Goiter in Iran

Prevalence of thyroid dysfunction among Iranian older adults: a cross-sectional study

There is limited data on the prevalence of thyroid dysfunction in the older population. This study aimed to determine the prevalence of thyroid dysfunction among a sample of Iranian older adults. A cross-sectional analysis of older adults who aged 60 years and over was conducted. A total of 363 subjects were randomly selected from Birjand longitudinal aging study (BLAS) cohort study. Serum thyroid-stimulating hormone (TSH) level, total thyroxine (T4) and total triiodothyronine (T3) were measured by the enzyme-linked immunosorbent assay (ELISA). Based on thyroid function tests and history of taking medicines used to treat thyroid disorders, participants were classified into the following groups: euthyroid, overt/subclinical hypothyroidism, and overt/subclinical hyperthyroidism. Subsequently, the crude and World Health Organization (WHO) age-standardized prevalence were estimated for different thyroid function categories. A total of 171 men and 192 women, aged 60-94 years, were randomly selected. The crude prevalence of total hypothyroidism was 22.31% (subclinical [18.46%], overt [3.86%]), and that of hyperthyroidism was 1.66% (subclinical [1.38%], overt [0.28%]). The crude prevalence of total thyroid dysfunction was, therefore, 23.97%. A female preponderance was noticed in both total (P-value = 0.035) and overt (P-value = 0.035) hypothyroidism. An increasing trend with age was noticed in the prevalence of total hypothyroidism (P-value = 0.049). Age-standardized prevalence of total hypothyroidism and hyperthyroidism was 26.63% (95% confidence interval [CI] 20.58-33.69%) and 1.11% (95% CI 0.49-2.51%), respectively. A considerable proportion of our study population demonstrated evidence of thyroid dysfunction, particularly subclinical hypothyroidism. Our findings highlight the importance of further investigation of thyroid disorders among older Iranian adults.

Trend of Iodine Status in the Eastern Mediterranean Region and Impact of the Universal Salt Iodization Programs: a Narrative Review

Recognizing the importance of iodine deficiency as a single most important preventable cause of brain damage, World Health Organization (WHO) urged all countries to scale up salt iodization since 1991 where iodine deficiency was declared as a global public health problem. All countries committed to report on the national iodine status of school-aged children (6-12 years), every 3 years. This paper aims to evaluate the progress of countries in Eastern Mediterranean Region (EMR) toward the eradication of iodine deficiency disorders (IDD) and recommend operational action to support implementation of the WHO Regional Nutrition Strategy (2020-2030). Salt iodization in EMR has been scaled up with significant progress in increasing the proportion of dietary salt which is adequately iodized. As a result, many countries such as Qatar, Kuwait, Bahrain, Jordan, Oman, and Iran have achieved, or are now on the threshold of achieving IDD elimination. The WHO in coordination with United Nations Children's Fund is working with member states to ensure suitability of these achievements. Hence, efficient monitoring will help member states to measure the magnitude of IDD as a public health problem and to monitor the effects of the intervention on the iodine status of a population. Policy makers should take proactive steps to enforce mandatory regulatory measures for USI, through a multi-sectoral coordination, and careful assessments and estimates of iodine nutritional status. Coordination between the two national programs of USI and salt reduction intake is necessary.

Continuously sustained elimination of iodine deficiency: a quarter of a century success in the Islamic Republic of Iran

BACKGROUND

Iodine deficiency and related disorders were very common in Iran prior to 1996, when universal salt iodization (USI) was implemented and in 2000 Iran was declared iodine deficiency disorders (IDD) free. The aim of this study was to evaluate the adequacy of iodine intake by Iranian households in all 30 provinces of Iran, a quarter of a century after the intervention.

METHODS

A total of 18,000 school-aged children (8-10 years with mean 8.7 ± 1 year) were included in this study. Urine samples were collected from all children for measurement of urinary iodine excretion and 1800, 210 and 3000 salt samples were randomly collected from the family kitchen, production site of 73 salt factories and distribution circles of 30 provinces, respectively.

RESULTS

The median urinary iodine concentration (UIC) of participants was 161 μg/L. The proportion of children with UIC of, 20-49, 50-99 and ≥ 100 μg/L were 10.3, 15.9 and 73.7%, respectively. The mean (± SD) and median salt iodine values were 28.2 (± 12.6) and 31.7 ppm, at the production site, and 31.5 (± 13.6) and 29.6 ppm at the distribution circles, respectively. About 80% of factory salts had more than 20 ppm iodine. 98% of households consumed iodized salt, 80% had appropriate salt storage, and 83% of the household salts contained ≥ 20 ppm.

CONCLUSIONS

Based on the results of this study, Iranian populations are consuming adequate iodine. The well-maintained and monitored USI program has improved the dietary iodine intakes of the population, and the country has achieved all criteria of a well-controlled IDD program.

Iodine deficiency status in the WHO Eastern Mediterranean Region: a systematic review

Iodine deficiency is a global public health issue because iodine plays a major role in the thyroid hormone synthesis and is essential for normal neurological development. This review summarizes the publications on iodine status in the WHO Eastern Mediterranean Region (EMR) countries. All related studies available in main national and international databases were systematically searched using some specific keywords to find article published between 1909 and 2015. The prevention of iodine deficiency disorders (IDDs) in the WHO EMR countries is currently under control without significant side effects. Mild to severe IDDs exist in some countries of the Middle East, due to lack of effective iodine supplementation program, but the Islamic Republic of Iran, Jordan, Bahrain and Tunisia have achieved the goal of universal salt iodization. Overall, despite enormous efforts to control IDDs, still IDD remains a serious public health problem in some countries of the region, requiring urgent control and prevention measures.

Has iodized salt reduced iodine-deficiency disorders among school-aged children in north-west Iran? A 9-year prospective study

OBJECTIVE

Low iodine intakes are associated with goitre and other iodine-deficiency disorders (IDD) that have affected billions of people worldwide. We aimed to assess total goitre rate (TGR) and urinary iodine concentration (UIC) in schoolchildren between 2007 and 2015, percentage of iodized salt consumption by households, and salt iodine content at production, distribution and household levels in north-west Iran. Design/Setting/Subjects UIC assessed among schoolchildren in nine consecutive years; 240 schoolchildren aged 8-10 years selected by systematic random sampling each year in the West Azerbaijan Province.

RESULTS

Median UIC was >100 μg/l in all years. More than 50 % of children had iodine deficiency (UIC≤99 μg/l) in 2010 and 2011, while this rate was approximately 15-35 % in other years. Proportion with UIC below 50 μg/l was <20 % in all years except 2010 and 2011. Excessive UIC (≥300 μg/l) rate was between 5·4 and 27·5 %. TGR decreased from 44 % in 1996 to 7·6 % and 0·4 % in 2001 and 2007, respectively. Regular surveys from 2002 to 2015 showed that 98 % or more of households consumed iodized salt. Iodine level ≥20 ppm was observed in 87·5, 83 and 73 % of salt at production, distribution and household level, respectively (data from national study in 2007). The last national study in 2014 showed that median iodine level in household salt was 27 ppm.

CONCLUSIONS

Our focused data suggest that the universal salt iodization programme is improving the iodine status of schoolchildren in the West Azerbaijan Province of Iran. Reduction of TGR to less than 5 % in schoolchildren indicates successful elimination of IDD as a major public health problem.

Review of Iodine Nutrition in Iranian Population in the Past Quarter of Century

CONTEXT

Iodine deficiency is one of the most important health problems worldwide. The overall aim of this study was a narrative review of the past and present status of iodine nutrition in the Iranian population to gather and provide valuable background data in this field for future studies.

EVIDENCE ACQUISITION

For this narrative literature review study, published internal (SID, Iran doc, Iran medex) and international (Web of knowledge, Pubmed, SCOPUS) source studies were searched using the following medical subject heading terms: Iodine, IDD (iodine deficiency disorders), UIC (urinary iodine concentration), Goiter, IQ (intelligence quotient), thyroid hormone, Iodine and pregnancy, Iodine and breast feeding, as well as Iodized salt, reporting the prevalence of iodine deficiency and iodine nutrition status of different target populations in Iran over 25 years, between 1988 - 2014, were assessed. We found 185 abstracts by literature search, of which, 161 papers that were as case reports, animal study, with lack of regional or national data were excluded after full text evaluation. Finally 24 full papers covering regional or national data on iodine nutrition of the study population were eligible for our review.

RESULTS

Iodine deficiency, as a nutritional problem, had been identified in Iran since 1968. In the years 1987 - 1989, a few studies were done to define the prevalence of iodine deficiency in the country. The first nation-wide survey was performed in 14 provinces. Based on this survey all provinces were suffering of endemic goiter. In 1989, iodine deficiency was recognized as a major problem for community health. In 1990, salt factories began to produce iodized salt and in 1996, the second national survey was performed in 26 provinces. This survey indicated that 40% of boys and 50% of girls have goiter, with a median urinary iodine excretion of 205 µg/L. The 3rd national survey in 2001 showed that the total goiter rate is 9.8% and median UIC of 165 μg/L. In 2007, the 3th national survey was conducted 17 years after iodized salt consumption by Iranian households. In this study the total goiter rate and median urinary iodine was 5.7% and 145 μg/L, respectively. The 5th national survey conducted in 2013, showed household consumption of iodized salt for all provinces was 98% and the median urinary iodine of school children was 161 μg/L. Following the 5th national survey, the 1st national survey of the iodine status and thyroid function of pregnant women, conducted in 10 provinces in the different region of the country, documented a median UIC for pregnant women of 87.3 µg/L, results of this national survey clarified that despite iodine sufficiency of school children in Iran, pregnant women have moderate iodine deficiency and need iodine supplementation.

CONCLUSIONS

The success of iodine deficiency control program depends on well designed programmatic steps and mandatory iodized salt consumption in certain situations. The iodine intake of school children is sufficient, however, Iranian pregnant women are suffering from moderate iodine deficiency and need iodine supplementation.

Neonatal thyrotropin concentration and iodine nutrition status of mothers: a systematic review and meta-analysis

BACKGROUND

Low maternal iodine intake disturbs the thyroid function of neonates transiently or permanently.

OBJECTIVE

To our knowledge, we conducted one of the first systematic reviews and meta-analyses aimed at exploring the association of neonatal thyrotropin concentrations and iodine status of mothers during pregnancy and early postpartum periods.

DESIGN

Data were collected through literature searches for studies published between 1969 and 2015 with the use of electronic databases. Mean or median maternal urinary iodine and neonatal thyrotropin concentrations, along with other relevant data, were extracted from eligible studies. The quality and risk of bias of each study was assessed.

RESULTS

A random-effects model was used for the analysis. Of 110 studies identified, 25 trials were shown to be eligible for inclusion in the meta-analysis. Mean (95% CI) thyrotropin concentrations of neonates born to mothers with iodine deficiency were higher than in neonates born to mothers with iodine sufficiency during pregnancy in both heel blood samples [1.79 mIU/L (95% CI: 1.61, 1.97 mIU/L) compared with 1.75 mIU/L (95% CI: 1.68, 1.82 mIU/L), respectively] and cord blood samples [11.91 mIU/L (95% CI: 6.67, 17.14 mIU/L) compared with 6.15 mIU/L (95% CI: 4.30, 8.01 mIU/L), respectively]. There were no significant differences in neonatal thyrotropin concentrations of heel samples between mothers with iodine deficiency and those with sufficiency during the early postpartum period; however, the values of thyrotropin in cord samples of neonates born to mothers with iodine deficiency were significantly higher than in neonates born to mothers with iodine sufficiency [11.62 mIU/L (95% CI: 10.47, 12.77 mIU/L) compared with 7.40 mIU/L (95% CI: 6.21, 8.59 mIU/L)].

CONCLUSION

Our findings reveal that, compared with heel blood samples, neonatal thyrotropin in samples collected from the cord are more sensitive to the iodine status of mothers; however, further investigations are required in this regard.

The Association between Cobalt Deficiency and Endemic Goiter in School-Aged Children

BACKGROUND

In Iran, an iodine deficiency control program was initiated in 1989 by iodizing salt. Despite this program, goiters have remained an endemic condition in most parts of Iran. Thus, it is possible that other factors aside from iodine deficiency may contribute to endemic goiter. The aim of this study was to investigate the association between cobalt deficiency and endemic goiter in a region of Iran with a high prevalence of goiter.

METHODS

A cross-sectional study was conducted among school children aged 9 to 11 years in the city of Kerman, Iran. In the first phase of the study, a multistage, proportional-to-size, cluster sampling method was used to screen 5,380 out of 29,787 students. After the screening phase, 170 students (130 goitrous and 40 nongoitrous) were randomly selected, and serum and urine specimens were obtained. We measured thyroid function, serum cobalt level, and urinary iodine excretion. Univariate and multiple logistic regression analyses were performed.

RESULTS

The prevalence of grade 2 goiters was 34.8% (95% confidence interval [CI], 31.5 to 42.5), with both sexes being equally affected. The weight and body mass index of goitrous subjects was significantly lower (P<0.001) than those of nongoitrous subjects. The serum cobalt levels were lower in goitrous subjects than in nongoitrous subjects (4.4±2.9 µg/L vs. 6.4±2.7 µg/L). The urinary iodine levels were also lower in goitrous subjects than in nongoitrous subjects (198.3±108.3 µg/L vs. 270.2±91.1 µg/L). Multiple regression analysis showed that only cobalt deficiency, not iodine deficiency, significantly contributed to the presence of goiter (odds ratio, 0.78; 95% CI, 0.61 to 0.99; P=0.042).

CONCLUSION

Cobalt deficiency may be an important independent predicator for goiter in endemic regions, especially areas in which goiters persist despite salt iodization programs.

Mothers’ behaviour contributes to suboptimal iodine status of family members: findings from an iodine-sufficient area

Objective

Iodine deficiency still remains a major public health concern worldwide despite global progress in its elimination. The aims of the present study were to evaluate dietary iodine status in the mother and one adult member of each family and the association between mothers’ knowledge, attitude and behaviour and the dietary iodine status of adult family members in Tehran.

Design

In this cross-sectional study, 24 h urinary iodine and Na concentrations and the iodine content of household salt were measured. Mothers’ knowledge, attitude and behaviour were assessed using a questionnaire administered in face-to-face interviews.

Setting

Health-care centres from four distinct areas of Tehran.

Subjects

Mother–adult family member pairs aged ≥19 years (n 290), enrolled through randomized cluster sampling.

Results

In mothers and adult family members, median 24 h urinary iodine concentration was 73 (interquartile range (IQR) 36–141) µg/l and 70 (IQR 34–131) µg/l, dietary iodine intake was 143 (IQR 28–249) µg/d and 130 (IQR 26–250) µg/d and dietary salt intake was 8·0 (IQR 5·9–10·2) g/d and 7·5 (IQR 5·3–10·0) g/d, respectively. Significant correlations were observed between mothers’ attitude and behaviour and the 24 h urinary iodine concentration, dietary iodine intake and iodine content of salt of adult family members. In multiple analysis, lower quartiles of salt iodine content and salt intake and inappropriate behaviour scores in mothers increased the risk of urinary iodine concentration <100 µg/l in adult family members.

Conclusions

The present study showed that mothers’ behaviour, but not knowledge and attitude, was among major contributors to the suboptimal dietary iodine status observed in adult family members.

Eighteen years of continuously sustained elimination of iodine deficiency in the Islamic Republic of Iran: the vitality of periodic monitoring

BACKGROUND

Two decades ago the Islamic Republic of Iran was among countries most severely affected by iodine deficiency. Iran has since achieved great success in the control and elimination of iodine deficiency disorders (IDDs) following the national salt iodization program, initiated in 1989. The aim of the study was to evaluate the effectiveness of sustained consumption of iodized salt by Iranian households and the current status of iodine nutrition in all 30 provinces of Iran.

METHODS

Goiters-measured by palpation-and urinary iodine concentration of children were assessed. In this descriptive cross-sectional study, 36,000 schoolchildren (18,000 girls and 18,000 boys), aged 8-10 years, were randomly selected, from October 2007 to February 2008, from 30 provinces of the country. Goiter prevalence and urinary iodine excretion in schoolchildren and the iodine content of salt at household, factory, and distribution site levels were measured.

RESULTS

The goiter rate in the country was 6.5% (6% grade 1 and 0.5% grade 2), and the weighted goiter rate was 5.7%. The total goiter rate in Hamedan, Zanjan, Kermanshah, Mazandaran, and Gilan provinces was over 10%. The median urinary iodine was 140 μg/L. Urinary iodine levels of 20-50, 50-99, and ≥100 μg/L were noted in 15.3%, 19.8%, and 64.9% of the samples, respectively. In four provinces, the median urinary iodine was lower than 100 μg/L. The mean (±SD) and median salt iodine values were 23.2 (±13.8) and 34.7 ppm, respectively, at the production level, and 32.4 (±14.7) and 32.3 ppm, respectively, at the distribution level. Ninety-eight percent of households consumed iodized salt, 58% of households had appropriate salt storage, and 27% of the household salts contained <20 ppm.

CONCLUSIONS

Iran has achieved much in the development of universal salt iodization strategy and elimination of IDDs and currently meets all criteria for sustainable elimination of iodine deficiency. However, the lack of adequate iodine nutrition in some provinces necessitates special attention and proper monitoring.

Differences between subjects with sufficient and deficient urinary iodine in an area of iodine sufficiency

BACKGROUND

Iran has long been recognized as a country of iodine sufficiency; however, recent studies show that the proportion of subjects with insufficient urinary iodine is gradually increasing in Tehran capital city.

AIM

The aim of this study was to evaluate differences between individuals with sufficient and deficient urinary iodine in Tehran.

MATERIAL AND METHODS

In this cross-sectional study, 639 Tehranian adult subjects, aged ≥ 19 yr (242 males, 397 females), were enrolled through randomized cluster sampling. A 24-h urine sample was collected for measurement of urinary iodine, sodium and creatinine concentrations using the digestion method, flame photometry and autoanalyzer assay, respectively. Salt intake was estimated and iodine content of household salt was measured by titration.

RESULTS

Medians (interquartile range) of 24-h urinary iodine concentrations in subjects with sufficient and deficient urinary iodine were 163.0 (126.0-235.0) and 44.0 (26.0-67.0) μg/l, p<0.001, respectively. Salt with iodine content of >20 parts per million was consumed by 77.4 and 38.3% of subjects with sufficient and deficient urinary iodine, respectively (p<0.001). Median daily salt intake in subjects with sufficient urinary iodine was significantly higher than in those with deficient urinary iodine (8.1 vs 7.3 g, p<0.001). No significant differences in the mentioned variables were observed between males and females. Fifty and 30% of subjects with insufficient and sufficient urinary iodine had <7 yr education, respectively (p<0.001).

CONCLUSIONS

Iodine content of salt, the amount of salt intake and education levels differ greatly between subjects with sufficient and deficient urinary iodine in Tehran.

Evaluation of iodine nutritional status in Tehran, Iran: iodine deficiency within iodine sufficiency

BACKGROUND

Production of iodized salt in Iran for household consumption began in 1990. Previous studies have reported sustainable elimination of iodine deficiency disorders in Iran. The aim of this study was to evaluate the iodine nutritional status in Tehran in 2009.

METHODS

In this cross-sectional study, 383 Tehranian households were enrolled through randomized cluster sampling and a total of 639 adult subjects (242 men and 397 women), aged 19 and over, participated. A 24-hour urine sample was collected for measurement of urinary iodine, sodium, and creatinine concentrations using the digestion method, flame photometry, and autoanalyzer assay, respectively. Salt intake was estimated and iodine content of household salt was measured by titration.

RESULTS

Median (interquartile range) iodine content of household salt and urinary iodine concentration (UIC) in Tehran were 21.2 (3.2-31.7) parts per million and 70.0 (34.0-131.2) μg/L, respectively. There was no statistically significant difference in 24-hour UICs between men and women. Median (interquartile range) daily salt intake was 7.6 (5.5-9.8) g, which was not different in the two genders. According to the WHO/ICCIDD/UNICEF classification, 11.2%, 25.9%, 26.7%, 25.1%, 8.0%, and 3.2% of participants had UIC <20, 20-49, 50-99, 100-199, 200-299, and >300 μg/L, respectively.

CONCLUSIONS

Mild iodine deficiency has recurred in Tehranians. The results emphasize the need for continuous monitoring in all regions, even in a country with iodine sufficiency.

Thiocyanate status does not play a role in the etiology of residual goiter in school children of Isfahan, Iran

BACKGROUND

Despite long standing iodine supplementation in Iran the prevalence of goiter remains high in some areas. In the present study we investigated the possible role of thiocyanate as a goitrogen in the etiology of goiter in Isfahan, Iran.

METHODS

A total of 2331 (6-13 year old) school children were selected by multistage random sampling. Thyroid size was estimated in each child by inspection and palpation. Urinary iodine concentration (UIC) and urinary thiocyanate (USCN) were measured.

RESULTS

Overall, 32.9% of the 2331 students had goiter. The median UIC was 195.5 μg/L. The mean ± SD of USCN in goitrous and nongoitrous subjects was 0.42 ± 0.28 mg/dL and 0.41 ± 0.32 mg/dL, respectively (P=0.86). USCN level in goitrous and nongoitrous boys was 0.41 ± 0.32 mg/dL and 0.43 ± 0.37 mg/dL, respectively (P=0.67). USCN level in goitrous and nongoitrous girls was 0.43 ± 0.26 mg/dL and 0.40 ± 0.28 mg/dL, respectively (P=0.43).

CONCLUSIONS

Thiocyanate overload does not play a role in high prevalence of goiter in the studied population. We suggest the role of other goitrogenic factors should be investigated in this region.

Endemic goiter in Semirom; there is no difference in vitamin A status between goitrous and nongoitrous children

BACKGROUND

Despite long-standing iodine supplementation in Iran, the prevalence of goiter remains high in some areas. This suggests other nutritional deficiencies may be considered as responsible factors for goiter persistence. In the present study we investigated the possible role of vitamin A deficiency (VAD) and low vitamin A status in the etiology of endemic goiter in Semirom, Iran.

MATERIALS AND METHODS

In this cross-sectional study, 1,828 students from 108 primary schools of urban and rural areas of Semirom were selected by multistage random cluster sampling. Thyroid size was estimated in each child by inspection and palpation. Urinary iodine concentration (UIC) and serum retinol (SR) were measured.

RESULTS

Overall, 36.7% of schoolchildren had goiter. The median UIC was 18.5 microg/dL. The mean+/-SD of SR in goitrous and nongoitrous children was 38.84+/- 10.98 and 39.17+/-10.85 microg/dL respectively (p=0.82). There were two children with VAD (SR less than 20 microg/dL); one in the goitrous and one in the nongoitrous group. The prevalence of subjects with low vitamin A status (SR less than 30 microg/dL) in the goitrous and nongoitrous groups was 26.2 and 21.5% respectively (p=0.42).

CONCLUSION

Goiter is still a public health problem in this region. Iodine deficiency, VAD or low vitamin A status is not among the contributors of goiter persistence in schoolchildren of Semirom. The role of other micronutrient deficiencies or goitrogens should be investigated.

Selenium deficiency as a possible contributor of goiter in schoolchildren of Isfahan, Iran

The prevalence of goiter still remains high in some areas of Iran in spite of iodine supplementation. In the present study, we investigated the role of selenium (Se) deficiency in the etiology of goiter in Isfahan. Two thousand three hundred thirty-one schoolchildren were selected by multistage random sampling. Thyroid size was estimated in each child by inspection and palpation. Urinary iodine concentration (UIC) and plasma Se were measured. Overall, 32.9% of the 2,331 children had goiter. The median UIC was 19.55 microg/dl. Plasma Se was measured in 96 goitrous and 72 nongoitrous children. The mean +/- SD of plasma Se in goitrous and nongoitrous children was 66.86 +/- 21.82 and 76.67 +/- 23.33 microg/l, respectively (P = 0.006). Goitrous girls had lower plasma Se level than nongoitrous girls (65.62 +/- 21.64 vs. 76.51 +/- 22.61 microg/dl, P = 0.02). Goitrous boys had lower plasma Se level than nongoitrous boys (68.45 +/- 22.21 vs. 76.91 +/- 24.76 microg/l, P = 0.14). The prevalence of Se deficiency was significantly higher in goitrous boys and girls than nongoitrous children. Se deficiency is among the contributors of goiter in Isfahan goitrous schoolchildren. However, the role of other micronutrient deficiencies or goitrogens should be investigated in this region.

Vitamin A status does not contribute to the residual goiter in schoolchildren of Isfahan, an iodine replenished area

Two thousand three hundred and thirty-one schoolchildren were selected by multi-stage random sampling. The thyroid size was estimated by inspection and palpation. The urinary iodine concentration and serum retinol (SR) were measured in 454 and 468 schoolchildren, respectively. Overall, 32.9% of 2,331 children had goiter. The median urinary iodine concentration was 195.5 microg/l. The mean+/-standard deviation of SR in goitrous and non-goitrous children was 34.84+/-7.28 microg/dl and 33.73+/-7.87 microg/dl, respectively (P=0.14). There was no child with vitamin A deficiency (SR <20 microg/dl) in both the goitrous and non-goitrous groups. The prevalence of subjects with low vitamin A status (SR <30 microg/dl) in the goitrous and non-goitrous groups was 27.7% and 33.3%, respectively (P=0.21). In conclusion, the present study reveals that vitamin A deficiency and low vitamin A status are not among the contributing factors of goiter persistence in the studied area, and the role of other responsible factors should be investigated.

Sustainability of a well-monitored salt iodization program in Iran: marked reduction in goiter prevalence and eventual normalization of urinary iodine concentrations without alteration in iodine content of salt

OBJECTIVE

Two yr after legislation of salt iodization of 40 parts per million (ppm) in 1994, goiter was still endemic and urinary iodine concentration (UIC) remained elevated in many provinces of Iran. Goiter prevalence and UIC were compared 2 and 7 yr after sustained consumption of uniformly iodized salt by Iranian households.

METHODS

Schoolchildren (7-10 yr) of all provinces were randomly selected by cluster sampling from December 2000 to June 2001. Goiter rate, UIC, and household salt iodine values were compared to those in 1996. Factory salt iodine was also compared in 2001 vs 1996. Ultrasonographically determined thyroid volumes of 7-10 yr old children were compared in 2001 vs 1999.

RESULTS

In 2001 (no.=33600) vs 1996 (no.=36178), total, grade 1, and grade 2 goiter rates were 13.9 vs 53.8%, 11.0 vs 44.8%, and 2.9 vs 9.0%, respectively (p<0.0001). Weighted total goiter rate was 9.8% in 2001. Median (range) UIC in 2001 (no.=3329) was 165 (18-499) microg/l and in 1996 (no.=2917) was 205 (10-2300) microg/l (p<0.0001). In 2001 vs 1996, mean+/-SD for iodine salt content was 32.7+/-10.1 vs 33.0+/-10.2 ppm (p=0.68) in households and was 33.2+/-13.4 and 33.8+/-13.2 ppm (p=0.57) in factories, respectively. Among 7-10 yr old children in 2001 (no.=400) vs 1999 (no.=396), only 7-yr-old children in 2001 (the only group with probably no history of iodine deficiency) showed significant smaller thyroid volumes by ultrasonography compared to those in 1999.

CONCLUSIONS

After 7 yr of optimized iodized-salt supplementation in Iran, adequate UIC values and marked reduction in goiter rate have been achieved.

Assessment of intertrimester and seasonal variations of urinary iodine concentration during pregnancy in an iodine-replete area

OBJECTIVE

To assess intertrimester and seasonal variations in urinary iodine concentration (UIC) among pregnant women.

PATIENTS AND MEASUREMENTS

Pregnant Tehranian women, with no history of thyroid ablation or consumption of thyroid-affecting medication were selected consecutively from November 2004 to November 2006. Morning spot urine samples were collected from each participant during the first, second and third trimesters of pregnancy. Of 466 participants, 298 completed the study in all three trimesters of pregnancy. UIC < 150, 150-250, and > 250 microg/l indicated low, adequate, and high levels, respectively. UIC was measured using a modified Sandell-Kolthoff digestion method.

RESULTS

The pregnant women were aged 25.0 +/- 5.0 (range 16-48) years. Median UIC did not show seasonal fluctuations during pregnancy. However, median (range) UIC was 193 (19-840), 159 (16-640), and 141 (16-400) microg/l in the first, second and third trimesters of pregnancy, respectively (P < 0.0001). Frequency distributions of low, adequate and excessive UIC were 33.2, 31.2 and 35.6% in the first trimester, 46.0, 28.9 and 25.2% in the second trimester, and 53.4, 30.9 and 15.8% in the third trimester of pregnancy, respectively (P < 0.0001). Women with UIC < 150 were more frequently represented in the second vs. the first (P = 0.043; odds ratio 1.49, 95% confidence interval 1.012-2.213) and in the third vs. the first (P = 0.013; odds ratio 1.62, 95% confidence interval 1.108-2.379) trimesters of pregnancy than the 150-250 microg/l group were. UIC decreased throughout pregnancy in all seasons.

CONCLUSIONS

Iranian national salt iodization may prevent seasonal fluctuations of UIC but does not maintain median UIC within adequate and recommended ranges throughout pregnancy. Extra iodine supplementation during pregnancy is recommended.

A survey of urinary iodine concentration in south-east of Caspian Sea in northern, Iran

The objective of this study was to evaluate the urinary iodine concentration in Gorgan located in northern Iran, which is a cosmopolitan society and on the basis of such determination the endemic goiter in the region could be estimated. The sample population were a total of 287 people (23.3% male, 76.7% female) referred to Danesh Medical Diagnostic Laboratory for the urinary iodine measurement, during 2004-05. Urinary iodine level was determined using acid digestion method. The results from this study indicated that 2.1, 3.8 and 9.8% of sample population had urinary iodine level of <2, 2-4.9 and 5-9.9 microg dL(-1), respectively which are defined as sever, moderate and mild iodine deficiency. Therefore 45 (15.7%) of the sample population in this study could be assessed for goiter prevalence, the mean differences of iodine concentration in male and female subjects were not significant. In conclusion, low urinary iodine of <10 microg dL(-1) concentration may help to give a direction for a further examination in the thyroid gland abnormalities.

Goiter rate, serum thyrotropin, thyroid autoantibodies and urinary iodine concentration in Tehranian adults before and after national salt iodization

Goiter rate, serum TSH, antithyroperoxidase (TPOAb), antithyroglobulin (TgAb) antibodies, and urinary iodine concentration (UIC) were evaluated 10-11 yr prior (1983-1984) and 5-6 yr after (1999-2000) national salt iodization in Iran. Pre- and post-iodization groups consisted of 465 and 1426 adults aged > or =20 yr, respectively, selected by random cluster sampling in Tehran province. Total, grade 1 and grade 2 goiter rates were 65.2, 53.1, and 12.1% in 1983-1984 vs 25.2, 15.5, and 9.7% in 1999-2000 (p<0.0001). Median serum TSH was 1.5 mIU/l in 1983-1984 vs 0.8 mIU/l in 1999-2000 (p<0.0001). Median TSH also decreased in 20-29, 30-39, 40-49, 50-59, and > or =60- yr-adults in 1983-1984 vs 1999-2000 (p<0.0001). In 1983-1984, positive TPOAb and positive TgAb were detected in 3.2 and 4%, respectively, using agglutination test. Corresponding values were 12.5 and 16.8% using immunoenzymometric assay in 1999-2000. Overt and subclinical hypothyroidism was present in 0 and 32.8/1000 in 1983-1984 vs 3.5 and 21.7/1000 in 1999-2000, respectively. Overt and subclinical hyperthyroidism was detected in 4.4 and 4.4/1000 in 1983-1984 vs 0.7 and 5.6/1000 in 1999-2000, respectively. Subclinical hypothyroidism in males was significantly more frequent in 1983-1984 vs 1999-2000 (odds ratio 5.02, 95% confidence interval 1.72-14.68; p=0.004). Salt iodization resulted in adequate UIC, decrease in serum TSH and subclinical hypothyroidism in males, and an increase in thyroid autoantibodies without significant change in thyroid abnormalities. Benefits of iodine supplementation far outweigh its hazards in Tehranian adults.

Risk factors for goiter in primary school girls in Qom city of Iran

OBJECTIVE

Goiter is endemic in Iran. The iodine deficiency disorders program was begun a few years ago in Iran, and the coverage of iodized salt is sufficient now. But, in a periodic yearly medical examination of primary school girls in Qom, the prevalence of goiter was above 30% in 2002. This survey was designed to study the risk factors of goiter in those students.

DESIGN

The study was a randomized (multistage, proportional simple random sampling) case-control study.

SUBJECTS AND INTERVENTIONS

We selected and performed thyroid examinations in 1050 girl students in primary schools in Qom city of Iran in 2002. We found 284 cases: girls in primary schools had goiter in accordance with the clinical exam of World Health Organization classification. Among students who did not present with goiter in the clinical exam, we randomly selected 288 students as the control group. We used a questionnaire to evaluate them for the risk factors of goiter.

RESULTS

The mean+/-s.d. ages of cases and controls were 8.7+/-1.3 and 8.9+/-1.3 years, respectively. There is no significant difference between the two groups regarding history of soya, kale, turnip, fish, daily iodized salt usage, education and job of mothers, monthly family income, nationality, immigration and residential situation. By using multinomial logistic regression, we found that storage of iodized salt in open containers, odds ratio (OR): 2.201 (1.412-3.428); P-value <0.0001, medium socioeconomic situation (SES) of family, OR: 2.099 (1.029-4.282), P-value=0.041, district 2 of Qom city, OR: 2.880 (1.376-6.027), P-value=0.005, and district 3 of Qom city, OR: 2.051(1.032-4.078), P-value=0.041, were the major risk factors for goiter in this population.

CONCLUSIONS

In this study, the main risk factors for goiter were storage of iodized salt in open containers, medium SES and also living in specific districts of Qom city. As the coverage of iodinized salt is over 95% in Iran, we advise the education of the family about storage of iodized salt in closed containers. We also recommend the study of the other risk factors of goiter in the different geographical areas of Iran, because of differences in the SES and nutritional habits.

SPONSORSHIP

This study was supported by issuing permission letters for our activities: (not funding support) Qom Health Network and Medical Services, Qom Medical University, Qom Primary School Education Office, Fathemieh Medical University.

Prevalence of goiter among schoolchildren from Gorgan, Iran, a decade after national iodine supplementation: association with age, gender, and thyroperoxidase antibodies

BACKGROUND

One decade after universal salt iodization in Iran, goiter prevalence, urinary iodine concentration (UIC) and thyroperoxidase antibody (TPOAb) values were assessed among schoolchildren in Gorgan, Iran.

METHODS

From 2003-2004, 500 girls and 900 boys aged 7-11 yr were evaluated for goiter by palpation. UIC was measured in 183 randomly-selected goitrous children. Serum TSH, T4, and TPOAb were measured in 53 goitrous and 30 non-goitrous children with adequate UIC.

RESULTS

Goiter was detected in 370 (26.4%) children. Goiter was present in 31% of girls and 17% of boys age 9 (p<0.012); 37% of girls and 20% of boys age 10 (p<0.003); and 52% of girls and 19% of boys age 11 (p<0.0001). Median (range) UIC for all goitrous children sampled was 190 (20-600) microg/l; 220 (30590) in boys and 170 (20-600) in girls (p=0.001). Eight point seven percent of goitrous children and 22% of goitrous girls aged 10-11 had UIC<100 microg/l, while 47% of the goitrous children had UIC> or =200 microg/ l. TPOAb was present in 52.8% of goitrous children and 10% of non-goitrous children (p=0.0001). TPOAb was present in 53.9% of 10-11 and 22.7% of 7-9 yr old goitrous and non-goitrous children (p=0.003) with adequate UIC. Median (range) TSH was 2.9 (0.3-10.9) mlU/I in TPO-positive and 1.8 (0.5-4.1) in TPO-negative children (p=0.001).

CONCLUSIONS

Gorgan, Iran, is an iodine-sufficient area and almost half of schoolchildren have more than adequate UIC. TPOAb is associated with endemic goiter. Despite sufficient UIC overall, some school-aged girls remain at risk of iodine deficiency.

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.

Effects of levothyroxine suppressive therapy on bone mineral density in premenopausal women

BACKGROUND

Levothyroxine (L-T4) is widely prescribed for treating thyroid disorders, but its effect on bone mineral density (BMD), is being debated.

OBJECTIVES

We studied the effect of supraphysiologic doses of L-T4 on BMD in a group of premenopausal women.

PATIENTS AND METHODS

We included 50 women (mean age=36.8 +/- 7.6 years) receiving L-T4 for at least 1 year for treating their benign cold thyroid nodules. Serum T3, T4, thyroid-stimulating hormone (TSH), parathyroid hormone (PTH), calcium, and phosphate and urine calcium and sodium levels of all patients were measured. Bone density at femoral neck and lumbar (L1-L4) regions was measured, using dual energy X-ray absorptiometry (DXA).

RESULTS

No significant decrease was detected in the bone density of the subjects treated with L-T4 compared with the control group.

CONCLUSION

L-T4 treatment for 1 year is not associated with increased risk of osteoporosis in premenopausal women but other potential adverse effects still need to be monitored in women receiving L-T4 especially long-term.

Comparison of Urinary Iodine Excretion in Neonates and Their Mothers in Isfahan, Iran

OBJECTIVE

To determine the urinary iodine excretion of neonates (28 days of age or younger) and their mothers in Isfahan, a centrally located city in Iran, in 1997 after 8 years of iodized salt distribution in an effort to ameliorate iodine deficiency.

METHODS

Through a cross-sectional study and by means of convenient sampling, 146 mother-neonate pairs were selected among neonates born in Shahid Sadoughi Hospital in Isfahan. In order to eliminate the effect of povidone-iodine on breast milk and urinary iodine, Savlon antiseptic solution was used in normal vaginal delivery and on the umbilical cord. Normal values of urinary iodine concentration for the mothers and their neonates were > or = 10.0 microg/dL and >5.0 microg/dL, respectively. The data were analyzed and compared by the Student t test and Pearson correlation coefficient in SPSS software. P values <0.05 were considered statistically significant.

RESULTS

In only 3% of the neonates and 14% of the mothers, urinary iodine excretion was below the normal range. No mother or neonate had severe iodine deficiency. In 2% of the mothers and 2% of the neonates, mild iodine deficiency was found. The mean urinary iodine concentration of neonates whose mothers were iodine deficient was significantly lower than that of neonates whose mothers were iodine sufficient (17.34 +/- 7.83 microg/dL versus 22.21 +/- 7.57 microg/dL; P<0.01). A direct significant correlation was noted between the urinary iodine excretion of neonates and that of their mothers (r = 0.37; P<0.01).

CONCLUSION

The urinary iodine excretion in mothers paralleled the urinary iodine concentration of their neonates. If urinary iodine concentration is considered an index of total body iodine content, this study demonstrated that prolonged iodized salt intake has minimized the occurrence of iodine deficiency in Isfahan.

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.

Thyroid size and iodine intake in iodine-repleted pregnant women in Isfahan, Iran

OBJECTIVE

To evaluate the goiter and iodine intake status of pregnant women in Isfahan, after 8 years of iodized salt distribution in Iran.

METHODS

Thyroid staging was assessed by clinical examination, thyroid volume was determined by sonography, and urinary iodine (UI) excretion was assessed by the digestion method in 90 healthy pregnant women (30 in each trimester) and 90 age-matched nonpregnant women selected by random sampling in prenatal and primary health-care clinics. The data were reported as mean +/- standard deviation; P values <0.05 were considered statistically significant.

RESULTS

The mean age of the pregnant and the nonpregnant women was 25.3 and 27.5 years, respectively-no significant difference (P = NS). The clinical goiter prevalence in the pregnant and the nonpregnant groups was 37% and 32%, respectively (P = NS). The mean thyroid volume in the pregnant and nonpregnant women was 7.8 +/- 3.2 and 7.8 +/- 2.8 mL, respectively (P = NS). Urinary iodine (UI) excretion was 20.7 +/- 6.9 mg/dL in pregnant women and 23.7 +/- 7.6 mg/dL in nonpregnant women (P = NS). The prevalence of goiter assessed by sonography was 29% in pregnant women and 21% in nonpregnant women (P = NS). The mean thyroid size in 26 of 90 pregnant women with goiter (thyroid volume >9.2 mL) was 11.8 +/- 2.73 mL and in 19 of 90 nonpregnant women with goiter was 12.36 +/- 1.6 mL (P = NS). The mean thyroid volume was 6.0 +/- 1.7, 9.9 +/- 1.7, 11.8 +/- 2.2, and 18.9 +/- 2.4 mL in the pregnant women with or without goiter at thyroid stages 0, Ia, Ib, and II, respectively. A strong correlation between goiter staging assessed by clinical examination and thyroid volume determined by sonography was found in pregnant (r = 0.77) and nonpregnant (r = 0.78) women (both P<0.000001). Mean UI excretion was 20.9 +/- 7.0, 19.9 +/- 6.8, 20.6 +/- 7.5, and 25.9 +/- 2.3 mg/dL in the pregnant women at thyroid stages 0, Ia, Ib, and II, respectively. In the pregnant and the nonpregnant women, no correlation was found between thyroid stage and UI excretion or between thyroid volume and UI excretion.

CONCLUSION

No iodine deficiency was found in Isfahani pregnant women. Thus, as in most iodine-sufficient areas, thyroid size did not increase during pregnancy. Despite sufficient iodine intake, a moderate prevalence of goiter was noted in pregnant and nonpregnant women. This study also revealed that careful physical examination of the thyroid had diagnostic accuracy similar to sonography.

Effects of iodized salt consumption on goiter prevalence in Isfahan: the possible role of goitrogens

OBJECTIVE

To evaluate the success of the Iranian Iodine Deficiency Disorders Committee in achieving World Health Organization (WHO) goals for reducing the prevalence of goiter in children by adding iodine to table salt beginning in 1989.

METHODS

In 1997, 8,000 male and female 6- to 18-year-old students were selected by cluster sampling in schools of Isfahan. Their thyroids were examined by four endocrinologists, and goiter was staged on the basis of the WHO classification. As an index of iodine consumption, urinary iodine concentrations were measured in 3,000 students.

RESULTS

Goiter was observed in 62% of the students. Of the overall study group, 94% had sufficient iodine consumption (urinary iodine concentration of 10.0 microg/dL or more). Of those students who had sufficient iodine intake, 63.2% had goiter. Of the 6% of students with iodine deficiency, 5% had mild, 0.9% had moderate, and only 0.1% had severe iodine deficiency. Goiter was absent in half of the students with severe iodine deficiency. The prevalence of goiter in 6- to 10-year-old children was 65%.

CONCLUSION

Despite sufficient iodine intake, the prevalence of goiter is still high in Isfahan City. Apparently, either this high prevalence has no relationship to iodine deficiency and possibly other unknown goitrogens are involved in the pathogenesis of goiter in Isfahan or the period of iodine intake has been too brief to affect thyroid sizes. Inasmuch as goiter prevalence is also high in the 6- to 10-year-old children, who have had iodized salt available for most of their lives, the second option is less probable. Another possibility is an increased rate of autoimmune thyroid diseases (because of iodine repletion) that resemble goiter during their early stages.