Age- and gender-dependent urinary iodine concentrations in an area-covering population sample from the Bernese region in Switzerland

Factors influencing the iodine status of children aged 12 to 59 months from Jaffna District, Sri Lanka in the post-iodization era; a descriptive, cross-sectional study

BACKGROUND

Iodine status, including Iodine Deficiency (ID) of the children aged 12-59 months of Jaffna District, Sri Lanka, have never been studied. This study thus aimed to assess ID among children aged 12-59 months by monitoring the Urinary Iodine Concentrations (UIC), the prevalence of goitre, and the factors causing ID.

METHOD

A cross-sectional study was conducted among 846 children aged 12-59 months in Jaffna District, Sri Lanka. Sociodemographic characteristics and other factors were collected using an interviewer-administered questionnaire. Dietary pattern of children was obtained using semi-quantitative food frequency questionnaire. We performed urinary iodine estimation and physical examinations to detect the goitre, according to the World Health Organization criteria. A multivariate logistic linear regression model was used to identify the factors that causing ID.

RESULT

The median UIC was 146.4 μg/L (interquartile range = 112.6-185.3 μg/L). Based on the UIC (<100 μg/L), 17.8% had ID, of which 15.7% and 2.1% had mild and moderate ID. The mean consumption of iodine from food was 128.7 (±20.2) μg/day. Gender variation had no influence on ID (p>0.05). Median UIC was significantly associated with living area, wealth status, type of drinking water, and method of iodized salt usage. A higher percentage of ID was significantly associated with younger age [AOR 2.32 (95% CI: 1.31-4.10)], urban area [AOR 1.94 (95% CI 1.27-2.96)], inland regions [AOR 3.20 (95% CI 1.85-5.55)], improper method of iodized salt usage [AOR 3.63 (95% CI: 1.38-9.56)], and low consumption of iodine-containing foods. The neck palpation revealed that only three children had goitre (0.4%).

CONCLUSION

This study revealed that high ID among the children in Jaffna children was due to improper usage of iodized salt, even though the iodized salt is freely available in the region, living area, and age, while the prevalence of goitre was not significantly identified as a public health problem.

Iodine status in women attending Mnazi Mmoja Hospital in Zanzibar: a matched case-control study

Background

Iodine deficiency can have adverse health effects in all age groups affecting growth, development and cognitive functions as well as the incidence of goitre. Worldwide, the most important dietary source of iodine is iodised salt. In Tanzania, iodine intake has varied due to multiple salt suppliers producing iodised salt with varying quality. Zanzibar has faced challenges with the packing, storing and monitoring of salt iodisation, and universal salt iodisation has not been achieved. Furthermore, the number of available studies on the iodine status in Zanzibar are sparse.

Objective

The main objective of this study is to describe the iodine status of euthyroid female adult patients with and without goitre in Zanzibar.

Design and methods

A single-centre matched case-control study was conducted among 48 female patients at the ear, nose and throat clinic of Mnazi Mmoja Hospital, Zanzibar. Blood samples were drawn for serum-analysis of the thyroid hormone profile to confirm that all patients were euthyroid prior to inclusion. Urinary iodine concentrations and the iodine concentration in household salt samples were analysed. A semiquantitative food frequency questionnaire (FFQ) was used to describe trends in the dietary intake of iodine-rich and goitrogenic foods. Clinical examinations were conducted, and the patients were categorised into goitre (cases) and non-goitre (controls) groups.

Results

A moderate iodine deficiency (median urinary iodine concentration between 20 and 49 µg/L) was found in patients both with and without goitre. In total, only 35 % of the salt samples were adequately iodised. The salt samples from the cases had a lower average concentration of iodine compared with the controls. The FFQ revealed that the daily consumption of marine fish and the weekly consumption of raw cassava were more frequent in the cases than the controls.

Conclusion

These findings suggest that iodine deficiency may be a problem in both patients with and without goitre in Zanzibar. The salt iodisation programme may require monitoring and implementation of satisfactory quality control practices as universal salt iodisation is yet to be achieved in Zanzibar.

Spot urine iodine levels below the WHO recommendation are not related to impaired thyroid function in healthy children and adolescents

PURPOSE

Iodine deficiency in childhood and adolescence may lead to later thyroid dysfunction, stunted growth and cognitive impairment. The World Health Organization (WHO) has issued recommended age-dependent urine iodine concentration targets, but a critical threshold beyond which clinical sequelae are to be expected remains undefined. Our study aimed to investigate spot urine iodine concentration in a typical Central European cohort of children and adolescents, and consider the implications of these values in regard to laboratory parameters for evaluating thyroid function.

METHODS

Using the Sandell-Kolthoff method, spot urine iodine concentration was measured cross-sectionally from 1802 healthy children and adolescent in the age range of 0.25-18 years within the LIFE-Child epidemiological study based in and around the city of Leipzig (Germany). Additionally, serum thyroid biomarkers of these subjects were measured and correlated to urine iodine levels.

RESULTS

In our cohort, 61.39% of boys and 65.91% of girls had an iodine level of < 100 µg/L (57%, 67%, 65% of the age groups 0-5, 6-12 and 13-18 years), the median iodine excretion was 86 µg/L in boys and 80 µg/L in girls. The iodine levels revealed no significant correlation with the thyroid biomarkers TSH, FT4 and FT3. Moreover, iodine values revealed no correlation with levels of antibodies against thyroid peroxidase or thyroglobulin.

CONCLUSION

In our cohort of children and adolescents, the relatively high number of iodine levels below the WHO recommendation appears not to be related to clinical or subclinical thyroid diseases in the respective participants.

Iodine levels in different regions of the human brain

BACKGROUND

Iodine is a key component of the thyroid hormones thyroxine (T4) and triiodothyronine (T3), which are crucial for proper growth and development of the human body. In particular, a great body of literature has been published on the link between thyroid hormones and brain development and functioning. However, there is a lack of knowledge on the iodine levels in the human brain. The aim of this work was to determine the brain iodine levels and to contribute to the establishment of "reference" levels for iodine in the different anatomical and functional regions of normal (i.e., subjects without neurological or psychiatric diseases) human brain.

METHODS

The iodine levels were determined in 14 brain regions of 52 dead subjects without evidence of neurological or psychiatric disease (n = 728 samples). Iodine was extracted from brain samples using a standard procedure and determined by inductively coupled plasma - mass spectrometry (ICP-MS).

RESULTS

Four subjects presented abnormally high brain iodine levels (26.0 ± 14.2 μg/g) and were excluded from the overall data analysis. The average brain iodine levels for the remaining 48 subjects was 0.14 ± 0.13 μg/g dry weight. Iodine showed very heterogeneous distribution across the different brain regions, with the frontal cortex, caudate nucleus and putamen showing the highest levels. Interestingly, these brain regions are closely related to cognitive function. Iodine levels also showed a tendency to increase with age. The high levels observed in four subjects seemed to be related to previous exposure to iodine-based contrast agents widely used in radiology and computed tomography exams.

CONCLUSIONS

This paper provides important data on iodine levels at different brain regions in "normal" people, which can be used to interpret eventual imbalances in subjects with mental disorders and neurodegenerative diseases.

Variation of iodine status during pregnancy and its associations with thyroid function in women from Rio de Janeiro, Brazil

OBJECTIVE

To assess iodine status and its effects on maternal thyroid function throughout pregnancy.

DESIGN

In the present prospective cohort study, three urinary samples were requested for urinary iodine concentration (UIC) determinations in both the first and third gestational trimesters. Serum thyrotropin (TSH) and free thyroxine (FT4) were analysed in both trimesters and thyroid antibodies were assessed once.

SETTING

Rio de Janeiro, Brazil.ParticipantsFirst-trimester pregnant women (n 243), of whom 100 were re-evaluated during the third trimester.

RESULTS

Iodine sufficiency was found in the studied population (median UIC=216·7 µg/l). The first- and third-trimester median UIC was 221·0 and 208·0 µg/l, respectively. TSH levels (mean (sd)) were higher in the third trimester (1·08 (0·67) v. 1·67 (0·86) mIU/l; P&lt;0·001), while FT4 levels decreased significantly (1·18 (0·16) v. 0·88 (0·12) ng/dl; P&lt;0·001), regardless the presence of iodine deficiency (UIC&lt;150 µg/l) or circulating thyroid antibodies. UIC correlated (β; 95% CI) independently and negatively with age (-0·43; -0·71, -0·17) and positively with multiparity (0·15; 0·02, 0·28) and BMI (0·25; 0·00, 0·50). Furthermore, median UIC per pregnant woman tended to correlate positively with TSH (0·07; -0·01, 0·14). Women with median UIC≥250 µg/l and at least one sample ≥500 µg/l throughout pregnancy had a higher risk of subclinical hypothyroidism (OR=6·6; 95% CI 1·2, 37·4).

CONCLUSIONS

In this cohort with adequate iodine status during pregnancy, excessive UIC was associated with an increased risk of subclinical hypothyroidism.

Iodine Status of Taiwanese Population in 2013: 10 Years After Changing From Mandatory to Voluntary Salt Iodization

BACKGROUND

In 2003, Taiwan's iodine policy changed from mandatory to voluntary. The Nutrition and Health Survey in Taiwan (NAHSIT) 2001-2002 for schoolchildren showed adequate iodine nutrition, while NAHSIT 2005-2008 for adults showed the iodine status was at borderline adequacy.

OBJECTIVE

To investigate the iodine status of the Taiwanese population from schoolchildren to adulthood 10 years after the change of the salt iodization policy.

METHOD

Urinary iodine was measured in samples from subjects in NAHSIT 2013.

RESULTS

The median urinary iodine concentration (UIC) of the Taiwanese population aged 6 years and above in 2013 was 96 μg/L, indicating mild iodine deficiency. The median UIC of 6- to 12-year-old schoolchildren was 124 μg/L (interquartile range [IQR]: 92-213 μg/L), and 115 μg/L (IQR: 80-166 μg/L), 125 μg/L (IQR: 74-161 μg/L), 73 μg/L (IQR: 52-131 μg/L), and 78 μg/L (IQR: 52-132 μg/L) in populations aged 13 to 18 years, 19 to 44 years, 45 to 64 years, and ≥65 years, respectively. Declining iodine nutrition in age groups ≥45 years old was noted that the median UIC of populations aged 45 to 64 years and ≥65 years was 99 and 88 μg/L, respectively, in NAHSIT 2005-2008. The median UIC of schoolchildren was not lower than that during the mandatory salt fortification period, but the distribution of urinary iodine levels signified a dietary pattern change.

CONCLUSION

Wide-ranging variation in iodine nutrition levels was observed in different age groups. Universal salt iodization, as suggested by the World Health Organization, should be the best strategy to achieve adequate iodine nutrition.

Iodine Intakes of Victorian Schoolchildren Measured Using 24-h Urinary Iodine Excretion

Mandatory fortification of bread with iodized salt was introduced in Australia in 2009, and studies using spot urine collections conducted post fortification indicate that Australian schoolchildren are now replete. However an accurate estimate of daily iodine intake utilizing 24-h urinary iodine excretion (UIE μg/day) has not been reported and compared to the estimated average requirement (EAR). This study aimed to assess daily total iodine intake and status of a sample of primary schoolchildren using 24-h urine samples. Victorian primary school children provided 24-h urine samples between 2011 and 2013, from which urinary iodine concentration (UIC, μg/L) and total iodine excretion (UIE, μg/day) as an estimate of intake was determined. Valid 24-h urine samples were provided by 650 children, mean (SD) age 9.3 (1.8) years (n = 359 boys). The mean UIE of 4–8 and 9–13 year olds was 94 (48) and 111 (57) μg/24-h, respectively, with 29% and 26% having a UIE below the age-specific EAR. The median (IQR) UIC was 124 (83,172) μg/L, with 36% of participants having a UIC < 100 μg/L. This convenience sample of Victorian schoolchildren were found to be iodine replete, based on UIC and estimated iodine intakes derived from 24-h urine collections, confirming the findings of the Australian Health Survey.

Urinary iodine and thyroid function in a population of healthy pregnant women in the North of Spain

BACKGROUND

Iodine is an essential trace element for the synthesis of thyroid hormones, which are keys in maternal metabolism during pregnancy as well as in neurological development during fetal and postnatal life. This was a prospective study on iodine status and thyroid function in women during pregnancy in the Basque country to assess whether there was any relationship among maternal urinary iodine, maternal thyroid function and thyrotropin (TSH) in newborns, and to explore any difference in women experiencing miscarriages.

METHODS

We analyzed TSH, free T(4) (FT(4)), free T(3) (FT(3)), thyroid peroxidase antibody (TPO-Ab) titers in serum and urinary iodine concentrations (UIC) in 2104 women in the first trimester of pregnancy and in 1322 of them in their second trimester. We obtained neonatal TSH levels in 1868 cases.

RESULTS

In the first (T1) and second trimesters (T2), the median UICs were 88.5 μg/L and 140 μg/L, respectively. No relationship was found between UIC and FT4, or maternal and neonatal TSH. In T1 and T2, 9.7% and 7.5% of women were TPO-Ab positive, respectively. The total miscarriage rate was 10%. The percentage of miscarriages in healthy women was 8.9%, lower than in women with overt hypothyroidism (21.2%; p < 0.001) and than in women with subclinical hypothyroidism (15.6%; p < 0.025). The miscarriage rate was not higher in TPO-Ab-positive women.

CONCLUSIONS

In this study most women had iodine deficiency during pregnancy. Neonatal TSH is not correlated with maternal UIC during pregnancy. Pregnant women with hypothyroidism have a higher rate of miscarriages.

Iodine nutrition status and knowledge, attitude, and behavior in Tehranian women following 2 decades without public education

OBJECTIVE

To evaluate the association of iodine nutrition status and knowledge, attitude, and behavior in Tehranian women after 2 decades without updating public education.

DESIGN

Cross-sectional study.

SETTING

Eight health care centers from 4 district areas of Tehran.

PARTICIPANTS

A total of 383 women aged ≥ 19 years, randomly selected.

MAIN OUTCOME MEASURES

Iodine concentration of 24-hour urine samples, iodine content of household salts, and knowledge, attitude, and practice scores regarding iodine nutrition and iodized salt.

ANALYSIS

Multiple logistic regression was used to identify the association of knowledge, attitude, and practice scores with urinary iodine concentration (UIC) < 100 μg/L.

RESULTS

The percentages of Tehranian women with high knowledge, attitude, and practice scores were 26%, 26%, and 14%, respectively. Practice score was significantly different between females with UIC < 100 and > 100 μg/L (P = .001). Risk of UIC < 100 μg/L in women of childbearing age (19-45 years) after adjustment of education level, region of residence, and iodine content of salt was significantly associated with intermediate practice score (odds ratio = 2.6; 95% confidence interval, 1.3-13.2).

CONCLUSIONS AND IMPLICATIONS

Marginally suboptimal iodine status in women of childbearing age can be attributed to inappropriate practices, but not to knowledge and attitude.

EURRECA-Estimating iodine requirements for deriving dietary reference values

Iodine is an essential component of thyroid hormones, and current recommendations for intake are based on urinary iodine excretion, assessment of thyroid size, thyroidal iodine accumulation and turnover, radioactive iodine uptake, balance studies, and epidemiological studies. Dietary iodine is rapidly and almost completely absorbed. The prevalence of inadequate iodine intake is high: 29% of the world's population lives in iodine-deficient areas and 44% of Europe remains mildly iodine deficient. To assess current data and update evidence for setting dietary recommendations for iodine, the EURRECA Network of Excellence has undertaken systematic review and evaluation of (i) the usefulness of iodine status biomarkers (ii) the relationship between iodine status biomarkers and dietary iodine intake, and (iii) the relationship between iodine intake and health outcomes (endemic goiter, hypothyroidism, and cognitive function). This review summarizes the main research outputs: the key findings of the literature review, results of the meta-analyses, and discussion of the main conclusions. Currently, data for relevant intake-status-health relationships for iodine are limited, particularly for population groups such as children under two years, pregnant women, and the elderly. The EURRECA Network developed best practice guidelines for the identification of pertinent iodine studies based on a systematic review approach. This approach aimed to identify comparable data, suitable for meta-analysis, for different countries and across all age ranges. When new data are available, the EURRECA Network best practice guidelines will provide a better understanding of iodine requirements for different health outcomes which could be used to set evidence-based dietary iodine recommendations for optimal health.

Ten repeat collections for urinary iodine from spot samples or 24-hour samples are needed to reliably estimate individual iodine status in women

Although the median urinary iodine concentration (UIC) is a good indicator of iodine status in populations, there is no established biomarker for individual iodine status. If the UIC were to be used to assess individuals, it is unclear how many repeat urine collections would be needed and if the collections should be spot samples or 24-h samples. In a prospective, longitudinal, 15-mo study, healthy Swiss women (n = 22) aged 52-77 y collected repeated 24-h urine samples (total n = 341) and corresponding fasting, second-void, morning spot urine samples (n = 177). From the UIC in spot samples, 24-h urinary iodine excretion (UIE) was extrapolated based on the age- and sex-adjusted iodine:creatinine ratio. Measured UIE in 24-h samples, estimated 24-h UIE, and UIC in spot samples were (geometric mean ± SD) 103 ± 28 μg/24 h, 86 ± 33 μg/24 h, and 68 ± 28 μg/L, respectively, with no seasonal differences. Intra-individual variation (mean CV) was comparable for measured UIE (32%) and estimated UIE (33%). The CV tended to be higher for the spot UIC (38%) than for the estimated 24-h UIE (33%) (P = 0.12). In this population, 10 spot urine samples or 24-h urine samples were needed to assess individual iodine status with 20% precision. Spot samples would likely be preferable because of their ease of collection. However, the large number of repeated urine samples needed to estimate individual iodine status is a major limitation and emphasizes the need for further investigation of more practical biomarkers of individual iodine status.

Iodine status of the U.S. population, National Health and Nutrition Examination Survey 2003-2004

BACKGROUND

Since 1971, the general U.S. population has been monitored for dietary iodine sufficiency by urinary iodine (UI) measurements through the National Health and Nutrition Examination Survey (NHANES). This report presents the UI levels for the population participating in NHANES 2003-2004. It is the third assessment of the U.S. population since NHANES III (1988-1994), when the median UI level was observed to decrease from NHANES I (1971-1974).

METHODS

In 2003-2004, a stratified, multistage, probability sample of approximately 5000 participants per year were selected to participate in NHANES Household interviews, and specimen collection were performed. UI level was measured by inductively coupled plasma mass spectrometry on a random subsample of 2526 participants aged 6 years and older.

RESULTS

The median UI level for the general U.S. population in 2003-2004 was 160 microg/L (95% confidence interval [CI] 146-172), and 11.3 +/- 1.8% of the population had a UI level below 50 microg/L. Children had a higher UI level than adolescents and adults. Among all (pregnant and nonpregnant) women of reproductive age, the median UI level was 139 microg/L (95% CI 117-156), 15.1 +/- 3.2% women had a UI level <50 microg/L, and Non-Hispanic blacks in this group had a lower UI level than other racial/ethnic groups.

CONCLUSIONS

These findings affirm the stabilization of the UI level and the adequate iodine nutrition in the general U.S. population since 2000. Future surveys designed to achieve UI levels representative of pregnant women can improve the estimate of iodine sufficiency in this population subgroup. Continued monitoring of the population for iodine sufficiency is warranted because of groups at risk for iodine deficiency disorders.

Iodine intake before and after mandatory iodization in Denmark: results from the Danish Investigation of Iodine Intake and Thyroid Diseases (DanThyr) study

Iodine deficiency is still common in some European countries. In Denmark an iodine fortification programme was introduced in 1998 and a monitoring programme was established prior to iodization. This study reports the change in urinary iodine excretion caused by fortification and investigates determinants of iodine intake after fortification. Iodine excretion in casual urine samples was assessed in 4649 subjects in 1997–8 and in 3570 comparable subjects in 2004–5 in women 18–22, 25–30, 40–45 and 60–65 years of age and in men 60–65 years of age living in Aalborg (western part of Denmark) or Copenhagen (eastern part of Denmark). These areas had moderate and mild iodine deficiency, respectively, before iodine fortification. All subjects filled in a FFQ and a questionnaire regarding lifestyle factors. Iodine excretion, expressed as the estimated 24 h urinary iodine excretion and as urinary iodine concentration, increased significantly in all age and sex groups. However, the iodine intake was still below the recommended in the youngest age groups in both cities and in women 40–45 years of age living in Aalborg. Intake of milk and salt had strong significant direct associations with iodine excretion (P < 0·001). It is concluded that although the median iodine intake in the whole study population is at the recommended level, some groups still have an intake below the recommended. It is important to have a moderate milk intake to obtain a sufficient iodine intake in Denmark.

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.

Pilot study of urinary iodine concentration and of biochemical thyroid parameters before and after cautious public health intervention on salt iodide content: The Swiss longitudinal 1996–2000 iodine study

OBJECTIVE AND DESIGN

Iodide concentration (IC) in salt was cautiously increased in Switzerland (15 --> 20 ppm iodide). We evaluated the dynamics of the effect of this intervention on urinary iodine concentration (UIC, microg/l) and on thyroid parameters.

SETTING

University Hospital in Bern, Switzerland.

SUBJECTS

A cohort of 36 subjects (12 children, 11 women, 13 men) out of 44 were recruited.

INTERVENTIONS

During the study periods PRE (May 1996-May 1998) and POST (October 1998-December 2000, subdivided into equal subperiods POST1 and POST2), that is, before and after the increase of IC in salt, subjects collected 6248 urine spots for analysis of UIC. Thyroid volumes (n=2/subject) and serum thyroid parameters (n=8/subject) were sequentially evaluated.

METHODS

Average PRE-POST data were compared (multiple regression analysis).

RESULTS

UIC increased overall by 5.1% (P=0.0003). Increase of UIC was highest in children (11.3%, P<0.0001), significant in women (8%, P=0.0016), but not significant in men (P=0.143). Comparison between periods POST1 and POST2 showed that UIC changed more gradually in women than in children. Thyroid volumes were normal, no nonphysiological change occurred. TSH indicated euthyroidism; it decreased in children (1.98 ==> 1.74 mU/l, P=0.04) and increased in men (1.65 ==> 1.91mU/l, P=0.025). FT3 decreased in children (P<0.004) and FT4 decreased in men (P=0.017), both within normal ranges. TSH, FT3 and FT4 were unchanged in women. FT3/FT4 ratios were stable. Anti-TPO-Ab titers were stable (P=0.9). Anti-Tg-Ab titers decreased (P=0.009).

CONCLUSION

The significant UIC effects were of uncertain metabolic relevance. No pathological side effects occurred. Differential delays and penetrances of UIC increase in children and adults were hitherto unknown. The unspectacular stepwise policy seems to be safe. Our pilot results in a population with moderate iodine deficiency in women should be confirmed in population-based cluster studies.

SPONSORSHIP

This work was supported by grants from the University Hospital in Bern, the Swiss Federal Office of Public Health (SFOPH), the 'Swiss National Foundation for Scientific Research' (32-49424.96), the 'Fondation Genevoise de Bienfaisance Valerie Rossi di Montelera', the 'Schweizerische Lebensversicherungs- und Rentenanstalt' and the 'Schüpbach Foundation of the University of Bern'.

Screening a coastal population in Southern Italy: iodine deficiency and prevalence of goitre, nutritional aspects and cardiovascular risk factors

BACKGROUND AND AIM

To evaluate the prevalence of goitre by means of urinary iodine excretion, palpatory and ultrasonographic thyroid examinations in a heterogeneous population living by the sea.

METHODS AND RESULTS

We used a special self-administered questionnaire to evaluate thyroid size, iodine intake, eating habits and cardiovascular risk factors in 600 subjects with a mean age of 45 +/- 17 years: 253 men (42.3%) and 347 women (57.7%). Urinary iodine excretion was low (72.1 +/- 15.7 microg/L; median 71.2) and associated with ultrasonographic evidence of an enlarged thyroid (16%) or structural thyroid abnormalities (30%), thus allowing us to define the Salerno Gulf as a mild-moderate area of endemic goitre. All of the subjects ate a Mediterranean diet, with a mean of two portions of fish/week. The cardiovascular risk factors considered were obesity, cigarette smoking, hypertension, hypercholesterolemia, hypertriglyceridemia and diabetes, the prevalences of which were in line with those reported in other studies of similar age-matched populations.

CONCLUSIONS

The moderate intake of fish and the consumption of a Mediterranean diet did not prevent goitre. Iodine deficiency and subsequent goitre endemia are also present at sea level, probably because of a diet based on local products grown on soil with a low iodine content or possible seawater, soil and air environmental pollution that may interfere with the availability of iodine. The assessment of iodine deficiency should therefore involve the entire population and not only subjects living far from the sea.

Urinary iodine concentration during pregnancy in an area of unstable dietary iodine intake in Switzerland

We prospectively investigated urinary iodine concentration (UIC) in pregnant women and in female, non-pregnant controls in the canton of Berne, Switzerland, in 1992. Mean UIC of pregnant women [205 +/- 151 microg iodine/g creatinine (microg l/g Cr); no. = 153] steadily decreased from the first (236 +/- 180 microg l/g Cr; no. = 31) to the third trimester (183 +/- 111 microg l/g Cr, p < 0.0001; no. = 66) and differed significantly from that of the control group (91 +/- 37 microg l/g Cr, p < 0.0001; no. = 119). UIC increased 2.6-fold from levels indicating mild iodine deficiency in controls to the first trimester, demonstrating that high UIC during early gestation does not necessarily reflect a sufficient iodine supply to the overall population. Pregnancy is accompanied by important alterations in the regulation of thyroid function and iodine metabolism. Increased renal iodine clearance during pregnancy may explain increased UIC during early gestation, whereas increased thyroidal iodine clearance as well as the iodine shift from the maternal circulation to the growing fetal-placental unit, which both tend to lower the circulating serum levels of inorganic iodide, probably are the causes of the continuous decrease of UIC over the course of pregnancy. Mean UIC in our control group, as well as in one parallel and several consecutive investigations in the same region in the 1990s, was found to be below the actually recommended threshold, indicating a new tendency towards mild to moderate iodine deficiency. As salt is the main source of dietary iodine in Switzerland, its iodine concentration was therefore increased nationwide in 1998 for the fourth time, following increases in 1922, 1965 and 1980.

Swiss pilot study of individual seasonal fluctuations of urinary iodine concentration over two years: is age-dependency linked to the major source of dietary iodine?

OBJECTIVE

Because of known significant seasonal fluctuations of iodine concentration in cow's milk (ICM) in Switzerland (winter/summer (w/s) ICM ratio averages 5.6), we looked for seasonal variations and familial aspects in urinary iodine and sodium concentrations (UIC, UNaC).

DESIGN

: Prospective sequential cohort investigation.

SETTING

University hospital.

SUBJECTS

Thirteen children (six girls, seven boys) aged 3-10 y and their parents (n=9) aged 30-47 y.

INTERVENTIONS

The volunteers collected 1729 spot urine samples (5.1996-5.1998). UIC data from winter (UIC(w): December-February) and summer seasons (UIC(s): July-September) were compared with UNaC and average milk consumption. Iodine intakes from milk and salt were modelized.

RESULTS

Highest seasonal fluctuations of UIC were found in six pre-school children (w/s UIC group average=1.56, significant), followed by seven school children (w/s UIC group average=1.24, N.S.); none existed in adults. UIC/UNaC showed corresponding seasonal fluctuations in children, but not in adults. Winter milk was an important iodine source for children, as proven indirectly by similar seasonal fluctuations of ICM, UIC, UIC/UNaC and an important part within UIC due to milk.

CONCLUSIONS

Contribution to UIC from milk intake during winter was high in children (40-50%) and lower in adults (about 20%). Compared with children, dietary habits of adults are more complex and their iodine supply depends mainly on iodized salt and not on milk, so the effect of seasonal ICM variations on UIC is less marked. Because of significant seasonal UIC fluctuations in consumers of fresh milk products in Switzerland, results of future UIC studies conducted during summer and winter seasons should be compared cautiously, especially in young children. Furthermore, consumption of milk is to be promoted, since, besides calcium and vitamins, it is an essential source of iodine. UNaC determination should be included in epidemiologic studies if the dietary source of iodine is questioned.

[Iodine nutritional status and risk factors for iodine deficiency in infants and children of the french North department]

INTRODUCTION

Iodine deficiency is responsible for a higher mortality and morbidity in neonates and infants. It has not yet disappeared in European countries, especially in Southern and Eastern Europe.

OBJECTIVES

The present study aimed at evaluating the status of iodine nutrition of infants living in the North department (France) and at studying risk factors for iodine deficiency.

METHODS

The study was conducted in primary health care centres in 160 healthy infants aged ten days to six years (mean +/- SD: 17.7 +/- 2.5 months). Data included: familial thyroid disease history, type of feeding at inclusion, timing of introduction of complementary foods, nutritional status (weight, height, head and arm circumference), as well as maternal education level and family socio-economical status. Iodine status was assessed by urinary iodine excretion.

RESULTS

Urinary iodine concentration ranged from 4 to 1042 microg/l (median +/- SD: 195,5 +/- 21,6 microg/l). Thirty-eight (24%) of 160 children were iodine deficient (urinary iodine < 100 microg/l): mild iodine deficiency (50-99 microg/l: 17%), moderate iodine deficiency (20-49 microg/l: 5%), severe iodine deficiency (<20 microg/l: 2%). No relationship was found between iodine status and age, sex, geographic origin of the children, as well as social and occupational group of the parents. Breast-feeding did not prevent from iodine deficiency. Iodine status did not differ between the cow's milk fed group and the group that was not fed cow's milk. Formula feeding was associated with iodine deficiency (p = 0,02).

CONCLUSIONS

Prevalence of severe iodine deficiency was very low in this population. However, iodine status was not optimal.

Visible signs of illness from the 14th to the 20th century: systematic review of portraits

OBJECTIVES

To see whether a collection of portraits depicting inhabitants of a defined geographical region and covering several centuries is a useful source for studying the sociocultural significance and epidemiology of particular visible diseases, such as goitre, which is known to have been common in this region.

DESIGN

Systematic review of portraits and description of visible signs of illness.

SETTING

The Burgerbibliothek (archives of the burghers' community) in Berne, Switzerland.

DATA SOURCES

3615 portraits; 2989 of individuals whose identity is known and 626 of individuals whose identity is unknown.

MAIN OUTCOME MEASURES

Visible signs of illness evaluated by means of a standardised visual assessment.

RESULTS

Visible signs of illness in portraits were common and appeared in up to 82% (451/553) of paintings from the 17th and 18th centuries. The most common findings were signs of goitre in women and overweight in men. In only the portraits where the neck region could be evaluated, 41% of women with known identities (139/343) had goitre compared with 24% of men with known identities (21/86). The prevalence of goitre was even higher in sitters whose identities were unknown: 63% in men (5/8) and 68% in women (82/121). Overweight in people with known identities was more common in men than in women (30%, 346/1145 v 44%, 811/1844). Overweight was most common in sitters aged >40 than in those aged 40 or younger. Other conditions, such as missing teeth, amputated limbs, or osteoarthritic deformations were surprisingly rare in the portraits under evaluation.

CONCLUSIONS

Goitre and other diseases are under-represented in the people depicted in these portraits. Artistic idealisation is a likely explanation for this observation: what was reproduced depended on what was considered pathological or shameful at the time, and therefore depended on age and sex. Stigmatising details may have been omitted. Further, artistic skills and contemporary fashion may have influenced the way in which people were reproduced. People depicted are possibly not representative of the general Bernese population as they constituted a socioeconomically advantaged group.

Controversies in urinary iodine determinations

Iodine deficiency (ID) is associated with increased prevalence of goiter, increased risk for neurodevelopmental disorders, and is the world's leading cause of intellectual deficits. Iodine nutritional status of a population is assessed by measurements of urinary iodine concentrations which are also used to define, indicate, survey and monitor iodine deficiency and consequently its treatment. Several methods are available for urinary iodine determination. Discussed here are some of the limitations and controversies related to urinary iodine determinations, and recent findings with emphasis on measurements of urinary iodine concentrations in children and during pregnancy.