine excretion of the population below 25 microg needs immediate attention and correction. Less severe iodine deficiency with median urinary iodine excretion below 120 microg per 24 hours is associated with multinodular autonomous growth and function of the thyroid gland leading to goiter and hyperthyroidism in middle aged and elderly subjects. The lower the iodine intake, the earlier and more prominent are the abnormalities. At the other end of the spectrum, severely excessive iodine intake starting at median urinary iodine excretion levels around 800 microg per 24 hours is associated with a higher prevalence of thyroid hypofunction and goiter in children. A number of studies indicate that moderate and mild iodine excess (median urinary iodine >220 microg per 24 hours) are associated with a more frequent occurrence of hypothyroidism, especially in elderly subjects. The exact mechanism leading to this has not been clarified, and more studies are needed to define the limits of excessive iodine intake precisely. Due to the frequent occurrence of thyroid disorders, proper monitoring and control of the population iodine intake level is a cost-effective alternative to diagnosing, therapy and control of the many individual cases of thyroid diseases that might have been prevented.     

2008年浙江省舟山市海岛地区甲状腺疾病流行病学调查

目的 调查浙江省舟山市海岛地区食用非加碘盐的居民患甲状腺疾病状况及致甲状腺疾病的相关影响因素.方法 2008年在浙江省舟山市岱山县对737名食用非加碘盐的居民进行流行病学问卷调查、甲状腺B超检查、甲状腺功能及尿碘测定;同时抽查了183名8～10岁儿童(均为食用非加碘盐居民的子女)的尿碘.结果 舟山市岱山县食用非加碘盐的居民尿碘中位数(MUI)为122.2 μg/L,8～10岁儿童MUI为123.7μg/L;甲状腺肿、甲状腺癌、甲状腺功能亢进(简称甲亢)、亚临床甲状腺功能亢进(简称亚临床甲亢)和亚临床甲状腺功能减退(简称亚临床甲减)的患病率分别为39.9%、0.4%、0.4%、0.7%和0.8%.logistic回归分析显示,甲状腺肿患病率无性别差异(P>0.05),而年龄是甲状腺肿发生的危险因素(P<0.05);甲状腺肿、甲亢患病情况与饮食史、吸烟史、饮酒史、饮茶史、尿碘水平均无明显相关关系(P均>0.05).结论 舟山市海岛地区食用非碘盐居民碘摄入适量,但甲状腺肿和甲亢患病率较高.     

Reappraisal of the risk of iodine-induced hyperthyroidism: an epidemiological population survey

The occurrence of iodine-induced hyperthyroidism (IIH) has been reported after iodine supplementation from clinics and hospitals, but not following an epidemiologic survey. We studied the prevalence of thyroid derangement in a population following iodine supplementation. One yr after more than 75% of the population had been consuming 40 ppm iodized salt; information regarding history of endemic goiter and iodized salt production, distribution, consumption and monitoring were collected in four cities of the Islamic Republic of Iran. A total of 6048 subjects were randomly selected. All subjects were assessed for size of goiter, and urinary iodine and serum T4, T3, TSH, anti-thyroglobulin and anti-thyroperoxide were measured. Before iodine supplementation, all four cities were areas of endemic goiter. The rate of household consumption of iodized salt was 50, 75 and 90% in 1994, 1995 and 1996, respectively. Ninety-one percent of the salt samples contained 15-55 ppm iodide. Total goiter rate was 57, 62 and 68%; median urinary iodine was 188, 197 and 190 microg/l in the age groups of 6-18, 19-40 and >40 yr, respectively. Prevalence of clinical and subclinical hyperthyroidism was 0.34 and 0.41 and those of clinical and subclinical hypothyroidism were 0.51 and 1.07%, respectively. Nine point eight and 18% in the 19-40 yr age group and 17.6 and 25.6% in >40 yr old subjects had positive anti-thyroperoxidase and anti-thyroglobulin, respectively. This systemic epidemiologic study in an iodine deficient population showed that, following a well-executed iodine supplementation program, the occurrence of IIH is rare.     

Silent iodine prophylaxis in Western Europe only partly corrects iodine deficiency; the case of Belgium

OBJECTIVE: Belgium is one of the Western European countries in which no program of iodine-deficiency correction using iodized salt has been implemented, in spite of well-documented mild iodine deficiency. In 1995, the median urinary iodine concentration was 55 microg/l (normal: 100-200) and the prevalence of goiter was 11% (normal: below 5%) in representative samples of schoolchildren aged 6-12 years. Based on these results, the authors of the present study and others had emphasized to health professionals and to the public the necessity for iodine supplementation. The objective of this study was to evaluate as to whether these efforts had resulted in an improvement in the status of iodine nutrition. DESIGN: We performed a national survey of the status of iodine nutrition in Belgium based on the determination of thyroid volume, obtained by ultrasonography, and urinary iodine concentrations in schoolchildren. METHODS: A mobile van equipped with an ultrasound instrument, a computer and a deep-freeze visited 23 schools selected from across the country. The sample included 2855 schoolchildren (1365 boys and 1490 girls) aged 6-12 years. RESULTS: The results show a homogeneous situation in the whole country, with a median urinary iodine concentration of 80 microg/l and a goiter prevalence of 5.7%. Urinary iodine slightly decreases with age in girls and reaches a critical value of 59 microg/l at the age of 12 years, together with a goiter prevalence of 18.4%. CONCLUSION: Iodine nutrition has improved slightly in Belgium but mild iodine deficiency continues, with public-health consequences. The improvement indicates silent iodine prophylaxis, as no official salt-iodization measures have been taken. Silent iodine prophylaxis only partly corrects iodine deficiency in Western Europe. Active measures, including the implementation of a program of salt iodization, are urgently required.     

Iodine deficiency in Calabria: characterization of endemic goiter and analysis of different indicators of iodine status region-wide

The distribution of goiter prevalence in schoolchildren (no.=13,984, age 6-14 yr), the neonatal TSH results obtained from the congenital hypothyroidism screening program and the urinary iodine excretion values (no.=284) were employed for the assessment of iodine deficiency in Calabria, a Southern Italy region. Data were collected during the years 1990-1996. In the inland territory, goiter prevalence ranged from 19 to 64%. At sea level, there was a great variability of goiter prevalence, with values varying from 5.3 to 25.7%. The analysis of the neonatal hypothyroidism screening program data (no.=21,078) showed a 14.8% frequency of TSH levels >5 microU/ml whole blood in newborns from the inland territory and a 14.1% frequency at sea level. Urinary iodine excretion resulted (mean+/-SD) 53.8+/-43.4 microg/l (range: <20 to 189 microg/l) in the inland territory and 89.6+/-59.8 microg/l (range: 26 to 333 microg/l) at sea level. Median urinary iodine excretion values in 13 villages or small towns of the inland territory ranged from 31 to 57 microg/l. In 2 major towns located at sea level, the median iodine excretion values were 72 microg/l in Crotone main city and 94 microg/l in Reggio Calabria main city. The data indicated that moderate, with pockets of severe iodine deficiency is present in the inland region while iodine supply varies from sufficient to marginally low in the coastal areas. Mild iodine deficiency was found in a major town located at sea level.