Iodine treatment in children with subclinical hypothyroidism due to chronic iodine deficiency decreases thyrotropin and C-peptide concentrations and improves the lipid profile

Low Urinary Iodine Concentration Is Associated with Increased Risk for Elevated Plasma Glucose in Females: An Analysis of NHANES 2011-12

Iodine intake in the US has declined in recent years. Iodine insufficiency increases the risk for inadequate thyroid hormone production and there is growing evidence that sub-clinical hypothyroidism may be disruptive to metabolic health, including insulin resistance (IR). We investigated the association between urinary iodine concentrations (UIC), a measurement of iodine status, and IR in adults. Data from 1286 US adults (≥20 years) in the NHANES 2011-2012 were analyzed. Two subgroups (low = UIC < 100 µg/L and normal = UIC ≥ 100 µg/L) were compared for markers of IR, including fasting plasma glucose (FPG) and insulin, homeostatic model assessment of insulin resistance (HOMA-IR), and glycated hemoglobin (HbA1C). Chi-square test, both linear and logistic regression models were used. In males, there were no significant associations between UIC and markers of IR; however, females with normal UIC had greater risks for elevated HOMA-IR (AOR = 0.56, 95% CI= 0.32-0.99) and HbA1C (AOR = 0.56, 95% CI = 0.34-0.90), while females with low UIC had a greater risk for FPG ≥ 5.6 mmol/L (AOR = 1.73, 95% CI = 1.09-2.72). Results only partially support our hypothesis that UIC is associated with the odds of IR in adults. The finding of an increased risk for elevated FPG, a marker of prediabetes, in female adults with low iodine status requires further investigation.

Prevention of Iodinated Contrast Media-Induced Hyperthyroidism in Patients with Euthyroid Goiter

INTRODUCTION

Iodinated contrast media (ICM)-induced hyperthyroidism is an underestimated, potentially severe condition; however, its prevention has not been sufficiently investigated. The aim of this study was to evaluate the influence of ICM on thyroid status, the advantages of prophylactic therapy for iodine-induced hyperthyroidism (IIH) in patients with euthyroid goiter and cardiovascular comorbidities, and the association between the incidence of IIH and thyroid volume.

METHODS

Thirty-six euthyroid patients undergoing procedures involving ICM administration were divided into 2 groups: the first group (n = 13) received prophylactic treatment with thiamazole or thiamazole combined with sodium perchlorate during ICM exposure; the second group (n = 23) did not receive prophylaxis. Thyroid-stimulating hormone levels were evaluated before and after ICM, and thyroid hormone levels were assessed after ICM at different points in time. The morphology of the thyroid was evaluated by ultrasonography.

RESULTS

Twenty-one patients (58%) developed hyperthyroidism after ICM. Hyperthyroidism was observed more frequently in the group without prophylactic treatment than in the group with prophylaxis (65 vs. 15%, respectively; p = 0.006). No cases of overt hyperthyroidism were observed in the group receiving thiamazole with sodium perchlorate. IIH persisted for a median time of 52.5 days. Larger thyroid volume was associated with a significantly higher occurrence of ICM-induced hyperthyroidism (p = 0.04).

CONCLUSIONS

Patients with euthyroid goiter receiving ICM are at risk of developing hyperthyroidism. The occurrence of hyperthyroidism after ICM in euthyroid patients with goiter is higher in those with larger thyroid volume. The frequency of ICM-induced hyperthyroidism in euthyroid patients with goiter is lower in those receiving prophylactic therapy with thiamazole in monotherapy or in combination with sodium perchlorate than in those not receiving prophylactic treatment.

Efficacy of a Salt Iodization Program on Iodine Status and Intakes in Schoolchildren of São Miguel Island, Azores, Portugal

INTRODUCTION

Iodine is an essential micronutrient and its deficiency can severely impact children's development. In 2012, the Thyroid Study Group of the Portuguese Society of Endocrinology, Diabetes and Metabolism discovered that the median urinary iodine concentration (mUIC) level in schoolchildren of São Miguel was far too low at 70.9 μg/L. In response, the government implemented a salt iodization program to help normalize levels. This investigation evaluated the efficacy of such an approach.

METHODS

Urinary iodine concentration (UIC) was evaluated in 362 schoolchildren from São Miguel using the fast colorimetric method.

RESULTS

mUIC was 106.7 μg/L, significantly higher than that observed in 2012 (p < 0.001). Over half (55.5%) of the schoolchildren had a UIC >100 μg/L versus 23.0% in 2012 (p < 0.001). 9.4% of schoolchildren had a UIC <50 μg/L, significantly lower than the 30.6% reported in 2012 (p < 0.001).

DISCUSSION/CONCLUSION

Five years after the implementation of the government salt iodization program, the mUIC increased from 70.9 to 106.7 μg/L. This study confirms the efficacy of the adopted measures in schoolchildren population.

Associations between water iodine concentration and the prevalence of dyslipidemia in Chinese adults: A cross-sectional study

Iodine is important in both thyroid function and lipid metabolism. Some studies have explored the effect of thyroid hormones (THs) and urinary iodine concentration (UIC) on serum lipid levels. However, the association between iodine intake and dyslipidemia has not been well established. This study aimed to investigate the relationship between water iodine concentration (WIC) and dyslipidemia, including hypercholesterolemia, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C) and high low-density lipoprotein cholesterol (LDL-C). A cross-sectional survey was conducted involving 409, 390 and 436 adults (≥18 years) from the iodine-deficient (median water iodine, MWI < 10 µg/L), iodine-adequate (MWI between 40 and 100 µg/L) and iodine-excess (MWI > 100 µg/L) areas, respectively. WIC, total cholesterol (TC), triglyceride (TRIG), HDL-C and LDL-C were measured. The prevalence of dyslipidemia were calculated based on the level of WIC using the chi-square method. To further explore whether prevalence was associated with WIC, simple linear regressions and multiple logistic regression models were used. Compared to those with WIC of 40-100 µg/L, a WIC of >100 µg/L was found to be protective associated with against the occurrence of hypertriglyceridemia [adjusted odds ratio (AOR) = 0.649, 95% confidence interval (CI): 0.455-0.924] and low HDL-C (AOR = 0.429, 95% CI: 0.264-0.697). The prevalence of hypertriglyceridemia, low HDL-C and high LDL-C as a function of WIC was found to be an inverted U-shaped association with a zenith at a WIC of 40-100 µg/L. Collectively, our research showed that serum lipid levels are related to WIC. The benefit effect association between WIC and dyslipidemia appears in cases of iodine excess (>100 µg/L).

Iodine Deficiency Increases Fat Contribution to Energy Expenditure in Male Mice

More than a billion people worldwide are at risk of iodine deficiency (ID), with well-known consequences for development of the central nervous system. Furthermore, ID has also been associated with dyslipidemia and obesity in humans. To further understand the metabolic consequences of ID, here we kept 8-week-old C57/Bl6 mice at thermoneutrality (~28°C) while feeding them on a low iodine diet (LID). When compared with mice kept on control diet (LID + 0.71 μg/g iodine), the LID mice exhibited marked reduction in T4 and elevated plasma TSH, without changes in plasma T3 levels. LID mice grew normally, and had normal oxygen consumption, ambulatory activity, and heart expression of T3-responsive gene, confirming systemic euthyroidism. However, LID mice exhibited ~5% lower respiratory quotient (RQ), which reflected a ~2.3-fold higher contribution of fat to energy expenditure. LID mice also presented increased circulating levels of nonesterified fatty acids, ~60% smaller fat depots, and increased hepatic glycogen content, all indicative of accelerated lipolysis. LID mice responded much less to forced mobilization of energy substrates (50% food restriction for 3 days or starvation during 36 hours) because of limited size of the adipose depots. A 4-day treatment with T4 restored plasma T4 and TSH levels in LID mice and normalized RQ. We conclude that ID accelerates lipolysis and fatty acid oxidation, without affecting systemic thyroid hormone signaling. It is conceivable that the elevated plasma TSH levels trigger these changes by directly activating lipolysis in the adipose tissues.

Effects of long-term excessive iodine intake on blood lipids in Chinese adults: a cross-sectional study

OBJECTIVE

The aim of this study was to evaluate the effects of long-term excessive iodine intake on blood lipids in adults.

METHODS

Three counties from Dezhou city and Liaocheng city in the Shandong province of China were selected as survey locations. Three to five villages were selected from each county and then categorized by the iodine concentration detected in the groundwater into Low (<10 µg/L), Medium (10-150 µg/L), High (150-300 µg/L), and Excessive (>300 µg/L) groups. A self-reported questionnaire was completed by each subject to provide demographic characteristics. Body height, weight, and blood pressure were recorded by trained staff. Blood lipids were measured.

RESULTS

A total of 2156 subjects were recruited for the final analysis. The serum triglyceride (TRIG) was significantly higher in the Excessive group than in the other three groups (P < 0.05). Total cholesterol (TCHOL) and low-density lipoprotein-cholesterol (LDL-C) showed downward trends with the increases in the water iodine concentration. A statistical significance of the crude correlation coefficient was detected between the water iodine concentration and the TRIG, TCHOL, or LDL-C (P < 0.05). A significant correlation was also noted between the water iodine concentration and TCHOL or LDL-C after adjustment for covariates. High iodine concentration was a significant protective factor for TCHOL and LDL-C in adults, whereas elevated BMI and advancing age were risk factors for both variables.

CONCLUSION

An association was identified between iodine excess and low TCHOL or LDL-C. In areas with excessive iodine, iodine intake should be considered in studies examining the factors that influence blood lipids.

Appropriate Range of Median Urinary Iodine Concentration in 8- to 10-Year-Old Children Based on Generalized Additive Model

Background: The appropriate range of median urinary iodine concentration (MUI) in children has always been controversial. To prevent the occurrence of a goiter epidemic in Shanghai, we explored the appropriate range of MUI by integrating multiple monitoring results. Methods: This study summarized and analyzed the monitoring data from 1997, 1999, 2011, 2014, and 2017 of children living in Shanghai. In each monitoring year, the probability-proportional-to-size sampling technique was used to select 30 sampling units. In each sampling unit, one primary school was randomly selected. From each selected school, 40 children 8- to 10-year-old were randomly recruited to measure thyroid volume (Tvol) and their household salt iodine intake. Results: In 1997, 1999, 2011, 2014, and 2017, MUI of 8- to 10-year-old children was 228, 214, 182, 171, and 183 μg/L, and median Tvol (MTvol) was 2.9, 1.2, 1.0, 1.8, and 2.8 mL, respectively. There was a linear correlation between goiter rate and MTvol (r = 0.95, p = 0.014; 100 × goiter rate = 1.314 × MTvol -1.287). Generalized additive model (GAM) was used to predict MTvol as follows, MTvol = 0.60689 + 0.00302 MUI +0.999928 s (MUI) -0.05172 mean salt iodized concentrations (MSIs) +0.03481 × 100 × iodized salt coverage rate +0.00000969 per capita disposable income +0.271422 s (per capita disposable income) -0.38772 × monitoring year gap. The results revealed that the average relative error between predicted and actual value was 15.2%. GAM results showed that at 27-277 μg/L MUI, the goiter rate was <5%. Conclusions: Iodine status is appropriate in Shanghai. Under the existing economy and MSI, the optimal range of MUI should be 70-277 μg/L in 8- to 10-year-old children living in Shanghai.

Iodine status of 8 to 10 years old children within 20 years following compulsory salt iodization policy in Shanghai, China

BACKGROUND

In 1996, Shanghai implemented universal salt iodization and has became the last provincial unit in China to carry out this intervention. In this study, we summarized achievements in past 20 years, to provide suggestions and evidence for the next stage of iodine supplementation.

METHODS

This study summarized and analyzed monitoring data of children from 1997, 1999, 2005, 2011, 2014, and 2017 in Shanghai. In each monitoring year, 30 streets or towns were selected using the probability-proportional-to-size sampling technique. One primary school was selected from each street or town by a simple random sampling technique. From each school, 40 children aged 8 to 10 years were randomly selected. The number of children was divided equally by sex and age.

RESULTS

In 1997, 1999, 2005, 2011, 2014, and 2017, median urinary iodine (MUI) was 227.5 μg/L, 214.3 μg/L, 198.1 μg/L, 181.6 μg/L, 171.4 μg/L, and 183.0 μg/L, goiter rate was 3.07, 0.40, 0.08, 0.08, 0.86, and 1.90%, and median thyroid volume (MTvol) was 2.9 mL, 1.2 mL, 2.4 mL, 1.0 mL, 1.8 mL, and 2.8 mL, respectively. There was a linear correlation between goiter rate and median thyroid volume (MTvol) (r = 0.95, P = 0.014). Household salt iodine concentration (SIC) was dropping every monitoring (P < 0.05). There was a significant difference among different household SIC groups in MUI in 1999 and 2017, and in MTvol in 1999 (P < 0.05). No significant differences were detected in the other years.

CONCLUSIONS

In Shanghai, the iodine status of 8 to 10 years old children is adequate. Household SIC have little effect on iodine status of children. Future studies should analyze the dietary sources of iodine, especially from pre-packaged and prepared-away-from-home foods or meals. The regular monitoring of iodine status is important to human health.

Fluoride Exposure Induces Inhibition of Sodium/Iodide Symporter (NIS) Contributing to Impaired Iodine Absorption and Iodine Deficiency: Molecular Mechanisms of Inhibition and Implications for Public Health

The sodium iodide symporter (NIS) is the plasma membrane glycoprotein that mediates active iodide transport in the thyroid and other tissues, such as the salivary, gastric mucosa, rectal mucosa, bronchial mucosa, placenta and mammary glands. In the thyroid, NIS mediates the uptake and accumulation of iodine and its activity is crucial for the development of the central nervous system and disease prevention. Since the discovery of NIS in 1996, research has further shown that NIS functionality and iodine transport is dependent on the activity of the sodium potassium activated adenosine 5'-triphosphatase pump (Na+, K+-ATPase). In this article, I review the molecular mechanisms by which F inhibits NIS expression and functionality which in turn contributes to impaired iodide absorption, diminished iodide-concentrating ability and iodine deficiency disorders. I discuss how NIS expression and activity is inhibited by thyroglobulin (Tg), tumour necrosis factor alpha (TNF-α), transforming growth factor beta 1 (TGF-β1), interleukin 6 (IL-6) and Interleukin 1 beta (IL-1β), interferon-γ (IFN-γ), insulin like growth factor 1 (IGF-1) and phosphoinositide 3-kinase (PI3K) and how fluoride upregulates expression and activity of these biomarkers. I further describe the crucial role of prolactin and megalin in regulation of NIS expression and iodine homeostasis and the effect of fluoride in down regulating prolactin and megalin expression. Among many other issues, I discuss the potential conflict between public health policies such as water fluoridation and its contribution to iodine deficiency, neurodevelopmental and pathological disorders. Further studies are warranted to examine these associations.

Low Urinary Iodine Concentrations Associated with Dyslipidemia in US Adults

Iodine is an essential component of the thyroid hormone which plays crucial roles in healthy thyroid function and lipid metabolism. However, the association between iodine status and dyslipidemia has not been well established at a population level. We aimed to test the hypothesis that the odds of dyslipidemia including elevated total cholesterol, triglycerides, low-density lipoprotein (LDL) cholesterol and apolipoprotein B, and lowered high-density lipoprotein (HDL) cholesterol and HDL/LDL ratio are associated with urinary iodine concentration (UIC) in a population perspective. Data of 2495 US adults (≥20 years) in the National Health and Nutrition Examination Survey 2007–2012 were used in this study. Two subgroups (i.e., UIC below vs. above the 10th percentile) were compared of dyslipidemia as defined based on NCEP ATP III guidelines. The differences between the groups were tested statistically by chi-square test, simple linear regressions, and multiple logistic regressions. Serum lipid concentrations differed significantly between two iodine status groups when sociodemographic and lifestyle covariates were controlled (all, p < 0.05). Those with the lowest decile of UIC were more likely to be at risk for elevated total cholesterol (>200 mg/dL) (adjusted odds ratio (AOR) = 1.51, 95% confidence interval (CI): 1.03–2.23) and elevated LDL cholesterol (>130 mg/dL) (AOR = 1.58, 95% CI: 1.11–2.23) and lowered HDL/LDL ratio (<0.4) (AOR = 1.66, 95% CI: 1.18–2.33), compared to those with UIC above the 10th percentile. In US adults, low UIC was associated with increased odds for dyslipidemia. Findings of the present cross-sectional study with spot urine samples highlight the significant association between UIC and serum lipids at population level, but do not substantiate a causal relationship. Further investigations are warranted to elucidate the causal relationship among iodine intakes, iodine status, and serum lipid profiles.

Randomised controlled trial of the effect of long-term selenium supplementation on plasma cholesterol in an elderly Danish population

Although cross-sectional studies have shown a positive association between Se and cholesterol concentrations, a recent randomised controlled trial in 501 elderly UK individuals of relatively low-Se status found that Se supplementation for 6 months lowered total plasma cholesterol. The Danish PRECISE (PREvention of Cancer by Intervention with Selenium) pilot study (ClinicalTrials.gov ID: NCT01819649) was a 5-year randomised, double-blinded, placebo-controlled trial with four groups (allocation ratio 1:1:1:1). Men and women aged 60-74 years (n 491) were randomised to 100 (n 124), 200 (n 122) or 300 (n 119) μg Se-enriched yeast or matching placebo-yeast tablets (n 126) daily for 5 years. A total of 468 participants continued the study for 6 months and 361 participants, equally distributed across treatment groups, continued for 5 years. Plasma samples were analysed for total and HDL-cholesterol and for total Se concentrations at baseline, 6 months and 5 years. The effect of different doses of Se supplementation on plasma lipid and Se concentrations was estimated by using linear mixed models. Plasma Se concentration increased significantly and dose-dependently in the intervention groups after 6 months and 5 years. Total cholesterol decreased significantly both in the intervention groups and in the placebo group after 6 months and 5 years, with small and nonsignificant differences in changes in plasma concentration of total cholesterol, HDL-cholesterol, non-HDL-cholesterol and total:HDL-cholesterol ratio between intervention and placebo groups. The effect of long-term supplementation with Se on plasma cholesterol concentrations or its sub-fractions did not differ significantly from placebo in this elderly population.

Iodine Supplementation Decreases Hypercholesterolemia in Iodine-Deficient, Overweight Women: A Randomized Controlled Trial

BACKGROUND

In iodine deficiency, thyrotropin (TSH) may increase to stimulate thyroidal iodine uptake. In iodine-sufficient populations, higher TSH predicts higher total cholesterol. Whether higher TSH caused by iodine deficiency affects serum lipids is uncertain.

OBJECTIVE

Our aim was to determine if iodine repletion decreases serum TSH and improves the lipid profile.

METHODS

In this randomized controlled intervention, iodine-deficient, overweight or obese Moroccan women (n = 163) received 200 μg oral iodine or a placebo daily for 6 mo. Main outcomes were serum TSH and plasma total and LDL cholesterol. Secondary outcomes included thyroid hormones and measures of lipid and glucose metabolism and urinary iodine concentration (UIC). Data were compared by using mixed-model analysis.

RESULTS

In the intervention group, median UIC increased from 38 (95% CI: 34, 45) μg/L to 77 (95% CI: 59, 89) μg/L (P < 0.001). After 6 mo of intervention, TSH was 33% lower in the treatment group than in the placebo group (P = 0.024). The triiodothyronine (T3) to thyroxine (T4) ratio and thyroglobulin decreased with treatment [-15% (P = 0.002) and -32% (P < 0.001), respectively], whereas T4 concentrations were higher in the treatment group (P < 0.001). Total cholesterol in subjects with elevated baseline cholesterol (>5 mmol/L) was reduced by 11% after the intervention (P = 0.034). At 6 mo, only 21.5% of treated women remained hypercholesterolemic (total cholesterol >5 mmol/L) vs. 34.8% of controls (baseline: 44.2% in the intervention and 36.8% in the control group; P = 0.015). The reduction in the prevalence of elevated LDL cholesterol (>3 mmol/L) in the intervention group (50.6% to 35.4% compared with 47.4% to 44.9% in the control group) was not significant (P-interaction = 0.23).

CONCLUSIONS

Our findings suggest that moderate to severe iodine deficiency in overweight women elevates serum TSH and produces a more atherogenic lipid profile and that iodine supplementation in this group reduces the prevalence of hypercholesterolemia. Thus, iodine prophylaxis may reduce cardiovascular disease risk in overweight adults. This trial was registered at clinicaltrials.gov as NCT01985204.

2014 European thyroid association guidelines for the management of subclinical hypothyroidism in pregnancy and in children

This guideline has been produced as the official statement of the European Thyroid Association guideline committee. Subclinical hypothyroidism (SCH) in pregnancy is defined as a thyroid-stimulating hormone (TSH) level above the pregnancy-related reference range with a normal serum thyroxine concentration. Isolated hypothyroxinaemia (defined as a thyroxine level below the 2.5th centile of the pregnancy-related reference range with a normal TSH level) is also recognized in pregnancy. In the majority of SCH the cause is autoimmune thyroiditis but may also be due to iodine deficiency. The cause of isolated hypothyroxinaemia is usually not apparent, but iodine deficiency may be a factor. SCH and isolated hypothyroxinaemia are both associated with adverse obstetric outcomes. Levothyroxine therapy may ameliorate some of these with SCH but not in isolated hypothyroxinaemia. SCH and isolated hypothyroxinaemia are both associated with neuro-intellectual impairment of the child, but there is no evidence that maternal levothyroxine therapy improves this outcome. Targeted antenatal screening for thyroid function will miss a substantial percentage of women with thyroid dysfunction. In children SCH (serum TSH concentration >5.5-10 mU/l) normalizes in >70% and persists in the majority of the remaining patients over the subsequent 5 years, but rarely worsens. There is a lack of studies examining the impact of SCH on the neuropsychological development of children under the age of 3 years. In older children, the evidence for an association between SCH and impaired neuropsychological development is inconsistent. Good quality studies examining the effect of treatment of SCH in children are lacking.

Iodine deficiency and subclinical hypothyroidism are common in cystic fibrosis patients

BACKGROUND

Disorders of thyroid function have been inconsistently described in cystic fibrosis (CF) patients and in CF transmembrane regulator protein knockout animals. The literature lacks reports on iodine status of CF individuals. We hypothesize, that iodine deficiency is common in CF and account for abnormal thyroid function in CF patients.

METHODS

We investigated 129 children, adolescents, and adults with CF, who were living in the northern part of Bavaria/Germany. Malnutrition and lung function were analyzed. Urinary iodine excretion, TSH (thyroid-stimulating hormone), and ft4 (free thyroxine) were measured and set in relation to population-based, age-adjusted reference ranges.

RESULTS

Subclinical hypothyroidism (normal fT4, elevated TSH) was found in 11.6% of subjects, and iodine deficiency in 83.7%. No correlations were found with age, BMI, status of malnutrition, or lung function.

CONCLUSION

Dramatic iodine deficiency was found in our cohort of CF patients. This condition can cause subclinical hypothyroidism; therefore, an individual iodine supplementation program is necessary and should be started immediately.

Iodine intake in human nutrition: a systematic literature review

The present literature review is a part of the NNR5 project with the aim of reviewing and updating the scientific basis of the 4th edition of the Nordic Nutrition Recommendations (NNR) issued in 2004. The main objective of the review is to assess the influence of different intakes of iodine at different life stages (infants, children, adolescents, adults, elderly, and during pregnancy and lactation) in order to estimate the requirement for adequate growth, development, and maintenance of health. The literature search resulted in 1,504 abstracts. Out of those, 168 papers were identified as potentially relevant. Full paper selection resulted in 40 papers that were quality assessed (A, B, or C). The grade of evidence was classified as convincing, probable, suggestive, and no conclusion. We found suggestive evidence for improved maternal iodine status and thyroid function by iodine supplementation during pregnancy. Suggestive evidence was found for the relationship between improved thyroid function (used as an indicator of iodine status) during pregnancy and cognitive function in the offspring up to 18 months of age. Moderately to severely iodine-deficient children will probably benefit from iodine supplementation or improved iodine status in order to improve their cognitive function, while only one study showed improved cognitive function following iodine supplementation in children from a mildly iodine-deficient area (no conclusion). No conclusions can be drawn related to other outcomes included in our review. There are no new data supporting changes in dietary reference values for children or adults. The rationale for increasing the dietary reference values for pregnant and lactating women in the NNR5 needs to be discussed in a broader perspective, taking iodine status of pregnant women in the Nordic countries into account.

Micronutrient intake and status in Central and Eastern Europe compared with other European countries, results from the EURRECA network

Objective

To compare micronutrient intakes and status in Central and Eastern Europe (CEE) with those in other European countries and with reference values.

Design

Review of the micronutrient intake/status data from open access and grey literature sources from CEE.

Setting

Micronutrients studied were folate, iodine, Fe, vitamin B12 and Zn (for intake and status) and Ca, Cu, Se, vitamin C and vitamin D (for intake). Intake data were based on validated dietary assessment methods; mean intakes were compared with average nutrient requirements set by the Nordic countries or the US Institute of Medicine. Nutritional status was assessed using the status biomarkers and cut-off levels recommended primarily by the WHO.

Subjects

For all population groups in CEE, the mean intake and mean/median status levels were compared between countries and regions: CEE, Scandinavia, Western Europe and Mediterranean.

Results

Mean micronutrient intakes of adults in the CEE region were in the same range as those from other European regions, with exception of Ca (lower in CEE). CEE children and adolescents had poorer iodine status, and intakes of Ca, folate and vitamin D were below the reference values.

Conclusions

CEE countries are lacking comparable studies on micronutrient intake/status across all age ranges, especially in children. Available evidence showed no differences in micronutrient intake/status in CEE populations in comparison with other European regions, except for Ca intake in adults and iodine and Fe status in children. The identified knowledge gaps urge further research on micronutrient intake/status of CEE populations to make a basis for evidence-based nutrition policy.

Thyroid function in childhood obesity and metabolic comorbidity

Childhood obesity is a worldwide health problem and its prevalence is increasing steadily and dramatically all over the world. Obese subjects have a much greater likelihood than normal-weight children of acquiring dyslipidemia, elevated blood pressure, and impaired glucose metabolism, which significantly increase their risk of cardiovascular and metabolic diseases. Elevated TSH concentrations in association with normal or slightly elevated free T4 and/or free T3 levels have been consistently found in obese subjects, but the mechanisms underlying these thyroid hormonal changes are still unclear. Whether higher TSH in childhood obesity is adaptive, increasing metabolic rate in an attempt to reduce further weight gain, or indicates subclinical hypothyroidism or resistance and thereby contributes to lipid and/or glucose dysmetabolism, remains controversial. This review highlights current evidence on thyroid involvement in obese children and discusses the current controversy regarding the relationship between thyroid hormonal derangements and obesity-related metabolic changes (hypertension, dyslipidemia, hyperglycemia and insulin resistance, nonalcoholic fatty liver disease) in such population. Moreover, the possible mechanisms linking thyroid dysfunction and pediatric obesity are reviewed. Finally, the potential role of lifestyle intervention as well as of therapy with thyroid hormone in the treatment of thyroid abnormalities in childhood obesity is discussed.

Relationships between thyroid function and lipid status or insulin resistance in a pediatric population

BACKGROUND

In adults without thyroid disease, increasing levels of thyroid-stimulating hormone (TSH) within the range of that considered normal have been shown to be associated with increases in total cholesterol, low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, and triglycerides, and with decreases in high-density lipoprotein cholesterol. Serum TSH has also been found to be positively associated with fasting and postload insulin concentrations and negatively associated with insulin sensitivity in euthyroid adults. We hypothesized that such relationships also exist in euthyroid children and adolescents.

METHODS

This was a retrospective record review of pediatric outpatients (ages 2-18 years) having measurements of TSH or free thyroxine (T4) and a concurrent lipid panel, fasting glucose, or fasting insulin. Pearson correlation coefficient was used to estimate the correlation between TSH or free T4 and logarithmic transformed lipid, plasma glucose, or insulin levels. Lipid levels, fasting plasma glucose, insulin, and homeostasis model assessment (HOMA) were also compared between subjects with TSH levels in the high normal range (2.5-5 mIU/L) and those with TSH in the low normal range (0.3-2.4 mIU/L).

RESULTS

TSH levels were positively correlated with triglyceride levels (r = 0.10, p = 0.001). Conversely, free T4 levels were inversely correlated with triglyceride levels (r = -0.10, p = 0.011). TSH levels were also positively correlated with fasting insulin (r = 0.26, p = 0.002) and with HOMA (r = 0.27, p = 0.001). These associations remained significant after adjustment for age, gender, and body mass index z-score. Children who had TSH levels between 2.5 and 5.0 mIU/L had higher triglycerides (p = 0.003), insulin levels (p = 0.040), and HOMA (p = 0.021) than those having TSH values between 0.3 and 2.4 mIU/L.

CONCLUSIONS

In euthyroid children without a history of hypo- or hyperthyroidism, increasing levels of TSH and decreasing levels of free T4 are associated with higher triglyceride levels and elevated markers of insulin resistance. Whether these findings carry implications regarding optimal TSH levels in children at increased risk for cardiovascular disease awaits further study.

A high normal TSH is associated with the metabolic syndrome

OBJECTIVE

Obesity and insulin resistance are key features of the metabolic syndrome. In euthyroidism, the relationships between TSH and insulin resistance or the metabolic syndrome are less clear. We investigated the associations between TSH and the features and prevalence of the metabolic syndrome in euthyroid German subjects.

METHODS

In a cross-sectional study, glucose metabolism was defined by an oral glucose tolerance test (oGTT) (except for those with evident diabetes) in 1333 subjects with TSH values between 0.3 and 4.5 mU/l who did not take any thyroid medication. Lipid parameters were measured, blood pressure and anthromopmetric parameters were taken, and insulin resistance was quantified as HOMA%S.

RESULTS

TSH was weakly correlated with BMI (R = 0.061, P = 0.025). This association remained significant after adjustment for sex, age, and impaired glucose metabolism (P = 0.002). Subjects with a TSH in the upper normal range (2.5-4.5 mU/l, n = 119) had a significantly higher BMI (30.47 +/- 0.57 vs. 28.74 +/- 0.18 kg/m(2), P = 0.001) and higher fasting triglycerides (1.583 +/- 0.082 vs. 1.422 +/- 0.024 mmol/l, P = 0.023), and their likeliness for fulfilling the ATP III criteria of the metabolic syndrome was 1.7-fold increased (95% CI: 1.11- 2.60).

CONCLUSION

In euthyroidism, subjects with a TSH in the upper normal range (2.5-4.5 mU/l) were more obese, had higher triglycerides, and had an increased likeliness for the metabolic syndrome. Therefore, a TSH below 2.5 mU/l is associated with a favourable metabolic profile. Whether lowering TSH to levels below 2.5 mU/l improves metabolism needs to be investigated in intervention trials.

Symposium on 'Geographical and geological influences on nutrition': Iodine deficiency in industrialised countries

Iodine deficiency is not only a problem in developing regions; it also affects many industrialised countries. Globally, two billion individuals have an insufficient iodine intake, and approximately 50% of continental Europe remains mildly iodine deficient. Iodine intakes in other industrialised countries, including the USA and Australia, have fallen in recent years. Iodine deficiency has reappeared in Australia, as a result of declining iodine residues in milk products because of decreased iodophor use by the dairy industry. In the USA, although the general population is iodine sufficient, it is uncertain whether iodine intakes are adequate in pregnancy, which has led to calls for iodine supplementation. The few available data suggest that pregnant women in the Republic of Ireland and the UK are now mildly iodine deficient, possibly as a result of reduced use of iodophors by the dairy industry, as observed in Australia. Representative data on iodine status in children and pregnant women in the UK are urgently needed to inform health policy. In most industrialised countries the best strategy to control iodine deficiency is carefully-monitored salt iodisation. However, because approximately 90% of salt consumption in industrialised countries is from purchased processed foods, the iodisation of household salt only will not supply adequate iodine. Thus, in order to successfully control iodine deficiency in industrialised countries it is critical that the food industry use iodised salt. The current push to reduce salt consumption to prevent chronic diseases and the policy of salt iodisation to eliminate iodine deficiency do not conflict; iodisation methods can fortify salt to provide recommended iodine intakes even if per capita salt intakes are reduced to <5 g/d.