Iodine supplementation for pregnant women: a cross-sectional national interventional study

BACKGROUND

Although Iran has been considered iodine replete since 2000, the first national survey of iodine intake among Iranian pregnant women in 2014 indicated that despite the adequate intake of iodine by the general population, this vulnerable group has moderate iodine deficiency. Therefore, in this national cross-sectional interventional study, we aimed to assess the iodine intake and thyroid function of Iranian pregnant women 2 years after implementing national iodine supplementation for this vulnerable group.

MATERIALS AND METHODS

In this cross-sectional study, we conducted a national interventional survey of pregnant women. A total of 1200 pregnant women (400 women from each trimester) from 12 provinces of Iran were recruited from the antenatal care clinics from October 2018 to March 2019. The median urinary iodine concentration (MUIC), as an indicator of iodine status in three spot urine samples, was measured, along with the serum total T4 (TT4), thyrotropin (TSH), thyroglobulin (Tg), thyroid peroxidase antibody (TPO-Ab), and iodine content of household salt.

RESULTS

The mean age of the cohort was 28 ± 6.2 years, with the mean gestational age of 22.7 ± 13.0 weeks. The overall MUIC (IQR) of pregnant women was 188 µg/L (124.2-263 µg/L). Also, the MUICs in the three trimesters of pregnancy were 174 µg/L (110-254), 175 µg/L (116-251), and 165 µg/L (114-235), respectively. The MUICs ≥ 150, 100-149, and < 100 µg/L were found in 63, 19.8, and 16.2% of the subjects, respectively. The mean TT4 level was 12 ± 4.5 µg/dL, and the median (IQR) level of TSH was 2.37 mIU/L (1.66-3.18 mIU/L). According to our local reference range, 118 (10.5%) pregnant women had subclinical hypothyroidism, 6 (0.53%) women had isolated hypothyroxinemia, and 65 (5.7%) women were TPO-Ab positive. Also, the median (IQR) level of Tg was 10.08 µg/dL (5.7-20.4 µg/dL), and the median iodine content of household salt was 29.6 µg/g; the iodine content was ≥ 30 µg/g in 85% of household salt. The results showed that more than 95% of households were under iodized salt coverage.

CONCLUSION

The results of this study indicated that iodine supplementation with at least 150 µg of iodine per day improved the iodine intake of pregnant women. Except for subclinical hypothyroidism, the prevalence of clinical hypothyroidism, clinical/subclinical thyrotoxicosis, TPO-Ab positivity, and isolated hypothyroxinemia decreased significantly, which emphasizes the importance of iodine supplementation during pregnancy.

The Relationship Between Delivery Mode and Cord Blood Betaendorphins Values in the Newborns of Nulliparous Women

Background & Aims of the Study: Beta-Endorphin (β-EP), as the main stress hormone, is secreted during delivery and labor and modifies the pain threshold and sensation. This study aimed to determine the umbilical cord blood level of β-EP and its related factors in two groups of nulliparous women with Natural Vaginal Delivery (NVD) and Elective Cesarean Section (ECS). Materials and Methods: This case-control study was conducted on 80 pregnant women (40 cases & 40 control) at 38-42 weeks of gestation. Besides, the study subjects presented no history of chronic diseases, pregnancy complications, abortion, stillbirth, or infertility. The explored cases were women with NVD and the control were women with ECS. After delivery, a 3-mL blood sample was collected from the placental umbilical cord. After separating the blood serum, the β-EP level was examined using a standardized β-EP kit (Glory Co., USA). Data analysis was performed in SPSS using the Chi-squared test, t-test, and Fisher’s Exact test (P≤0.05). Results: The study groups were matched on individual, social, and obstetric characteristics, such as age, educational level, occupational status, gestational age, body mass index, and the frequency of prenatal care. The obtained results indicated that the umbilical cord blood levels of β-EP were significantly higher in the NVD group, compared to the ECS group (P=0.03). Conclusion: The present research results suggested that NVD provides greater effects on the release of β-EP, in comparison with ECS.

Iodine nutrition in pregnant and breastfeeding women: sufficiency, deficiency, and supplementation

Iodine is a micronutrient used by the thyroid gland to produce thyroid hormones, which manage different aspects of body metabolism. Humans depend on exogenous sources of iodine to maintain the normal concentration of thyroid hormones. Pregnancy alters iodine turnover and is associated with significant changes in thyroid function. Daily iodine requirement during pregnancy increases to 250 μg, compared with 150 μg for nonpregnant women. According to recent guidelines of scientific organizations, to improve maternal thyroid status and to prevent child neurocognitive defects, all pregnant and breastfeeding women should take 150 μg of iodine supplementation, not only in iodine-deficient regions but also in iodine-sufficient areas. However, some recent studies have confirmed that iodine supplementation of mildly iodine-deficient pregnant women has no clear benefits as concerns maternal thyroid function or child neurodevelopment.

Isolated Hypothyroxinemia in Iranian Pregnant Women, the Role of Iodine Deficiency: A Population-Based Cross-Sectional Study

Background: Thyroid disorders such as subclinical hypothyroidism and isolated maternal hypothyroxinemia are understudied in pregnant women, despite their possible adverse effects on the health of mother and child. Also, the role of iodine deficiency in developing such disorders has not yet been fully understood. Methods: The present national population-based cross-sectional study was conducted on 1080 randomly recruited pregnant women, aged 20-40 from 12 provinces of Iran from 2013 to 2014. Serum concentrations of thyrotropin, T4, thyroid peroxidase antibody (TPOAb), and triiodothyronine (T3) resin uptake values were measured in fasting blood samples, and urinary iodine concentration (UIC) was measured in three separate urine samples. Multinomial logistic regression was run to analyze the possible risk factors regarding thyroid disorders. To clarify the role of iodine in thyroid status specifically, the determinants of UIC and its correlations with thyroid function tests were investigated independently and through subgroup analysis. Results: Isolated hypothyroxinemia was the most common thyroid disorder (9.9%), followed by subclinical hypothyroidism (8%). In comparison to euthyroid pregnant women, isolated hypothyroxinemia was more likely in pregnant women older than 30 years (odds ratio [OR] = 1.6), in the second and the third trimesters (OR = 2.62 and 2.12 respectively), with history of multiparity (OR = 1.72), residing in rural areas (OR = 1.57) and in the capital province of the country (OR = 3.3). Subclinical hypothyroidism was more likely in TPOAb positive pregnant women (OR = 2.56). All the mentioned ORs were statistically significant (p < 0.05). The UIC did not correlate significantly with any of the thyroid function tests in the study population. Subgroup analysis showed a significant correlation between UIC and T4 in pregnant women with subclinical hypothyroidism (p < 0.05). Conclusion: Isolated maternal hypothyroxinemia was the most prevalent thyroid disorder in Iranian pregnant women and its associated risk factors were identified. Although the calculated prevalence of thyroid disorders was expected in a moderately iodine deficient setting, no correlations between UICs and thyroid function tests were found at the individual level. The contribution of iodine deficiency to thyroid condition for each pregnant woman may be more evident in pregnant women with certain thyroid disorders or those with long-term iodine deficiency.

Trend of lipid and thyroid function tests in adults without overt thyroid diseases: A cohort from Tehran thyroid study

Context

While the role of overt hypothyroidism in lipid disorders is clear, the association between dyslipidemia and subclinical thyroid diseases remains unclarified.

Objective

To examine lipid trends based on thyroid function over a 10-year period.

Design

This is a prospective population based cohort study.

Setting

General community.

Participants

2383 euthyroid participants, as well as those with subclinical thyroid diseases, in all residents of district 13 of Tehran were examined. Subjects who were on levothyroxine, anti-hyperthyroid drugs, and glucocorticoids, those with a history of thyroid surgery or RAI and pregnant women were excluded.

Main outcome measures

Lipid trends in Model 1 were adjusted for age and follow up duration, and in Model 2 gender-specific multivariate adjustments were performed for thyroid status, diabetes mellitus, smoking status, education, BMI, lipid lowering medications, age and follow up duration by using generalized estimating equations.

Results

In every four years of assessments, there were significant decreases in levels of all lipid parameters (all Ps <0.001) except for HDL-C, in which a decrescendo-crescendo trend was observed. The results did not change after adjusting for thyroid status, consumption of lipid lowering drugs during the follow-up period, or other variables. There were significant decreases in the prevalence of hypercholesterolemia and hypertriglyceridemia (all Ps <0.001) during the follow-up period.

Conclusion

During a 10 year follow-up, decrescendo trends were observed in levels of total cholesterol, triglycerides, which were not be accounted for by the consumption of lipid lowering drugs and thyroid status.

Evaluation of the congenital hypothyroidism screening programme in Iran: a 3-year retrospective cohort study

OBJECTIVE

To evaluate the newborn screening programme for congenital hypothyroidism (CH) in Iran from diagnosis to management and follow-up for 3 years from 2011 to 2014.

DESIGN

Retrospective cohort.

SETTING AND PATIENTS

Seventeen university districts were randomly selected from 30 provinces. Central data in each district were gathered and collectively analysed. Congenital hypothyroid subjects were followed for 3 years.

MAIN OUTCOME MEASURES

Programme coverage, screening and treatment age, recall rate, compliance to follow-ups.

RESULTS

The total number of births in 2011 was 501 726, of which 452 918 neonates (90.3%) were screened and 15 671 (3.46%) were recalled; 1085 (1:462, 0.22%) were confirmed as having CH (57.1%: permanent, 42.9%: transient) and followed for 3 years. Positive predictive value (PPV) for the first screening test was 6.9%. After the second screening, recall rate was reduced to 0.69% and PPV increased to 31.3%. Median age at screening was 6 (3-9) days and for 90.6% of patients treatment was initiated before 40 days of age with a median levothyroxine dosage of 25 µg/day; 131 (13.4%) were lost to follow-up. Mean number of follow-up visits over 3 years was 5.7 (95% CI 5.5 to 5.9) and 23% (n=225) had total compliance to all follow-ups. Median time for thyroid stimulating hormone normalisation was 45 days, 95% CI (41.1 to 48.8).

CONCLUSION

In Iran, despite well-established protocols of screening and detecting CH subjects, stricter implementation of a structured system for monitoring and surveillance is needed to promote the management of patients and to reduce rates of loss to follow-up. Determining and addressing the causes of high false positive rates must be prioritised.

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.

Secondary and tertiary preventions of thyroid disease

INTRODUCTION

Secondary and tertiary preventions are concerned with the recognition of the disease process in a very early stage and delay in progression to complete disease and minimization of complications and the impact of illness.

METHODS

All articles related to secondary and tertiary prevention of thyroid diseases were reviewed. Using related key words, articles published between 2001 and 2015 were evaluated, categorized, and analyzed.

RESULTS

In secondary prevention, congenital hypothyroidism and subclinical hypo and hyperthyroidism are equally important. Routine screening of patients with multinodular goiter by either ultrasonography or calcitonin is a controversial issue, while calcitonin assessments in medullary cancer and RET in family members are recommended. Screening of thyroid disease in pregnancy is limited to those with risk factors. Views regarding the importance of thyroid autoimmunity in secondary prevention are also presented. In tertiary prevention, prescribing excessive doses of levothyroxine, in the elderly in particular and appropriate care of all patients to avoid progression and complications are the key issues.

CONCLUSION

Optimization of management of thyroid diseases requires timely screening, prevention of progression to more sever disease, optimal medical care, and avoidance of iatrogenic conditions.

The Impact of Iodine Status on the Recall Rate of the Screening Program for Congenital Hypothyroidism: Findings from Two National Studies in Iran

Back ground: Iodine deficiency is one of the important factors in increasing the recall rate in congenital hypothyroidism (CH) screening programs. The present study assessed whether the iodine status of the general population may predict the recall rate or vice versa.

METHODS

In the current national study, among 1,382,229 live births delivered between March 2010 and March 2011, 1,288,237 neonates were screened for detecting CH by TSH (thyroid stimulating hormone) measurement via heel prick sampling. Simultaneously, a total of 11,280 school-aged children, aged 7-8 years, were selected using random multi-cluster sampling for measurement of urinary iodine.

RESULTS

A negative correlation was found between median urinary iodine (MUI) and the recall rate (r = -0.33, p = 0.03). No correlation was found between MUIC (median urinary iodine concentration) and the incidence rate of CH. Linear regression analysis showed a 0.1% increase in the recall rate for a one unit decrease in MUIC (β = -0.11, 95% CI: -0.2, -0.1, p = 0.03). MUIC, at a cut-off point of 144.7 µg/L, was predictive for a recall rate < 3% (p = 0.05).

CONCLUSION

Frequencies of TSH ≥ 5 mU/L may be a more sensitive indicator for iodine status during pregnancy rather than in the general population. As higher recall rates reflect inadequate iodine nutrition, sufficient iodine supplementation is needed to reduce the recall rate in such communities.

Primordial and Primary Preventions of Thyroid Disease

BACKGROUND

Primordial and primary preventions of thyroid diseases are concerned with avoiding the appearance of risk factors, delaying the progression to overt disease, and minimizing the impact of illness.

SUMMARY

Using related key words, 446 articles related to primordial and primary, preventions of thyroid diseases published between 2001-2015 were evaluated, categorized and analyzed. Prevention and elimination of iodine deficiency are major steps that have been successfully achieved and maintained in many countries of the world in last 2 decades. Recent investigations related to the effect of cigarette smoking, alcohol consumption, and autoimmunity in the prevention of thyroid disorders have been reviewed.

CONCLUSIONS

The cornerstone for successful prevention of thyroid disease entails timely implementation of its primordial and primary preventions, which must be highly prioritized in related health strategies by health authorities.

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.

The Association Between Normal Range TSH and Lipid Profile

Dyslipidemia in thyroid dysfunction is mostly attributed to thyrotropin (TSH) levels, especially in subclinical disorders, but the exact role of TSH in dyslipidemia has not been explained. A total of 3 020 subjects who remained euthyroid in 3 phases of the Tehran Thyroid study were enrolled and divided according to quartiles of TSH as: Q1 (0.32-1.02), Q2 (1.02-1.53), Q3 (1.53-2.27), and Q4 (2.27-5.06). General Linear model was used to determine whether there was a significant correlation between subjects' lipid profile and quartiles of TSH from 1st to 2nd and from 1st to 3rd phase. Mean TC, LDL-C level and median TG were significantly higher for Q1 in all study phases. All lipid parameters of participants after 6 years (3rd phase study) except LDL-C were significantly varied in different TSH groups. Highest levels of TC, TG and HDL-C were observed in Q4. Thus, irrespective of TC and LDL-C in Q1 and Q4 (participants with the lowest and highest limit of TSH within the normal range), the difference in lipid parameters in middle of normal TSH range was not significant. Normal range TSH levels have a statistically significant effect on lipid profile, but the effect size is not clinically significant.

The Effects of Iodine Fortified Milk on the Iodine Status of Lactating Mothers and Infants in an Area with a Successful Salt Iodization Program: A Randomized Controlled Trial

Iodine deficiency during the first two years of life may cause irreversible brain damage and mental retardation. The aim of the present study was to investigate, for the first time, the effect of iodine fortified milk on the iodine status of lactating mothers and their infants. In this multicenter randomized controlled trial, 84 lactating mother-infant pairs from health care centers were randomly selected. After meeting the inclusion criteria, lactating mothers were randomly assigned to two groups: the iodine fortified milk group and the control group (n = 42 each). Maternal and infant urine and breast milk samples were collected at 3–5 (baseline), 7, 10, 14 days, and 1 month postpartum, for a measurement of the iodine concentration. A total of 84 lactating mothers, with a mean age of 28.2 ± 4.5 years, and 84 infants, with a mean age of 4.2 ± 0.7 days, were included in the study. Compared to mothers of the control group, mothers receiving iodine fortified milk had higher urinary (p < 0.001) and breast milk (p < 0.001) iodine concentrations. Urinary iodine levels in infants revealed no significant differences between the two groups. The findings of this study indicate that supplementation with daily iodine fortified milk provides iodine nutrition adequacy among lactating mothers. However, it had no effect on the iodine status of infants, who were previously iodine sufficient.

Inadequate iodine nutrition of pregnant women in an area of iodine sufficiency

PURPOSE

I. R. Iran has been considered iodine replete since 2000, but iodine nutrition of vulnerable subjects is not clear. The main goal of this study was assessment of iodine nutrition and thyroid function in pregnant Iranian women.

METHODS

A total of 1072 pregnant women from ten provinces in the different parts of the country were recruited from November to March 2014. Median urinary iodine concentration (UIC) as the measure of iodine status and serum free T4 (FT4), thyrotropin (TSH), thyroglobulin (Tg), anti-thyroglobulin and anti-thyroid peroxidase antibodies (TgAb and TPOAb) were measured.

RESULTS

Mean ± SD age of the cohort was 27.0 ± 7.2 years and gestational age was 20.7 ± 10.0 weeks. The median UIC for pregnant women was 87.3 μg/L, being 92.1, 86.0 and 76.8 μg/L, in three trimesters of pregnancy, respectively. Median UIC of <100, 100-149, 150-249, 250-499 and ≥500 μg/L was found in 58.4, 19.8, 16.2, 5.13 and 0.46 % of subjects, respectively. Median (IQR) values in the first, second, and third trimesters were 1.7 (0.9-2.8), 2.1 (1.5-2.9), and 2.1 (1.4-2.8) mIU/L for TSH, and 16.4 (12.21-21.13), 14.34 (12.16-19.69), and 14/07 (12.02-18.64) pmol/L for FT4, respectively. The frequency of elevated serum TSH was 9.0 % (6.6 % subclinical, 2.4 % overt hypothyroidism). The frequency of low serum TSH was 0.6 %. The frequency of positive TPOAb was 7.6 %.

CONCLUSIONS

Results of this study have clarified that despite iodine sufficiency of school children in Iran, pregnant women have moderate iodine deficiency and need iodine supplementation.

Incidence and potential risk factors of obesity among Tehranian adults

AIM

Evaluating the incidence of obesity and its risk factors among Tehranian adults.

MATERIAL & METHODS

In this population-based cohort, non-obese participants, aged ≥20years, were followed for development of obesity (Body Mass Index (BMI) ≥30). Incidence density and cumulative incidence rates of obesity were calculated for each sex. Cox proportional hazard regression was used to determine the association of potential obesity risk factors including: age, BMI, metabolic syndrome, waist circumference (WC), smoking, marital status, education, and physical activity.

RESULT

A total of 7257 participants (3536 men) were followed for a median of 8years. At baseline, mean age, BMI and WC were 41.3±14.6years, 25.1±2.9kg/m(2) (24.9±3kg/m(2) men and 25.2±3kg/m(2) women), and 84.8±9.8cm (87.06±9.2cm men and 82.6±9.9cm women) respectively. During the follow-up, 1345 participants (876 women) developed obesity contributing to cumulative incidences of 31.3% (CI: 29.9%-32.7%), 38.1% (CI: 36.2%-40.1%), and 23.4% (CI: 21.6%-25.3%) for the whole population, women, and men, respectively. Corresponding incidence density rates per 1000 person-year were 25.9 (CI: 24.5-27.3), 33.67 (CI: 31.5-36.0), and 18.0 (CI: 16.5-19.7), respectively. Highest incidence rates were observed during their 40s and 20s for women and men, respectively. Participants with metabolic syndrome, lower educational level, higher BMI and WC, were at higher risk of obesity development in both sexes.

CONCLUSION

High incidence of obesity was observed among Tehranian adults with higher incidence of obesity in women. Different modifiable variables may act as risk factors for obesity development which should be targeted to control the epidemic of obesity.

Comparison of two guidelines on management of thyroid nodules and thyroid cancer during pregnancy

BACKGROUND

Some hormonal and metabolic changes may stimuli normal or neoplastic thyroid cells. Thyroid tumors discovered during pregnancy present unique challenges to both the clinician and the mother. The aim of this article is to compare American Thyroid Association (ATA) guidelines to Endocrine Society guidelines for management of thyroid tumors during pregnancy.

METHOD

We reviewed the section of thyroid nodules and cancer of ATA and Endocrine Society guidelines which have been published recently. Both organizations have discussed and given recommendations related to maternal and fetal aspects of thyroid nodules and cancer.  Each topic from either guidelines was compared together and that recommendation which was more complete included in 4 tables.

RESULTS

There is a high degree of similarity between these two guidelines. Both organizations have discussed and given recommendations related to maternal and fetal aspects of thyroid tumors. Regarding their similarity any of these two guidelines can be used for safe and proper management of women with thyroid tumors during pregnancy.

CONCLUSION

Regarding their similarity any of these two guidelines can be used by clinicians for safe and proper management of pregnant women with thyroid nodules and cancer.

White rice consumption is a risk factor for metabolic syndrome in Tehrani adults: a prospective approach in Tehran Lipid and Glucose Study

BACKGROUND

Consumption of white rice has been proposed as a dietary risk factor for development of metabolic disorders and type 2 diabetes, especially in populations who consume white rice as a staple food. In this study, we investigated the association between consumption of white rice and the occurrence of metabolic syndrome in Tehrani adults after 3 years of follow-up.

METHODS

This longitudinal study was conducted within the framework of the Tehran Lipid and Glucose Study on 1476 adults, aged 19-70 years. Dietary intakes were measured using a validated semi-quantitative food frequency questionnaire at baseline. Biochemical and anthropometric measurements were assessed and documented at baseline (2006-2008) and again 3 years later (2009-2011). Multiple logistic regression models were used to estimate the occurrence of the MetS in each quartile of white rice consumption.

RESULTS

The mean age of participants was 37.8 ± 12.3 years, and mean BMI was 26.0 ± 4.5 Kg/m2 at baseline. Participants in the highest quartile of white rice consumption were significantly younger, had lower HDL-C levels, and higher systolic and diastolic blood pressures at baseline (P < 0.01). Higher consumption of white rice was also accompanied by higher increase in serum triglyceride levels after the 3-year follow-up (9.9 ± 2.3 vs. 8.2 ± 2.3%, P < 0.01). After adjustment for all potential confounders, the risk of metabolic syndrome in the highest quartile of white rice consumption compared with the lowest, was 1.66 (95% CI: 1.04-2.66). Moreover, participants with central obesity, low physical activity or low-fiber diet had greater risk of metabolic syndrome if white rice constituted ≥25.6% of total energy.

CONCLUSION

We demonstrated that higher consumption of white rice may be a risk factor for development of metabolic syndrome among Iranian adults.

Alterations in food group intakes and subsequent weight changes in adults: tehran lipid and glucose study

BACKGROUND

The extent of weight change is varied for specific foods. This highlights the effect of dietary quality and food choices on weight control.

OBJECTIVES

The aim of this study was to examine the association between alterations in food group intake and weight change over a 3 years follow-up period.

MATERIALS AND METHODS

This longitudinal study was conducted on 851 adults in the framework of Tehran Lipid and Glucose Study. Intakes of various foods were measured at baseline and after 3 years using a validated semi-quantitative food frequency questionnaire. Dietary data was grouped into 13 food groups. Alterations in food group intakes were categorized in tertiles; middle tertile of intake changes was considered as the reference category and the first and last tertiles of changes as increased and decreased intakes, respectively. Weight change per year of follow-up was the outcome of interest. Weight gain was defined as ≥ 0.5 kg/y, weight loss as ≤ -0.5 kg/y and stable weight as > -0.5 to < 0.5 kg/y. Multinomial logistic regression was used with stable weight as the reference group.

RESULTS

IN MEN, WEIGHT LOSS WAS SIGNIFICANTLY PREDICTED ONLY BY DECREASED INTAKE OF ADDED SUGARS (OR: 2.21, 95% CI: 1.06-4.63). In women, weight gain was significantly predicted by decreased intake of whole grains (OR: 1.92, 95% CI: 1.11-3.31) and weight loss was predicted by decreased intake of vegetables (OR: 0.44, 95% CI: 0.21-0.91).

CONCLUSIONS

Alterations in consumption of whole grains, vegetables, and added sugars are associated with body weight change, suggesting that it could be helpful in weight control.

Reference limit of thyrotropin (TSH) and free thyroxine (FT4) in thyroperoxidase positive and negative subjects: a population based study

BACKGROUND

Current reference values for thyroid function tests are based on data from different ethnicities and geographical areas. The aim of the present study was to determine reference intervals for thyrotropin (TSH) and free T4 (FT4), based on the criteria of the National Academy of Clinical Biochemistry (NACB) in an Iranian population.

MATERIAL AND METHODS

This study was conducted within the framework of Tehran Thyroid Study (TTS), an ongoing prospective cohort of 5704 randomly selected individuals, age ≥ 20 yr. A total of 2199 individuals (43.3% male, 56.7% female), based on NACB criteria were included in this study. Reference limit analysis was performed for the negative thyroid peroxidase antibody (TPOAb) group.

RESULTS

After applying all exclusion criteria except TPOAb positivity (10.5%), data of 2459 participants remained for analysis. Of these, 953 (43.3%) were males and 1246 (56.7%) were females; the mean ± SD age was 43.53 ± 14.16 yr. The mean ± SD and median+IQR for TSH were 1.77 mU/l ± 1.24 and 1.46 (0.93-2.23) mU/l, respectively. The 2.5th and 97.5th percentiles TSH were 0.32 mU/l and 5.06 mU/l respectively. The mean ± SD and median (IQR) for FT4 for all negative TPOAb subjects were 1.19 ± 0.16 and 1.18 (1.08-1.31) ng/dl respectively.

CONCLUSION

Reference ranges for thyroid function tests need to be derived from national databases. This study determined age and sex specific TSH and FT4 reference ranges in a Tehranian population, which could eventually enable clinicians to classify patients more appropriately.

Natural course of thyroid disease profile in a population in nutrition transition: Tehran Thyroid Study

BACKGROUND

There is a lack of data regarding the incidence rate, etiology, risk factors, and natural course of thyroid disorders and their relationship with cardiovascular disease and mortality in populations undergoing nutrition transition. Therefore, we aimed to assess the natural course of thyroid disease in Tehranians, a population in nutrition transition.

METHODS AND DESIGN

Between March 1997 and December 2004, 5769 individuals, aged ≥ 20 years, were selected from district No.13 of Tehran and followed up every three years. Data on risk factors for cardiovascular disease such as diabetes, hyperlipidemia, smoking, obesity, hypertension, low levels of physical activity, and dietary habits were obtained at baseline and again every three years. Cardiovascular and mortality outcomes were assessed in detail.

CONCLUSION

The results of this study will provide a better recognition regarding the incidence and risk factors of thyroid disorders and their relationship with cardiovascular outcomes and mortality in a community in nutrition transition.

Effects of energy-dense nutrient-poor snacks on the incidence of metabolic syndrome: a prospective approach in Tehran Lipid and Glucose Study

OBJECTIVES

Increased consumption of energy-dense, nutrient-poor snacks is one of the major, growing concerns in relation to the alarming trend of overweight, obesity, and metabolic disorders worldwide. The aim of this study was to investigate whether consumption of energy-dense snacks could affect the occurrence of metabolic syndrome after 3 y of follow-up in adults.

METHODS

This longitudinal study was conducted within the framework of the Tehran Lipid and Glucose Study between 2006 and 2008 and 2009 and 2011, on 1466 adults, ages 19 to 70 y. The usual intake of participants was measured using a validated semiquantitative food frequency questionnaire at baseline. Biochemical and anthropometric measurements were assessed at baseline and 3 y later. Multiple logistic regression models were used to estimate the occurrence of metabolic syndrome (MetS) in each quartile of energy-dense snacks.

RESULTS

Participants in the highest quartile of energy-dense snack consumption were significantly younger (33.8 versus 43.1 y; P < 0.01). There were non-significant increased risks for MetS in the highest quartile of biscuits and cakes (odds ratio [OR], 1.13; 95% confidence interval [CI], 0.77-1.66), and candies and chocolates (OR, 1.31; 95% CI, 0.88-1.94). The risk for MetS in participants with highest consumption of salty snacks increased more than 50% (OR, 1.56; 95% CI, 1.01-2.40). Consumption of soft drinks had a borderline effect on the risk for MetS. More than 361 kcal/d from total energy-dense snacks independently increased the occurrence of MetS in the fourth compared the first quartile category (OR, 1.53; 95% CI, 1.03-2.29).

CONCLUSION

The findings of this study demonstrated that higher consumption of energy-dense snacks could be a dietary risk factor for development of MetS.

Establishment of the trimester-specific reference range for free thyroxine index

BACKGROUND

Accurate assessment of thyroid status during pregnancy is vital for maternal and fetal health. Because free thyroxine (FT4) values in pregnancy vary widely between methods, assessment of total T4 (TT4) and FT4 index (FT4I) may be superior to FT4 in pregnant women. However, trimester-specific reference intervals for FT4I have not yet been established. In this longitudinal self-sequential survey, we aimed at determining the trimester-specific reference range for FT4I in healthy Iranian women with singleton pregnancies.

METHODS

A total of 466 healthy pregnant women were evaluated. After exclusion of women with history, ultrasonographic, or laboratory evidence of any thyroid disorder or iodine deficiency and those who were positive for thyroid autoantibodies, 152 women entered the study. Serum thyrotropin (TSH), TT4, and triiodothyronine-resine uptake were measured by an immunoassay method. Reference intervals were defined as 5th and 95th percentiles, using the bootstrap-based procedure.

RESULTS

Mean values in the first, second, and third trimesters were 1.7±1.5, 1.9±1.8, and 1.9±1.8 mIU/L for TSH; 12.9±3, 14.4±3.1, and 13.6±3.3 μg/dL for TT4; and 12.8±3.5, 14.2±3.3, and 13.5±3.8 for FT4I, respectively. Reference intervals in the first, second, and third trimesters were as follows (respectively): TSH-0.2-3.9, 0.5-4.1, and 0.6-4.1 mIU/L; TT4-8.2-18.5, 10.1-20.6, and 9-19.4 μg/dL; and FT4I-8.5-19, 9.7-21, and 8.7-20.4. Serum TSH had no significant correlation with TT4. Serum TSH had a significant but weak correlation with FT4I only in the first trimester (r=-0.24, p=0.006).

CONCLUSION

This study, for the first time, establishes the trimester-specific reference intervals for FT4I in a reference population of normal iodine-sufficient pregnant Iranian women.

Does a text messaging intervention improve knowledge, attitudes and practice regarding iodine deficiency and iodized salt consumption?

OBJECTIVE

To determine the effectiveness of implementation of a prevention programme via mobile phone text messaging in enhancing knowledge, attitudes and practice concerning iodine deficiency and iodized salt consumption.

DESIGN

In a randomized controlled trial, participants were subjected to a brief tele-educational support regarding iodine deficiency and the importance of iodized salt consumption. The intervention group received daily text messages via mobile phone for 6 weeks. Knowledge, attitude and practice scores, urinary iodine concentration and salt iodine content were assessed at baseline and 8 weeks after the intervention.

SETTING

Participants were recruited from health-care centres in Tehran, the capital city of Iran.

SUBJECTS

For the present study 205 females aged ≥18 years were randomly assigned to the intervention (n 95) and control (n 110) groups.

RESULTS

A significant difference was found in median knowledge scores between the intervention and control groups at follow-up (P = 0.004). There was also a significant difference in median attitude scores between the intervention and control groups (P = 0.02). The intervention group did not differ significantly in median practice score, urinary iodine concentration and salt iodine content from the control group.

CONCLUSIONS

Text messaging interventions are effective in improving individuals' knowledge and attitudes regarding preventive health-care topics.

Association between serum TSH concentration and body mass index in euthyroid subjects: the role of smoking

BACKGROUND

Data regarding the influence of minor changes in thyroid function on body mass index (BMI) are scarce and conflicting. This study aims to evaluate the association between normal levels of serum TSH and BMI, taking into consideration the effect of smoking tobacco.

METHODS

In this cross-sectional community-based survey, 1581 randomly selected subjects who had no histories of thyroid disorders were studied within the framework of the Tehran Lipid and Glucose Study. Serum TSH and TPOAb were measured from the fasting serum samples.  Weight and height were measured and BMI was calculated.

RESULTS

TSH concentrations within the reference range were positively associated with BMI (P < 0.002). Each unit increase of 1 µU/ml in TSH was associated with an increase in mean BMI of 0.31 kg/m2 (95% CI: 0.1 - 0.5, P < 0.002), an association which remained significant after adjustments for sex, physical activity, and smoking and in the subgroup with negative thyroid autoimmunity. The association between BMI and TSH remained significant only in nonsmokers (P < 0.004).

CONCLUSION

The results suggest that a significant positive association exists between TSH and BMI in euthyroid nonsmokers.

The incidence of thyroid function abnormalities and natural course of subclinical thyroid disorders, Tehran, I.R. Iran

BACKGROUND

Despite the high prevalence of thyroid dysfunction, the epidemiology and natural course of these disorders have not been identified yet.

AIM

The present survey was conducted to determine the incidence of thyroid dysfunction and natural course of subclinical thyroid disorders in an urban community of Tehran, I.R. Iran.

SUBJECTS AND METHODS

Serum TSH and thyroperoxidase antibody (TPOAb) were measured at baseline and after 6.7 yr from a sample of 1999 randomly selected subjects aged≥20 yr, participants of the Tehran Lipid and Glucose Study (TLGS). Median TSH value and 2.5, 5, 95, and 97.5 TSH percentiles were determined at baseline using data obtained from 808 negative TPOAb subjects with no history of any thyroid disease or surgery, goiter, nodule, taking thyroid hormone preparations or anti-thyroid drugs. In those with abnormal TSH level, total T4 and T3 uptake were measured and free T4 index was calculated.

RESULTS

Normal TSH reference range was 0.4-5.8 μU/ml according to the 2.5 and 97.5 TSH percentiles. The incidence rates of thyroid function abnormalities in 1000 subjects per year were as follows: clinical hypothyroidism: 0.28 in women and 0.21 in men; subclinical hypothyroidism: 11.59 in women and 4.69 in men; clinical hyperthyroidism: 1.4 in women and 0.21 in men; and subclinical hyperthyroidism: 5.72 in women and 3.62 in men. A significant increase was found in the frequency of positive TPOAb in women from 15.9 to 17.7% (p=0.006). Of 8 women with subclinical hypothyroidism at baseline, 5 remained unchanged, 1 became normal, and 1 developed clinical hypothyroidism at followup. Two women with subclinical hyperthyroidism normalized at follow-up. Of 2 men with subclinical hypothyroidism at baseline, 1 remained unchanged, whereas the other progressed to clinical hypothyroidism.

CONCLUSION

After a 6.7 yr follow-up significant increase in the incidence of subclinical thyroid disorders was observed in both men and women, as compared to overt thyroid dysfunction. Increase in the prevalence of TPOAb positivity was observed only in women.

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.

The association of cigarette smoking with serum TSH concentration and thyroperoxidase antibody

BACKGROUND

Although several studies have found an association between tobacco smoking and thyroid disorders such as Graves' disease, Graves' ophtalmopathy, goiter and thyroid multi nodularity, the effect of smoking on thyroid function is controversial.

AIM

The aim of this study was to evaluate the association between smoking and serum TSH concentration and the presence of thyroperoxidase antibody (TPO Ab) in Tehranian adults.

SUBJECTS AND METHODS

In this cross sectional community based survey, 1,581 randomly selected subjects with no history of thyroid disorders were studied within the framework of Tehran Lipid and Glucose Study. Serum TSH and TPOAb were measured in a fasting serum sample. Weight and height were measured and BMI was calculated. Smokers were classified into ever and never smokers based on the declaration of participants.

RESULTS

Mean Ln TSH values in the ever smoker (0.36±0.82) was significantly lower than the never smoker (0.6±0.82) group (p<0.001) even after adjustment for age and BMI. The odds ratio for hypothyroidism (TSH>5.8) was 0.4 in the ever smoker group compared to the never one (odds ratio 0.4, 95% CI=0.2-0.8). The frequency of positive TPOAb in never smokers was significantly higher than ever smokers (%13.5 vs. % 6.7, p<0.001).

CONCLUSION

The results suggest that smoking is associated with decreased serum TSH concentrations, lower risk of hypothyroidism and possibly with a lower frequency of thyroid auto immunity.

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.

Appropriate iodine nutrition in Iran: 20 years of success

Iodine is a trace element in the human body, its only known function is the synthesis of thyroid hormones. Effects of iodine deficiency, termed iodine deficiency disorders (IDD), include endemic goiter, hypothyroidism, cretinism, decreased fertility rate, increased infant mortality and mental retardation. 2.2 billion people worldwide are at risk for IDD. Of these, 30-70% have goiter and 1-10% have cretinism. Two decades ago the I.R. Iran was among the countries most severely affected by iodine deficiency, but during the last two decades has made much progress in the development of universal salt iodization strategies and IDD prevention, and since 1996 meets all WHO/UNICEF/ICCIDD criteria for the sustainable elimination of iodine deficiency.

Thyroid volumes in schoolchildren of the Emirates

Iodine deficiency is a major public health problem, an enlarged goiter being its most apparent manifestation. Recent studies have used US as an accurate and precise method of measuring thyroid size. The aim of this study was to describe thyroid volumes measured by US among school-aged children in the United Arab Emirates. Cross-sectional studies were performed in 4,381 school children, aged 6-17 yr in three locations in the Emirates. Data were collected on age, sex, weight, thyroid size by palpation and US, and urinary iodine. Age/sex and body surface area (BSA) upper limits of thyroid volume were derived. Median urinary iodine in Abu Dhabi, Al Ain and in rural areas of Dubai were 9.9, 12.0 and 9.6 mg/dl respectively. The goiter prevalence by palpation was 28.1%, 26.4% grade 1 and 1.7% grade 2. There was significant difference in median and upper limit of thyroid volumes between boys and girls (p < 0.001). The thyroid volumes of subjects, as assessed by US, progressively increased with age for both sexes (r = 0.53, p < 0.001). In schoolchildren in the Emirates, the best predictors of thyroid volume were BSA, height and weight. The thyroid volumes of the children in this study appear comparable with those reported in a European survey in 1997.

Thyroid volumes in schoolchildren of Tehran: comparison with European schoolchildren

Since the normative values of thyroid volume ultrasonography results from European schoolchildren were endorsed by the World Health Organization (WHO), few studies have addressed the limitation of the recommended references as universal normative values for thyroid volume. Our objective was to describe thyroid volume measured by ultrasonography in Tehranian schoolchildren and compare them with the WHO normative values. Cross-sectional studies were performed in 2016 schoolchildren, aged 6-15 yr, in Tehran 10 yr after distribution of iodized salt. Data were collected on age, sex, weight, height, thyroid size by palpation and ultrasonography, and urinary iodine. Age/sex and body surface area (BSA) upper limits (97th percentile) of thyroid volume were derived. The goiter prevalence was 42% by palpation, 31% grade 1 and 11% grade 2. Median urinary iodine was 21.2 microg/dl. The 97th percentiles were comparable in girls and boys of all ages. Applying the WHO thyroid volume references to the Tehranian children, they did not show any enlarged thyroid based on BSA and on age, even in 11% of children with grade 2 (visible) goiter. In the Tehranian children, the best predictors of thyroid volume were BSA, height and weight. Using linear regression, the 97th percentile of thyroid volume from Tehranian children were lower than the corresponding references from the WHO normative values. The results indicate that a thyroid volume reference based on weight alone would perform as well as the one based on BSA. In addition, until the adoption of a new applicable international reference for thyroid volume, the use of local reference in the screening of children for thyroid enlargement is recommended.