The Danish investigation on iodine intake and thyroid disease, DanThyr: status and perspectives

A nationwide registry-based observational study of thyroid disease incidence in the Faroe Islands

OBJECTIVE

The occurrence of thyroid disease varies among populations. While the iodine nutrition level of the Faroese seems to have been decreasing over the past decades, there is no systematic evaluation of the thyroid disease pattern in the Faroe Islands. Such knowledge of thyroid disease occurrence in the North Atlantic region may support healthcare planning and prevention. To investigate incidence rates, including subtypes of thyroid diseases, and demographic characteristics of thyroid disease patients in the Faroe Islands, to improve understanding of the patterns and trends of these disorders.

DESIGN AND METHOD

A registry-based observational study was conducted over 10 years, encompassing all adult Faroese individuals.

PATIENTS AND MEASUREMENTS

Health records from general practitioners and hospitals were used to identify incident cases of thyroid diseases. Validation was performed using multiple data sources. The incidence rates were standardised using population data from the middle of the study period 2006-2018.

RESULTS

Among the 1152 individuals diagnosed with thyroid disease, the standardised incidence rates per 100,000 person-years were 55 for hyperthyroidism and 112 for hypothyroidism, and around four times higher in women than in men. Hashimoto's thyroiditis was the dominant cause of hypothyroidism, while Graves' disease was the leading cause of hyperthyroidism. The incidence of hypothyroidism increases with age. A decreasing trend was observed over time for both hypothyroidism and hyperthyroidism.

CONCLUSION

Considering the decrease in iodine nutrition levels over the past decades, we were surprised by the high incidence of autoimmune thyroid disease. The findings highlight the need for continuous monitoring of thyroid disease occurrence in coastal areas of the North Atlantic Ocean.

Agreement between routinely used immunoassays for thyroid function testing in non-pregnant and pregnant adults

OBJECTIVE

Thyroid function tests are common biochemical analyses, and agreement between the routinely used immunoassays is important for diagnosis and monitoring of thyroid disease. Efforts are continuously made to align the biochemical assays, and we aimed to evaluate the agreement between immunoassays used in a clinical laboratory setting among non-pregnant and pregnant adults.

DESIGN

Cross-sectional study.

PARTICIPANTS

Serum samples were obtained from 192 blood donors (non-pregnant adults) and from 86 pregnant women in the North Denmark Region with no known thyroid disease.

MEASUREMENTS

Each sample was used for measurement of thyroid-stimulating hormone (TSH) with the routinely used automatic immunoassays in the regional Departments of Clinical Biochemistry (Alinity, Abbott Laboratories, Cobas, Roche Diagnostics, and Atellica, Siemens Healthineers) and reported as the median with 95% confidence interval (95% CI).

RESULTS

In nonpregnant adults, the level of TSH was higher with Cobas and Atellica than with Alinity as reflected by median (Alinity: 1.39 mIU/L (95% CI: 1.30-1.51 mIU/L); Cobas: 1.57 mIU/L (95% CI: 1.48-1.75 mIU/L); Atellica: 1.74 mIU/L (95% CI: 1.61-1.83 mIU/L)). Similarly, a trend was seen towards higher median TSH with Cobas than with Alinity among pregnant women (Alinity: 1.90 mIU/L (95% CI: 1.37-2.82 mIU/L); Cobas: 2.33 mIU/L (95% CI: 1.69-3.62 mIU/L)).

CONCLUSION

Results of thyroid function tests obtained with different immunoassays were not interchangeable when evaluated among pregnant and non-pregnant adults. The distinct differences are relevant for clinical decision making and emphasize the necessity of clinical laboratory information when different assays are used for diagnosis and monitoring of patients with thyroid disease.

ESPEN practical short micronutrient guideline

BACKGROUND

Trace elements and vitamins, named together micronutrients (MNs), are essential for human metabolism. The importance of MNs in common pathologies is recognized by recent research, with deficiencies significantly impacting the outcome.

OBJECTIVE

This short version of the guideline aims to provide practical recommendations for clinical practice.

METHODS

An extensive search of the literature was conducted in the databases Medline, PubMed, Cochrane, Google Scholar, and CINAHL for the initial guideline. The search focused on physiological data, historical evidence (for papers published before PubMed release in 1996), and observational and/or randomized trials. For each MN, the main functions, optimal analytical methods, impact of inflammation, potential toxicity, and provision during enteral or parenteral nutrition were addressed. The SOP wording was applied for strength of recommendations.

RESULTS

The limited number of interventional trials prevented meta-analysis and led to a low level of evidence for most recommendations. The recommendations underwent a consensus process, which resulted in a percentage of agreement (%): strong consensus required of >90 % of votes. Altogether the guideline proposes 3 general recommendations and specific recommendations for the 26 MNs. Monitoring and management strategies are proposed.

CONCLUSION

This short version of the MN guideline should facilitate handling of the MNs in at-risk diseases, whilst offering practical advice on MN provision and monitoring during nutritional support.

Hyperthyroidism in Danish Pregnant Women During a 20-Year Period

CONTEXT

Hyperthyroidism in pregnancy is a clinical concern, and surveillance of any change in the occurrence of hyperthyroidism in pregnancy is important, especially when a mandatory iodine fortification (IF) program is implemented such as in Denmark in the year 2000.

OBJECTIVE

To investigate any change in the occurrence of hyperthyroidism and the use of antithyroid drugs (ATDs) in Danish pregnant women during a 20-year period before and after the implementation of IF.

METHODS

A nationwide register-based cohort (1997-2016) and 2 birth cohorts with biochemical data (the Danish National Birth Cohort, 1997-2003, and the North Denmark Region Pregnancy Cohort, 2011-2015) were used to study maternal use of ATDs in pregnancy and frequency of early pregnancy biochemical hyperthyroidism during a 20-year period prior to and after the implementation of mandatory IF.

RESULTS

In the nationwide cohort, the adjusted odds ratio (aOR) for treatment with ATDs was 1.51 (95% CI, 1.30-1.74) after mandatory IF (2001-2004) compared with baseline (1997-1999). The increase was more pronounced in the previously moderately iodine-deficient West Denmark (aOR 1.67; 95% CI, 1.36-2.04) than the mildly deficient East Denmark (aOR 1.30; 95% CI, 1.06-1.60) and returned to baseline levels at the end of follow-up in both regions. No time-related difference in early pregnancy biochemical hyperthyroidism was observed.

CONCLUSION

The use of ATDs in Danish pregnant women increased following the implementation of IF and then leveled out. Results comply with observations in the general Danish population and suggest that IF influences the occurrence of autoimmune hyperthyroidism in younger individuals.

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

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

Thyroid function and urinary concentrations of iodine, selenium, and arsenic in vegans, lacto-ovo vegetarians and pescatarians

PURPOSE

Populations following a plant-based diet may be at particular risk of thyroid dysfunction due to low iodine and selenium intakes. The main purpose was to assess thyroid function and urinary concentration of iodine, selenium, and arsenic, in subjects following a vegan, lacto-ovo vegetarian, or pescatarian diet.

METHODS

In Norway, a country without mandatory dietary iodine fortification, 205 adults, following vegan (n = 115), lacto-ovo vegetarian (n = 55) and pescatarian diet (n = 35) were included. Thyroglobulin (Tg), thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), and serum anti-TPO (S-anti-TPO) were measured in a venous blood sample and concentrations of iodine (UIC), creatinine (UCC), selenium, and arsenic were measured from single spot urine samples.

RESULTS

Subclinical hypothyroidism (TSH > 4.0 mU/L) was observed in 3% of subjects. The overall median (p25, p75) Tg was 17 (9, 30) µg/L and vegans had higher Tg compared to pescatarians. Vegans not consuming iodine-containing supplements (n = 43) had higher Tg, than supplement users (n = 72), 27 (11, 44) vs. 16 (8, 25) µg/L and higher fT4, 16 (15, 17) vs. 15 (14, 17) pmol/L, respectively. The overall median UIC was 57 (28, 130) µg/L, all dietary groups had median UIC below WHO thresholds. Median urinary selenium and arsenic concentration was 13 (6, 22) and 3 (2, 8) µg/L, respectively.

CONCLUSION

The prevalence of subclinical hypothyroidism was low and fT4 and fT3 were within the normal range for all dietary groups. Vegans had significantly increased Tg compared to pescatarians.

Hyperthyroidism: A Review

Importance

Overt hyperthyroidism, defined as suppressed thyrotropin (previously thyroid-stimulating hormone) and high concentration of triiodothyronine (T3) and/or free thyroxine (FT4), affects approximately 0.2% to 1.4% of people worldwide. Subclinical hyperthyroidism, defined as low concentrations of thyrotropin and normal concentrations of T3 and FT4, affects approximately 0.7% to 1.4% of people worldwide. Untreated hyperthyroidism can cause cardiac arrhythmias, heart failure, osteoporosis, and adverse pregnancy outcomes. It may lead to unintentional weight loss and is associated with increased mortality.

Observations

The most common cause of hyperthyroidism is Graves disease, with a global prevalence of 2% in women and 0.5% in men. Other causes of hyperthyroidism and thyrotoxicosis include toxic nodules and the thyrotoxic phase of thyroiditis. Common symptoms of thyrotoxicosis include anxiety, insomnia, palpitations, unintentional weight loss, diarrhea, and heat intolerance. Patients with Graves disease may have a diffusely enlarged thyroid gland, stare, or exophthalmos on examination. Patients with toxic nodules (ie, in which thyroid nodules develop autonomous function) may have symptoms from local compression of structures in the neck by the thyroid gland, such as dysphagia, orthopnea, or voice changes. Etiology can typically be established based on clinical presentation, thyroid function tests, and thyrotropin-receptor antibody status. Thyroid scintigraphy is recommended if thyroid nodules are present or the etiology is unclear. Thyrotoxicosis from thyroiditis may be observed if symptomatic or treated with supportive care. Treatment options for overt hyperthyroidism from autonomous thyroid nodules or Graves disease include antithyroid drugs, radioactive iodine ablation, and surgery. Treatment for subclinical hyperthyroidism is recommended for patients at highest risk of osteoporosis and cardiovascular disease, such as those older than 65 years or with persistent serum thyrotropin level less than 0.1 mIU/L.

Conclusions and Relevance

Hyperthyroidism affects 2.5% of adults worldwide and is associated with osteoporosis, heart disease, and increased mortality. First-line treatments are antithyroid drugs, thyroid surgery, and radioactive iodine treatment. Treatment choices should be individualized and patient centered.

Invited review: Iodine level in dairy products-A feed-to-fork overview

The theme of iodine in the dairy sector is of particular interest due to the involvement and the interconnection of several stakeholders along the dairy food chain. Iodine plays a fundamental role in animal nutrition and physiology, and in cattle it is an essential micronutrient during lactation and for fetal development and the calf's growth. Its correct use in food supplementation is crucial to guarantee the animal's recommended daily requirement to avoid excess intake and long-term toxicity. Milk iodine is fundamental for public health, being one of the major sources of iodine in Mediterranean and Western diets. Public authorities and the scientific community have made great efforts to address how and to what extent different drivers may affect milk iodine concentration. The scientific literature concurs that the amount of iodine administered through animal feed and mineral supplements is the most important factor affecting its concentration in milk of most common dairy species. Additionally, farming practices related to milking (e.g., use of iodized teat sanitizers), herd management (e.g., pasture vs. confinement), and other environmental factors (e.g., seasonality) have been identified as sources of variation of milk iodine concentration. Overall, the aim of this review is to provide a multilevel overview on the mechanisms that contribute to the iodine concentration of milk and dairy products.

Neutrophil-To-Lymphocyte Ratio is Associated With the Proportion of Poorly Differentiated Components in Papillary Thyroid Carcinoma

INTRODUCTION

Diagnosis of poorly differentiated thyroid cancer (PDTC) requires ≥ 50% of poorly differentiated components (PDC) in Japan. However, the optimal cutoff percentage of PDC for PDTC diagnosis remains controversial. Although high neutrophil-to-lymphocyte ratio (NLR) correlates with the aggressiveness of papillary thyroid cancer (PTC), whether NLR is associated with the proportion of PDC in PTC remains unstudied.

MATERIALS AND METHODS

Patients with the pure PTC (n = 664), PTC with < 50% PDC (n = 19), or PTC with ≥ 50% PDC (n = 26) who underwent surgery were retrospectively analyzed. Twelve-year disease-specific survival and preoperative NLR were compared among these groups.

RESULTS

Twenty seven patients died from thyroid cancer. The PTC with ≥ 50% PDC group (80.7%) showed significantly worse 12-year disease-specific survival than the pure PTC group (97.2%) (P < 0.001); however, the < 50% PDC group (94.7%) did not (P = 0.91). The PTC with ≥ 50% PDC group had a significantly higher NLR than the pure PTC (P < 0.001) and the PTC with < 50% PDC groups (P < 0.001), whereas there was no significant difference in the NLR between the pure PTC and the PTC with < 50% PDC groups (P = 0.48).

CONCLUSIONS

PTC with ≥ 50% PDC is more aggressive than either pure PTC or PTC with < 50% PDC, and NLR potentially reflects the PDC proportion. These results support the validity of 50% PDC as a cut-off for PDTC diagnosis and indicate the utility of NLR as a biomarker for PDC proportion.

Iodine status in Danish pregnant women after an increase in iodine fortification

OBJECTIVE

Iodine fortification programmes are implemented in many countries and often associated with an increase in population iodine intake. However, the initial attempt may not be sufficient and in Denmark the level of iodine added to salt was increased in 2019. Sparse evidence is available on the impact of such modification in iodine fortification. The aim of this study was to evaluate iodine status in Danish pregnant women in 2021 after this increase in iodine fortification and compare to iodine status in 2012.

DESIGN

Cross-sectional study.

PATIENTS

Pregnant women in the North Denmark Region referred for routine obstetric ultrasound in 2021.

MEASUREMENTS

Participants filled out a questionnaire and delivered a spot urine. Median urinary iodine concentration (UIC) was calculated and assessed according to the recommended range in pregnancy (150-249 µg/L).

RESULTS

Altogether 147 pregnant women were included and 88% used iodine-containing supplements. Median UIC was overall 77 µg/L [95% confidence interval (CI): 61-96 µg/L], which was lower than in 2012 (101 µg/L [95% CI: 89-111 µg/L]) (p < 0.001). Considering sources of iodine intake in pregnancy, lower daily intake of dairy products (p = 0.008) and bread (p < 0.001) and a lower content of iodine in the supplement used (p < 0.001) was seen in 2021 compared to 2012.

CONCLUSION

Despite an increase in iodine fortification and frequent use of iodine-containing supplements, iodine status in pregnant women in the North Denmark Region was insufficient. Results call for continued monitoring and attention to ensure adequate iodine status during pregnancy in Denmark.

Maternal Health, Pregnancy and Offspring Factors, and Maternal Thyroid Cancer Risk: A Nordic Population-Based Registry Study

Thyroid cancer incidence is higher in women than men, especially during the reproductive years, for reasons that remain poorly understood. Using population-based registry data from 4 Nordic countries through 2015, we examined associations of perinatal characteristics with risk of maternal thyroid cancer. Cases were women diagnosed with thyroid cancer ≥2 years after last birth (n = 7,425, 83% papillary). Cases were matched to controls (n = 67,903) by mother's birth year, country, and county of residence. Odds ratios (ORs) were estimated using conditional logistic regression models adjusting for parity. Older age at first pregnancy, postpartum hemorrhage (OR = 1.18, 95% (confidence interval) CI: 1.08, 1.29), and benign thyroid conditions (ORs ranging from 1.64 for hypothyroidism to 10.35 for thyroid neoplasms) were associated with increased thyroid cancer risk, as were higher offspring birth weight (per 1-kg increase, OR = 1.17, 95% CI: 1.12, 1.22) and higher likelihood of offspring being large for gestational age (OR = 1.26, 95% CI: 1.11, 1.43). Unmarried/noncohabiting status (OR = 0.91, 95% CI: 0.84, 0.98), maternal smoking (OR = 0.75, 95% CI: 0.67, 0.84), and preterm birth (OR = 0.90, 95% CI: 0.83, 0.98) were associated with reduced risk. Several factors (e.g., older age at first pregnancy, maternal smoking, goiter, benign neoplasms, postpartum hemorrhage, hyperemesis gravidarum, and neonatal jaundice) were associated with advanced thyroid cancer. These findings suggest that some perinatal exposures may influence maternal thyroid cancer risk.

Iodine nutrition with North Atlantic living: the Faroese adolescents

Iodine nutrition is critical for human health. While iodine excretion was low within the recommended range among adult Faroese, younger generations tend to abandon local foods. Such changes raise a concern about iodine intake, which led us to perform this first study of iodine nutrition among teenagers in the North Atlantic islands. We used samples from a nationwide collection of urine samples in 14-year-olds following iodine fortification of salt in 2000. Urine was analysed for iodine and creatinine to adjust for dilution by iodine/creatinine, and a food frequency questionnaire was used to record the intake of iodine-rich foods. The 129 participants yielded a 90 % precision of the estimated iodine nutrition level. The median urinary iodine concentration (UIC) was 166 μg/l (bootstrapped 95 % confidence interval 156–184 μg/l). The median creatinine-adjusted UIC was 132 μg/g (bootstrapped 95 % CI 120–138 μg/g). Fish and whale meat dinners were more frequent among residents of villages compared with the capital: median fish dinners, 3 v. 2 per week (P = 0⋅001), and whale meat, 1 v. 0⋅4 per month (P < 0⋅001). UIC decreased with fewer fish dinners (P = 0⋅03). Our study demonstrated that Faroese teenagers were iodine-replete. The changing dietary habits emphasise the need for continuous monitoring of iodine nutrition and surveying iodine deficiency disorders.

ESPEN micronutrient guideline

BACKGROUND

Trace elements and vitamins, named together micronutrients (MNs), are essential for human metabolism. Recent research has shown the importance of MNs in common pathologies, with significant deficiencies impacting the outcome.

OBJECTIVE

This guideline aims to provide information for daily clinical nutrition practice regarding assessment of MN status, monitoring, and prescription. It proposes a consensus terminology, since many words are used imprecisely, resulting in confusion. This is particularly true for the words "deficiency", "repletion", "complement", and "supplement".

METHODS

The expert group attempted to apply the 2015 standard operating procedures (SOP) for ESPEN which focuses on disease. However, this approach could not be applied due to the multiple diseases requiring clinical nutrition resulting in one text for each MN, rather than for diseases. An extensive search of the literature was conducted in the databases Medline, PubMed, Cochrane, Google Scholar, and CINAHL. The search focused on physiological data, historical evidence (published before PubMed release in 1996), and observational and/or randomized trials. For each MN, the main functions, optimal analytical methods, impact of inflammation, potential toxicity, and provision during enteral or parenteral nutrition were addressed. The SOP wording was applied for strength of recommendations.

RESULTS

There was a limited number of interventional trials, preventing meta-analysis and leading to a low level of evidence. The recommendations underwent a consensus process, which resulted in a percentage of agreement (%): strong consensus required of >90% of votes. Altogether the guideline proposes sets of recommendations for 26 MNs, resulting in 170 single recommendations. Critical MNs were identified with deficiencies being present in numerous acute and chronic diseases. Monitoring and management strategies are proposed.

CONCLUSION

This guideline should enable addressing suboptimal and deficient status of a bundle of MNs in at-risk diseases. In particular, it offers practical advice on MN provision and monitoring during nutritional support.

Iodine deficiency is associated with increased thyroid hormone sensitivity in individuals with elevated TSH

Objective

Central sensitivity of thyroid hormone refers to the sensitivity of hypothalamic-pituitary-thyroid (HPT) axis to the change in circulating free thyroxine (fT4). A complex relationship exists between thyroxine levels and iodine nutritional status. To explore the relationship between thyroid hormone sensitivity and iodine nutritional status in elevated thyrotropin (TSH), we used national data to assess the relationship between thyroid hormone sensitivity and iodine nutritional status with contrasting demographic characteristics in China.

Methods

We enrolled 12,197 participants with TSH > 4.2 mIU/L from China. Serum and urine samples were collected, and we measured serum fT4, TSH, thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) levels and urinary iodine concentration (UIC). The thyroid hormone sensitivity indices were calculated based on fT4 and TSH. The thyroid feedback quantile-based index (TFQI) is a new index to reflect thyroid hormone sensitivity. Higher TFQI quartiles indicated lower thyroid hormone sensitivity.

Results

The odds ratios (ORs) for the fourth versus first TFQI quartile were 0.84 (95% CI 0.72-0.99) for iodine deficiency, 1.24 (95% CI 1.05-1.47) for TPOAb+, and 0.44 (95% CI 0.40-0.50) for females. The OR of the fourth and first TFQI quartiles for age <30 years and >60 years was 2.09 (95% CI 1.82-2.41) and 1.19 (95% CI 1.05-1.36), respectively (P < 0.05). Other thyroid sensitivity indices also yielded similar results.

Conclusion

Thyroid hormone sensitivity and age have a U-shaped association in individuals with elevated TSH. Increased thyroid hormone sensitivity is associated with iodine deficiency and the female gender. Decreased thyroid hormone sensitivity is associated with TPOAb+. These findings are interesting and potentially useful for understanding the interaction between iodine nutrition and the hypothalamic-pituitary-thyroid axis.

Effects of geographical factors on reference values of the thyroid stimulating hormone in healthy adults in China and its clinical significance

The thyroid stimulating hormone (TSH) plays an important regulatory role in maintaining normal function of the thyroid gland. The purpose of this study was to explore the geographical, spatial distribution of TSH normal values in healthy Chinese adults to be used for the formulation of a standard reference. TSH values of 9321 healthy adults from 120 cities in China were collected together with 24 topographic, climatic and soil variables and used for the determination of spatial, significant relationships between TSH and these geographical factors by correlation analysis. Eleven significant factors were extracted and subjected to ridge regression and construction of vector machine models. The predicted values were tested for normality, with the disjunctive Kriging interpolation method used for geographical distribution. The values found showed a spatial pattern of higher values in the North and west but lower in the South and east We concluded that ridge regression models are useful for this kind of investigations and that certain geographical factors determine the level of TSH in healthy adults in a large expanse of land where topography, climate and soil indices vary.

Risk–Benefit Assessment of an Increase in the Iodine Fortification Level of Foods in Denmark—A Pilot Study

Iodine deficiency is one of the most common nutritional disorders worldwide. In Denmark, the mandatory iodine fortification of salt of 13 ppm was introduced in 2000 to eradicate mild to moderate iodine deficiency and the fortification level was increased to 20 ppm in 2019. However, the optimal iodine intake is a narrow interval, and the risk of disease increases with intakes both below and above this interval. In this study, we quantified the risk–benefit balance in the Danish adult population by increasing the mandatory fortification level. We applied a risk–benefit assessment approach in which population-level iodine intakes before and after the increase in fortification were integrated with epidemiological evidence of the association between iodine nutrition status and risk of relevant diseases to estimate the number of cases caused or prevented and estimated health impact in terms of disability-adjusted life years (DALY). We estimated an overall beneficial health impact and prevention of 34.9 (95% UI: −51.6; −21.7) DALY per 100,000 adults in the population annually with the increase in fortification level. Prevention of low IQ in children due to maternal iodine deficiency was the primary contributor to overall health gain. The gain in healthy life years comes at the expense of extra cases of goiter due to iodine excess. Due to lack of data, hypo- and hyperthyroidism related to iodine status were not included. Neither were children as a population group. Because of this, as well as uncertainties inherent in the model and data used, results should be interpreted with caution. We argue that nation-specific, quantitative assessments of the public health impact of fortification programs provide transparent, evidence-based decision support. Future research should aim to enable the inclusion of all relevant health effects as well as children in the assessment.

Assessment of iodine fortification of salt in the Danish population

PURPOSE

We assessed the effect of the current iodine fortification level (20 µg/g household salt and salt included in bread and bakery products) on inadequate and excessive intake in the general Danish population. Intake models with/without the contribution from food supplements and effects of excluding specific food groups were evaluated.

METHOD

Data from the Danish National Survey of Dietary Habits and Physical Activity in 2011-13 (N = 3946, aged 4-75 years) stratified by age-group and sex were used to estimate habitual dietary iodine intakes, and compared with established dietary reference values.

RESULTS

The proportion with an estimated inadequate iodine intake was ≤ 3% for males and ≤ 5% for females, except for 15-17-year-old girls, where the probable prevalence of an inadequate intake was 11%. Including the contribution from food supplements gave similar results (10%). High intakes (as defined by 95th percentile) from food sources generally did not exceed the tolerable upper intake level (UL). However, for the youngest age-groups (4-6-year-old boys/girls and 7-10-year-old boys), the 95th percentiles exceeded the UL with 11%, 4% and 7%, respectively, when food supplements were included in the estimates. Especially exclusion of dairy products and bread led to an inadequate intake for both boys and girls.

CONCLUSION

The current fortification level may provide an inadequate iodine intake for some females and on the other hand lead to excessive intakes in the youngest age-groups. The study shows the importance of choosing iodine-rich alternatives when excluding major sources of iodine in the Danish diet.

Thyroid dysfunction in Greece: Results from the national health examination survey EMENO

Background

Nationwide data on thyroid disease prevalence in Greece is lacking. Using the national health examination survey EMENO data resources, we aimed to estimate the prevalence of hypothyroidism and hyperthyroidism and associated risk factors in adults living in Greece.

Methods

A random sample of the adults (≥18 years) living in Greece was drawn by multi-stage stratified random sampling based on the 2011 census. During home visits, trained interviewers administered a standardized questionnaire to study participants. All participants answered questions concerning demographic parameters (e.g., age, sex, degree of urbanization, income) and questions concerning smoking habits, alcohol, dietary habits and psychological parameters such as anxiety and thyroid disease. Weighted logistic regression models were fitted to assess factors associated with thyroid disease.

Results

In total, 6006 individuals were recruited in the Greek Health Examination Survey EMENO (response rate 72%) of whom 5981 were eligible for this study. The prevalence of thyroid disease was 9%, where 0.4% was related to hyperthyroidism and 8.6% to hypothyroidism. The prevalence of thyroid disease was higher in women (14.9%) than men (2.7%) (p<0.001). The highest rates of thyroid disease were observed in former iodine-deficient areas. A decrease in the prevalence of thyroidopathies with increasing alcohol consumption was found. Thyroid disease was associated with anxiety in men. Multivariable regression analysis showed that age, geographic area, and smoking were related to thyroid disease.

Conclusion

The prevalence of thyroid disease in Greece is higher in women. Age, habits, and characteristics of geographic areas determine the distribution of thyroidopathies in Greece.

Raised mortality in old adults with a history of hyperthyroidism following iodine fortification

OBJECTIVE

A transient rise in the occurrence of hyperthyroidism ensued the introduction of iodine fortification (IF) of salt in Denmark. Older adults are at risk of complications to hyperthyroidism that could prove fatal to vulnerable individuals. We evaluated the association between thyroid function and mortality in older adults before and after nationwide implementation of IF.

DESIGN

Retrospective cohort study.

PATIENTS

All 68-year-olds from the general population in the city of Randers were invited to participate in a clinical study in 1988 and followed until death, emigration or end of study (31 December 2017) using Danish registries.

MEASUREMENTS

Baseline measures comprised of a questionnaire, physical examination and blood and urine samples. Kaplan-Meier survival curves and Cox regression were used to determine the association between thyroid function and death before and after IF. Time-stratification of results before and after IF was employed due to violation of proportional hazards assumptions in Cox regression.

RESULTS

Median urinary iodine concentration was 42 µg/L at baseline consistent with moderate iodine deficiency. Hyperthyroidism (thyrotropin < 0.4 mIU/L) occurred in 37 (9.1%) participants. Kaplan-Meier survival curves showed an increase in mortality among participants with hyperthyroidism after IF. There was no significant association between hyperthyroidism and mortality before IF compared to euthyroid participants, but after IF hyperthyroid subjects had an increased mortality (adjusted hazard ratio: 2.22, 95% confidence interval: 1.44-3.44).

CONCLUSIONS

IF was associated with raised mortality among older adults with a history of hyperthyroidism and moderate iodine deficiency. Our results highlight the need for cautious iodine supplementation and for monitoring of IF.

Disruption by stealth - Interference of endocrine disrupting chemicals on hormonal crosstalk with thyroid axis function in humans and other animals

Thyroid hormones (THs) are important regulators of growth, development, and homeostasis of all vertebrates. There are many environmental contaminants that are known to disrupt TH action, yet their mechanisms are only partially understood. While the effects of Endocrine Disrupting Chemicals (EDCs) are mostly studied as "hormone system silos", the present critical review highlights the complexity of EDCs interfering with TH function through their interactions with other hormonal axes involved in reproduction, stress, and energy metabolism. The impact of EDCs on components that are shared between hormone signaling pathways or intersect between pathways can thus extend beyond the molecular ramifications to cellular, physiological, behavioral, and whole-body consequences for exposed organisms. The comparatively more extensive studies conducted in mammalian models provides encouraging support for expanded investigation and highlight the paucity of data generated in other non-mammalian vertebrate classes. As greater genomics-based resources become available across vertebrate classes, better identification and delineation of EDC effects, modes of action, and identification of effective biomarkers suitable for HPT disruption is possible. EDC-derived effects are likely to cascade into a plurality of physiological effects far more complex than the few variables tested within any research studies. The field should move towards understanding a system of hormonal systems' interactions rather than maintaining hormone system silos.

Relationship Between Thyroid Hormonal Status in Patients with a Hypothyroid Form of Hashimoto's Thyroiditis and Iodine Concentrations in Drinking Water

The current study aimed to identify correlative and regressive dependencies between the water iodine concentration and the levels of TSH (thyroid-stimulating hormone), thyroglobulin antibodies (TgAbs), and thyroid peroxidase (TPOAb) in the serum of 168 in patients (34 men and 134 women) with a hypothyroid form of Hashimoto's thyroiditis who use water from the supply network and individual wells. Based on the water iodine concentration, low and moderate degrees of iodine endemia in the location of the patients were determined. In the groups of men and women using water from different water supply sources, there were direct correlations between the water iodine concentrations and the TgAbs and TPOAb titers as well as an inverse dependence between iodine and TSH levels. Multivariate regressive analysis indicated that TgAb and TSH in the group of women using water from a supply network and TPOAb titers in the group of women using well water were independent factors associated with water iodine concentrations. Statistically significant correlations and regressive dependencies between the water iodine concentrations and the biomarkers of the thyroid status of the patients indicate the risk of Hashimoto's thyroiditis progression, especially among women with additional iodine intake.

Does Subclinical Hypothyroidism Add Any Symptoms? Evidence from a Danish Population-Based Study

BACKGROUND

Few studies have scrutinized the spectrum of symptoms in subclinical hypothyroidism.

METHODS

From 3 Danish Investigation on Iodine Intake and Thyroid Diseases (DanThyr) cross-sectional surveys performed in the period 1997 to 2005, a total of 8903 subjects participated in a comprehensive investigation including blood samples and questionnaires on previous diseases, smoking habits, alcohol intake, and education. From the 3 surveys we included patients with subclinical hypothyroidism (n = 376) and euthyroid controls (n = 7619). We explored to what extent patients with subclinical hypothyroidism reported 13 previously identified hypothyroidism-associated symptoms (tiredness, dry skin, mood lability, constipation, palpitations, restlessness, shortness of breath, wheezing, globus sensation, difficulty swallowing, hair loss, dizziness/vertigo, and anterior neck pain). In various uni- and multivariate regression models we searched for circumstances predicting why some patients have more complaints than others.

RESULTS

Subclinically hypothyroid patients did not report higher hypothyroidism score [(median, interquartile range), 2 (0-4) vs 2 (0-4), P = .25] compared with euthyroid controls. Within the group of subclinical hypothyroid patients, comorbidity had the highest impact on symptoms (tiredness, shortness of breath, wheezing; all P < .001); TSH level had no impact on symptom score; and younger age was accompanied by higher mental burden (tiredness, P < .001; mood lability, P < .001; restlessness, P = .012), whereas shortness of breath was associated with high body mass index (P < .001) and smoking (P = .007).

CONCLUSION

Patients with a thyroid function test suggesting subclinical hypothyroidism do not experience thyroid disease-related symptoms more often than euthyroid subjects. In subclinical hypothyroidism, clinicians should focus on concomitant diseases rather than expecting symptomatic relief following levothyroxine substitution.

MicroRNA expression profiles of the thyroid after goiter formation and involution in rats under different iodine regimens

BACKGROUND

Thyroid damage occurs during experimental iodine-deficient goiter and involution with iodine supplementation. This study investigated the dynamic microRNAs (miRNAs) expression profiles in iodine-deficient thyroids during adequate and excessive iodine supplementation.

METHODS

Twenty-four female Wistar rats were randomly divided into control, low-iodine (LI), LI-1I, and LI-2I groups. The LI-1I and LI-2I groups were fed a LI diet for 12 weeks, followed by a onefold (adequate) or twofold (excessive) physiological dose of iodine for 4 weeks to induce involution. The miRNA expression profiles were evaluated and the potential functions of the differentially expressed miRNAs identified were explored.

RESULTS

In the LI group, 20 miRNAs were downregulated and 8 were upregulated. After involution, 21 miRNAs recovered to the control group levels in the LI-1I group, which was more than the 17 that recovered in the LI-2I group. In addition, 8 new differentially expressed miRNAs were identified in the LI-1I group, which was less than the 13 found in the LI-2I group. Bioinformatics analyses indicated that all differentially expressed miRNAs were involved in different processes and pathways, such as autoimmune thyroid disease and the Ras signaling pathway.

CONCLUSION

Differentially expressed miRNAs are involved in iodine-deficient goiter formation and involution. Supplementation with adequate, not excessive, iodine may be more beneficial to restore homeostasis.

Iodine nutrition optimization: are there risks for thyroid autoimmunity?

Iodine deficiency is still the main cause of preventable thyroid disorders, worldwide. To optimize iodine intake, programs of voluntary or mandatory iodization of salt have been implemented in several iodine-deficient countries and iodine sufficiency has been achieved in many. Despite the clear beneficial effects on thyroid health, some concerns have been raised on the presumed detriment of iodine prophylaxis on thyroid autoimmunity. Very recent studies aimed at evaluating the long-term consequences of iodine supplementation on thyroid autoimmunity and related dysfunction, have clearly demonstrated that the early post-iodization increase in thyroid antibody positivity is largely transient and not clinically relevant, since the prevalence of overt thyroid dysfunction has remained reassuring low over two decades. The recommended iodine intake is therefore safe with regard to thyroid autoimmunity, the benefits largely outweighing the risks in a population with a stable median iodine concentration not exceeding 300 μg/L. Thus, a possible increase in thyroid autoimmunity should not represent a limitation to promoting iodine supplementation in the general population, also taking into account the steady rise in prevalence of autoimmune disorders which has occurred in the last few decades because of environmental factors other than iodine.

Iodine nutrition among the adult population of the Faroe Islands: a population-based study

The WHO recommends monitoring iodine status in all populations with median urinary iodine concentration (UIC) below 100 µg/l suggesting iodine deficiency. There are no data on the iodine intake among the population of the Faroe Islands. This study aimed to provide data on iodine nutrition in a representative sample of the general adult population from the Faroe Islands. We conducted a population-based cross-sectional survey in 2011–2012 and measured iodine in urine from 491 participants (294/197 men/women) using the ceri/arsen method after alkaline ashing. Participants include about 100 subjects in each of four adult decades and included participants from both the capital city and villages. The median UIC was low within the recommended range 101 µg/l (range 21–1870 µg/l). No samples were in the range suggesting severe iodine deficiency, but half of the samples were in the range of just adequate or mildly insufficient iodine intake with UIC markedly lower in women than in men (86 v. 115 µg/l; P < 0·001). Intake of fish and whale meals affected the UIC. In conclusion, nearly half of the population had an iodine excretion in the range of borderline or mild iodine deficiency. The lowest iodine nutrition level among Faroese women is a concern as it may extend to pregnancy with increased demands on iodine nutrition. In addition, we found that large variations and the intermittently excessive iodine intakes warrant follow-up on thyroid function in the population of the Faroe Islands.

Evaluation of Iodine Status among Korean Patients with Papillary Thyroid Cancer Using Dietary and Urinary Iodine

BACKGROUND

Concerns have been raised regarding thyroid disorders caused by excessive iodine in Koreans, who have iodine-rich diets. This study evaluated iodine status using dietary iodine intake and urinary iodine in papillary thyroid cancer (PTC) patients.

METHODS

Dietary data of PTC patients were assessed using a 24-hour recall and food frequency questionnaire (FFQ), and urinary iodine concentrations (UICs) were also obtained. To compare the iodine status of PTC patients, Korean adults with or without thyroid disease from the Korea National Health and Nutrition Examination Survey, which had 24-hour recall data and urinary iodine measurements, were analyzed.

RESULTS

The median daily iodine intake by 24-hour recall was 341.7 μg/day in PTC patients, similar to the levels of other Korean adults. Based on UICs, the prevalence of excessive iodine was 54.4% in PTC patients, which was similar to the prevalence among subjects with thyroid disease (55.4%) but slightly higher than that in subjects without thyroid disease (47.7%). Based on dietary iodine by 24-hour recall, the prevalence of excessive iodine intake was 7.2%, which was higher than that among subjects with (4.4%) or without (3.9%) thyroid disease. The dietary iodine intake based on 24-hour recall was closely correlated with the UIC (r=0.4826) in PTC patients, but dietary iodine by FFQ was not significantly correlated with either 24-hour recall or UIC-based dietary iodine.

CONCLUSION

Excessive iodine intake was more common in PTC patients than in subjects without thyroid disease. Further longitudinal research is necessary to elucidate the role of dietary iodine in PTC.

[Dynamics of epidemiological indicators of thyroid pathology in the population of the Russian Federation: analytical report for the period 2009-2018]

ОБОСНОВАНИЕ. Уровень потребления йода населением во многом определяет спектр тиреоидной патологии. На сегодняшний день в РФ йододефицитные заболевания (ЙДЗ) занимают лидирующие позиции в структуре всех заболеваний щитовидной железы (ЩЖ). Хронический дефицит йода (ЙД) приводит к неблагоприятным последствиям для здоровья и существенным экономическим затратам на их устранение в масштабах страны. Кроме того, спектр тиреоидной патологии в условиях ЙД не ограничивается проблемой ЙД, и изучение остальных заболеваний ЩЖ также представляет интерес.ЦЕЛЬ. Проанализировать динамику основных эпидемиологических показателей ЙДЗ и других заболеваний ЩЖ у всего населения РФ за период 2009–2018 гг., используя данные официальной государственной статистики.МЕТОДЫ. Проанализированы заболеваемость и распространенность заболеваний ЩЖ у всего населения РФ с использованием данных официальной государственной статистики. Использованы статистические формы №63 МЗ СР РФ «Сведения о заболеваниях, связанных с микронутриентной недостаточностью» и №12 «Сведения о числе заболеваний, зарегистрированных у больных, проживающих в районе обслуживания лечебного учреждения, РОССТАТ». Анализируемый период — 2009–2018 гг. Для оценки динамики распространенности и заболеваемости были построены линейные регрессионные модели.РЕЗУЛЬТАТЫ. Данные проанализированы в соответствии с представленной в статистической отчетности структурой заболеваний: зоб, тиреоидит, гипотиреоз, тиреотоксикоз, синдром врожденной йодной недостаточности. За десятилетний период 2009–2018 гг. отмечается статистически значимый рост распространенности различных форм зоба, тиреотоксикоза, синдрома врожденной йодной недостаточности у всего населения РФ. В течение периода наблюдения выявлен рост заболеваемости тиреотоксикозом. В отношении заболеваемости синдромом врожденной йодной недостаточности выявлена лишь тенденция к росту. Несмотря на то что в течение периода наблюдения число новых случаев различных форм зоба уменьшилось, распространенность зоба среди населения РФ остается высокой: 1,2% населения к 1 января 2019 г. В отношении тиреоидита выявлен статистически значимый рост распространенности и заболеваемости, что может быть связано с ростом аутоиммунной патологии, совершенствованием уровня диагностики, а также, в некоторых случаях, с гипердиагностикой (например, при постановке диагноза аутоиммунного тиреоидита у лиц с бессимптомным носительством антитиреоидных антител). Существующие на сегодняшний день подходы к йодной профилактике недостаточно эффективны.ЗАКЛЮЧЕНИЕ. Результаты проведенного анализа свидетельствуют преимущественно о росте распространенности тиреоидной патологии среди населения РФ на фоне проводимых региональных мероприятий. Проблема ЙДЗ остается нерешенной, что диктует необходимость внедрения всеобщего обязательного йодирования соли на территории РФ.

Long-Term Follow-Up of Thyroid Incidentalomas Visualized with 18F-Fluorodeoxyglucose Positron Emission Tomography-Impact of Thyroid Scintigraphy in the Diagnostic Work-Up

Our objective was to evaluate the frequency of malignancy in incidental thyroidal uptake on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in a cohort of Danish patients, and furthermore to evaluate the impact of thyroid scinti-graphy in the diagnostic work-up. All whole-body PET/CT reports from 1 January 2010 to 31 December 2013 were retrospectively reviewed and further analyzed if visually increased thyroidal FDG uptake was reported. Patient electronic files were searched for further thyroid evaluation. Of 13,195 18F-FDG-PET/CT scans in 9114 patients, 312 PET/CT reports mentioned incidental thyroid FDG-uptake, and 279 patients were included in the study (3.1%). The thyroid was further investigated in 137 patients (49%), and 75 patients underwent thyroid scintigraphy. A total of 57 patients had a thyroid biopsy and 21 proceeded to surgery. Surgical specimens displayed malignancy in 10 cases, and one thyroid malignancy was found by autopsy. Hence, 11 patients were diagnosed with thyroid malignancies among 279 patients with incidental thyroid 18F-FDG uptake (3.9%). In 34 patients, a biopsy was avoided due to the results of the thyroid scintigraphy. We conclude that patients with thyroid incidentalomas can benefit from further diagnostic work-up including a thyroid scintigraphy.

Relationship between thyroid disorders and uterine fibroids among reproductive-age women

Uterine fibroids and thyroid nodules, both of which are crucially affected by estrogen, are common diseases among reproductive-age women. However, little attention has been paid to the association between the two diseases. This retrospective case-control study aimed to assess the relationships among thyroid nodules, thyroid function and uterine fibroids in China. We reviewed the electronic records of 853 reproductive-age women who attended health check-ups at the Second Affiliated Hospital of Wenzhou Medical University from July 1st, 2017, to June 30th, 2018. All subjects received transvaginal pelvic ultrasound, thyroid ultrasound, thyroid function, and other laboratory tests. We found that the prevalence of thyroid nodules in subjects with uterine fibroids was remarkably higher than that in subjects without fibroids. The proportion of thyroid nodules ≥1 cm in subjects with uterine fibroids was significantly higher than that in subjects without fibroids. Women with thyroid nodules had a higher proportion of multiple uterine fibroids than women without thyroid nodules. Among the parameters of thyroid function, the only statistically significant parameter was total triiodothyronine, i.e., women with uterine fibroids had lower total triiodothyronine levels than unaffected controls; however, the total triiodothyronine levels were within the normal ranges. Moreover, no significant difference was noted in thyroid hormone status between subjects with and without uterine fibroids. Our findings suggest that thyroid nodules are positively correlated with uterine fibroids among reproductive-age women in China. Further studies are needed to confirm this association and fully understand the common pathogenetic mechanism underlying the association between uterine fibroids and thyroid nodules.

Effects of Two Weekly Servings of Cod for 16 Weeks in Pregnancy on Maternal Iodine Status and Infant Neurodevelopment: Mommy's Food, a Randomized-Controlled Trial

Background: Mild-to-moderate iodine deficiency is still present in many countries, particularly in pregnant women. Observational studies suggest that mild-to-moderate iodine deficiency during pregnancy may be associated with impaired thyroid function and child neurodevelopment. Randomized-controlled food trials to increase iodine status are scarce. We assessed the impact of an increased intake of cod during pregnancy on maternal iodine status and infant neurodevelopment. Methods: In this randomized-controlled trial, pregnant women in Bergen, Norway, recruited through Haukeland University Hospital, were randomly assigned (1:1) to an intervention of 200 g of cod twice a week for 16 weeks (gestational week 20-36) or to continue with their standard diet (control group). Randomization was done by lottery. Primary outcome was urinary iodine concentration (UIC) (spot samples from six consecutive days) measured postintervention. Secondary outcome was infant neurodevelopment assessed by the cognitive, language, and motor scales of the Bayley Scales of Infant and Toddler Developmental third edition (Bayley-III) at 11 months of age. In addition, maternal thyroid function was measured (thyrotropin [TSH], free triiodothyronine [fT3], free thyroxine [fT4]) at baseline and postintervention. Results: Between January 2016 until February 2017, 137 women were recruited. Postintervention UIC was higher in the intervention group (n = 61) [median (interquartile range, IQR) 98 (64-145) μg/L], compared with control (n = 61) [median (IQR) 73 (52-120) μg/L] (p = 0.028), also after adjusting for baseline UIC (p = 0.048). Infants of mothers in the intervention group had a lower cognitive composite score on the Bayley-III compared with the control group (p = 0.045). There were no group differences in the Bayley III language- or motor composite scores. Maternal thyroid hormones (TSH, fT3, fT4) did not differ between the groups postintervention. Conclusions: Increased cod intake during pregnancy improved the iodine status in women with mild-to-moderate iodine deficiency, however, did not affect thyroid function. The negative effect on cognition should be followed up to assess whether this is a stable effect over time. More studies are warranted to enable good health advice on iodine nutrition in pregnancy. ClinicalTrials.gov NCT02610959. Registered November 20, 2015.

Hyperthyroidism Prevalence in China After Universal Salt Iodization

BACKGROUND

Universal salt iodization (USI) was implemented in mainland China in 1996. The prevalence of hyperthyroidism and its risk factors now require examination.

METHODS

Data were acquired from a nationwide Thyroid, Iodine, and Diabetes Epidemiological survey (TIDE 2015-2017) of 78,470 subjects from 31 provinces. Iodine status, and thyroid hormones and antibodies were measured.

RESULTS

After two decades of USI, the prevalence of overt hyperthyroidism (OH), Graves' disease (GD), severe subclinical hyperthyroidism (severe SCH), and mild subclinical hyperthyroidism (mild SCH) in mainland China was 0.78%, 0.53%, 0.22%, and 0.22%, respectively. OH and GD prevalence were higher in women than in men (OH: 1.16% vs. 0.64%, P<0.001; GD: 0.65% vs. 0.37%, P<0.001).Prevalence was significantly decreased after 60 years-of-age compared with 30-39 years-of-age (OH:0.61% vs. 0.81%, P<0.001; GD: 0.38% vs. 0.57%, P<0.001).Excessive iodine(EI) and deficient iodine(DI) were both related to increased prevalence of OH (odds ratio [OR] 2.09, 95% confidence interval [CI] 1.68-2.59; OR1.35, 95%CI 1.07-1.72, respectively); however, only deficient iodine was associated with increased prevalence of GD (OR1.67, 95%CI 1.30-2.15). Increased thyroid peroxidase antibody and thyroglobulin antibody levels were significantly associated with prevalence of OH and GD, but not severe SCH and mild SCH. Although hyperthyroidism was more prevalent in women, the association disappeared after adjusting for other factors such as antibody levels.

CONCLUSION

OH and GD prevalences in mainland China are stable after two decades of USI. Iodine deficiency, elevated thyroid antibody levels, and middle age are the main risk factors for OH and GD. The severe SCH population, rather than the mild SCH population, shows similar characteristics to the OH population.

The economic impact of prevention, monitoring and treatment strategies for iodine deficiency disorders in Germany

OBJECTIVE

More than 30% of the German population suffers from mild to moderate iodine deficiency causing goiter and other iodine deficiency disorders (IDDs). The economic burden of iodine deficiency is still unclear. We aimed to assess costs for prevention, monitoring and treatment of IDDs in Germany.

DESIGN

We performed a comprehensive cost analysis.

METHODS

We assessed direct medical costs and direct non-medical costs for inpatient and outpatient care of IDDs and costs for productivity loss due to the absence of work in 2018. Additionally, we calculated total costs for an IDD prevention program comprising universal salt iodization (USI). We performed threshold analyses projecting how many cases of IDDs or related treatments would need to be avoided for USI to be cost-saving.

RESULTS

Annual average costs per case in the year of diagnosis were € 211 for goiter/thyroid nodules; € 308 for hyperthyroidism; and € 274 for hypothyroidism. Average one-time costs for thyroidectomy were € 4184 and € 3118 for radioiodine therapy. Average costs for one case of spontaneous abortion were € 916. Annual costs of intellectual disability were € 14,202. In the German population, total annual costs for USI would amount to 8 million Euro. To be cost-saving, USI would need to prevent, for example, 37,900 cases of goiter/thyroid nodules.

CONCLUSION

USI potentially saves costs, if a minimum amount of IDDs per year could be avoided. In order to recommend the implementation of USI, a full health-economic evaluation including a comprehensive benefit-harm assessment is needed.

Vegans, Vegetarians and Pescatarians Are at Risk of Iodine Deficiency in Norway

Low iodine intakes have been documented in different population groups in Norway. We aimed to assess iodine status, dietary intake, supplement and macroalgae use, and iodine knowledge in vegans, vegetarians and pescatarians. In this study, 115 vegans, 55 vegetarians and 35 pescatarians from the Oslo region of Norway, aged 18-60 years, participated. A spot urine sample was collected along with a dietary assessment of iodine intake, supplement and macroalgae use. The median urinary iodine concentration (MUIC) in vegans was 43 µg/L (moderate iodine deficiency), in vegetarians 67 µg/L and in pescatarians 96 µg/L (mild iodine deficiency). In multiple linear regression analysis, use of iodine supplements was one of the strongest predictors of UIC. About half of the participants had median 24-h iodine intakes below estimated average requirement (EAR) of 100 µg/day. Fifty percent had low knowledge score, while 27% had very low knowledge score. Vegans, vegetarians and possibly pescatarians in Norway, are unable to reach the recommended iodine intake merely from food and are dependent on iodine supplements. There is an urgent need for dietary guidance targeting vegans, vegetarians and pescatarians to avoid inadequate iodine intake in non-supplement users, as well as avoiding excess iodine intake in macroalgae users.

Incidence of hypothyroidism after treatment for breast cancer-a Danish matched cohort study

Background

Breast cancer survivors (BCS) may have increased risk of hypothyroidism, but risk according to treatment modality is unclear. We estimated the incidence of hypothyroidism in women with breast cancer, and according to cancer treatment.

Methods

Using nationwide registries, we identified all Danish women aged ≥ 35 years diagnosed with non-metastatic breast cancer (1996–2009). We matched up to five cancer-free women (controls) for each BCS. We excluded women with prevalent thyroid disease. Cancer treatment was chemotherapy with or without radiotherapy (RT) targeting the breast/chest wall only, or also the lymph nodes (RTn). We identified hypothyroidism using diagnostic codes, and/or levothyroxine prescriptions. We calculated the cumulative incidence, incidence rates (IR) per 1000 person-years, and used Cox regression to estimate hazard ratios (HR) and associated 95% confidence intervals (CIs) of hypothyroidism, adjusting for comorbidities.

Results

We included 44,574 BCS and 203,306 matched controls with 2,631,488 person-years of follow-up. BCS had a slightly higher incidence of hypothyroidism than controls [5-year cumulative incidence, 1.8% (95%CI = 1.7–1.9) and 1.6% (95%CI = 1.5–1.6), respectively]. The overall IR was 4.45 (95%CI = 4.25–4.67) and 3.81 (95%CI = 3.73–3.90), corresponding to an adjusted HR = 1.17 (95%CI = 1.11–1.24). BCS who received RTn with chemotherapy (HR = 1.74, 95%CI = 1.50–2.02) or without chemotherapy (HR = 1.31, 95%CI = 1.14–1.51) had an elevated risk of hypothyroidism compared with matched controls and compared with BCS who underwent surgery alone [HR = 1.71, 95%CI = 1.45–2.01 and HR = 1.36, 95%CI = 1.17–1.58, respectively].

Conclusions

BCS have an excess risk of hypothyroidism compared with age-matched controls. BCS and those working in cancer survivorship settings ought to be aware that this risk is highest in women treated with radiation therapy to the lymph nodes and chemotherapy.

Thyroid function abnormalities and thyroid autoantibodies in Danish pregnant women

OBJECTIVE

Abnormal thyroid function in pregnant women is a matter of concern. Knowledge on the occurrence of known and unidentified thyroid function abnormalities in a large unselected cohort of pregnant women is warranted as part of the debate on benefits and risks of routine testing.

DESIGN

Cohort study.

PARTICIPANTS

A total of 14 323 pregnant women in the North Denmark Region, who had a blood sample drawn as part of the prenatal screening program in early pregnancy (2011-2015).

MEASUREMENTS

TSH, free thyroxine, thyroid peroxidase and thyroglobulin antibodies were measured in the stored blood samples using an automatic immunoassay (ADVIA Centaur XPT, Siemens Healthineers). Cohort-, method- and week-specific reference ranges were used for classification of maternal thyroid function, and a cut-off of 60 U/mL was used for thyroid autoantibodies. Information in Danish nationwide registers was used to identify diagnosed and treated maternal thyroid disease.

RESULTS

Overall, 15.2% had thyroid function abnormalities in the early pregnancy and 14.9% were thyroid peroxidase and/or thyroglobulin antibody positive. Among women with known thyroid disease (n = 365), the frequency of abnormal thyroid function was 45.7%, and 62.8% in women (n = 172) who received current treatment in the pregnancy. When maternal thyroid disease was diagnosed in the years following pregnancy (n = 313), 46.7% had abnormal thyroid function and 54.3% were thyroid peroxidase and/or thyroglobulin antibody positive in the early pregnancy.

CONCLUSION

Thyroid function abnormalities and thyroid autoantibodies were common in Danish pregnant women, particularly in women with known or later diagnosed thyroid disease, which raises concern about inadequately treated and unidentified abnormal thyroid function.

Electrocardiography in euthyroid individuals: a Danish general population study

BACKGROUND

Thyroid hormones within the euthyroid range have been linked to mortality and differences in heart rate. However, some relations between thyroid hormone concentration and various electrocardiographic measurements remain unassessed. We aimed to investigate the association between thyroid hormone concentrations within the euthyroid range and different electrocardiographic markers in people free of thyroid disease.

METHODS

We obtained electrocardiograms (ECG) and blood samples of free T4, total T3, and thyrotropin (TSH) in 20,852 subjects from the general population (the GESUS study). Relations between concentrations of TSH, free T4, and total T3 and heart rate, QTc, QRS duration, PR interval, P-wave duration and T-wave morphology were assessed in a multivariate adjusted linear model stratified by sex.

RESULTS

Roughly half of the 18,046 included participants with thyroid hormone measurements within euthyroid range were men, and the average age was 56 years. Heart rate increased with concentrations of T3 (6.4 bpm/nM, P<0.001 in women and 5.3 bpm/nM, P<0.001 in men) and T4 (3.7 bpm/10pM, P<0.001 in women and 3.1 bpm/10pM, P<0.001 in men). We found no relation between TSH and heart rate. PR interval and QRS duration decreased with higher concentrations of T3 (all P<0.01). QTc increased with higher concentrations of T4 in men (5 ms/10pM), and T waves were flatter, more asymmetric, and more often had notches with higher concentrations of T4 (all P≤0.01).

CONCLUSIONS

Thyroid hormone concentrations within the euthyroid range in people free of thyroid disease were associated with changes in the electrocardiogram in a general population.

Long-term iodine nutrition is associated with longevity in older adults: a 20 years’ follow-up of the Randers–Skagen study

Iodine intake affects the occurrence of thyroid disorders. However, the association of iodine intake with longevity remains to be described. This led us to perform a 20 years’ follow-up on participants from the Randers–Skagen (RaSk) study. Residents in Randers born in 1920 (n 210) and Skagen born in 1918–1923 (n 218) were included in a clinical study in 1997–1998. Mean iodine content in drinking water was 2 µg/l in Randers and 139 µg/l in Skagen. We collected baseline data through questionnaires, performed physical examinations and measured iodine concentrations in spot urine samples. Income data were retrieved from Danish registries. We performed follow-up on mortality until 31 December 2017 using Danish registries. Complete follow-up data were available on 428 out of 430 of participants (99·5 %). At baseline, the median urinary iodine concentration was 55 µg/l in Randers and 160 µg/l in Skagen residents. Participants were long-term residents with 72·8 and 92·7 % residing for more than 25 years in Randers and Skagen, respectively. Cox regression showed that living in Skagen compared with Randers was associated with a lower hazard ratio (HR) of death in both age- and sex-adjusted analyses (HR 0·60, 95 % CI 0·41, 0·87, P = 0·006), but also after adjustment for age, sex, number of drugs, Charlson co-morbidity index, smoking, alcohol and income (HR 0·60, 95 % CI 0·41, 0·87, P = 0·008). Residing in iodine-replete Skagen was associated with increased longevity. This indicates that long-term residency in an iodine-replete environment may be associated with increased longevity compared with residency in an iodine-deficient environment.

Immunometabolism: an overview and therapeutic prospects in autoimmune diseases

Metabolism is a critical immune regulator under physiologic and pathologic conditions. Culminating evidence has disentangled the contribution of distinct metabolic pathways, namely glucolysis, pentose phosphate, fatty acid oxidation, glutaminolysis, Krebs cycle and oxidative phosphorylation, in modulating innate and adaptive immune cells based on their activation/differentiation state. Metabolic aberrations and changes in the intracellular levels of specific metabolites are linked to the inflammatory phenotype of immune cells implicated in autoimmune disorders such as systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis and diabetes. Notably, targeting metabolism such as the mTOR by rapamycin, hexokinase by 2-deoxy-D-glucose, AMP-activated protein kinase by metformin, may be used to ameliorate autoimmune inflammation. Accordingly, research in immunometabolism is expected to offer novel opportunities for monitoring and treating immune-mediated diseases.

Thyroid function before and after Roux-en-Y gastric bypass: an observational study

BACKGROUND

Population studies have shown a positive association between thyroid-stimulating hormone (TSH) and body mass index. Recent studies have shown a significant increase in the prevalence of subclinical hypothyroidism (SCH) in obesity. Weight reduction after Roux-en-Y gastric bypass (RYGB) seems to significantly decrease TSH levels.

OBJECTIVES

The purpose of this study was to evaluate the prevalence of SCH in obese patients (class II and III) and to observe the behavior of thyroid hormones (TSH, hormone triiodothyronine, thyroxine, free thyroxine) with significant weight loss after RYGB.

SETTING

Hospital Nossa Senhora das Graças, Curitiba, Paraná, Brazil.

METHODS

We retrospectively reviewed the medical records of 215 obese patients who underwent RYGB between 2005 and 2012 with a follow-up of at least 2 years. The study was observational and descriptive. The selected times for clinical and laboratory evaluations were preoperative, 3, 6, 12, and 24 months after the procedure. Association, correlation, and variance analyses were performed.

RESULTS

The prevalence of SCH preoperatively was 9.3%. SCH was corrected in 89.5% of patients 12 months after RYGB. We did not find an association between TSH and BMI (r = .002, P = .971). There was a positive impact of bariatric surgery on all metabolic variables. We showed that serum TSH level had no positive correlation with the presence or absence of metabolic syndrome.

CONCLUSIONS

Weight loss after bariatric surgery leads to normalization of TSH levels in most patients and none developed overt hypothyroidism. Obese patients with SCH should not be treated with thyroid hormone replacement. Serial monitoring of thyroid function after obesity therapy seems to be a reasonable approach.

Changes in subtypes of overt thyrotoxicosis and hypothyroidism following iodine fortification

OBJECTIVE

To investigate the impact of mandatory iodine fortification (IF) on the incidence of nosological subtypes of overt thyrotoxicosis and hypothyroidism.

DESIGN

We identified and scrutinized all possible new cases of overt thyrotoxicosis and hypothyroidism in an open cohort in Northern Jutland (n = 309 434; 1 January 1997) during the years 2014-2016. Individual medical history was evaluated to verify and detail the incidence of overt thyroid dysfunction and for classification into nosological subtypes. A number of cases were excluded during final verification due to spontaneous normalization of thyroid function, as they had no medical history suggesting a known condition, which could transiently affect thyroid function (subacute/silent thyroiditis, PPTD and iatrogenic thyroid dysfunction). An identical survey was conducted in 1997-2000 prior to mandatory IF of salt (13 µg/g) that was in effect from year 2001.

RESULTS

The standardized incidence rate (SIR) of verified overt thyrotoxicosis decreased markedly from 97.5/100 000/year in 1997-2000 to 48.8 in 2014-2016 (SIRR: 0.50 [95% CI: 0.45-0.56]). This was due to a distinct decrease in the SIR of multinodular toxic goitre (SIRR: 0.18 [0.15-0.23]), solitary toxic adenoma (SIRR: 0.26 [0.16-0.43]) and to a lesser degree Graves' disease (SIRR: 0.67 [0.56-0.79]). SIR for overt hypothyroidism was unaltered by 2014-2016 (SIRR: 1.03 [0.87-1.22]). However, age distribution shifted with more young and fewer elderly cases of verified overt hypothyroidism.

CONCLUSION

Mandatory IF caused a substantial reduction in SIR of verified overt thyrotoxicosis (especially of nodular origin) while avoiding an increase in SIR of verified overt hypothyroidism.

Transient Hyperthyroidism following the ingestion of complementary medications containing kelp seaweed: A case-report

RATIONALE

The prevalence of obesity has increased over the past few years, becoming a public health problem. Generally, the primary therapeutic remedies are diet, physical exercise, medication, and bariatric surgery. However, an increased number of obese and overweight people are using complementary and herbal slimming supplements.

PATIENT CONCERNS

A 70-years-old Caucasian woman presented to the outpatient clinic with tachycardia (>100 bpm), insomnia, anxiety, and recent weight loss (6 kilos in 3 months). She had no previous thyroid disease, but she presented transient hyperthyroidism at 3 months after ingestion of tablets containing kelp seaweeds.

DIAGNOSES

Hypertensive and obese patient, without previous thyroid disease, presented with transient hyperthyroidism at 3 months following ingestion of tablets containing kelp seaweed.

INTERVENTIONS

The kelp-containing tablets were discontinued, and antithyroid therapy with Methimazole was initiated as follows: Methimazole at 15 mg/day for 1 month, at 10 mg/day in the second month, and 5 mg/day for the third month.

OUTCOMES

After 3 months of antithyroid therapy and without the consumption of kelp - containing tablets, normal thyroid function was regained. Further analysis revealed normal thyroid function, so the hyperthyroidism reversed completely.

LESSONS

Adults who consume complementary medication based on kelp seaweed should be informed of the risk of developing thyroid dysfunction also in the absence of any pre-existing thyroid disease. Due to the high iodine content, supplements containing kelp should be taken with the supervision of a physician and with monitoring of thyroid function.

Increased Incidence Rate of Hypothyroidism After Iodine Fortification in Denmark: A 20-Year Prospective Population-Based Study

OBJECTIVE

To monitor the impact of a cautious iodine fortification (IF) on the incidence of overt hypothyroidism in two subpopulations with different levels of preexisting iodine deficiency (ID).

DESIGN

A 20-year (1997 to 2016) prospective population-based study identified all new cases of diagnosed overt biochemical hypothyroidism in two open cohorts: a western cohort with moderate ID (n = 309,434; 1 January 1997) and an eastern cohort with mild ID (n = 224,535; 1 January 1997). A diagnostic algorithm was applied to all thyroid function tests performed within the study areas, and possible new cases were verified individually. Mandatory IF of salt was initiated in mid-2000 (13 ppm). The current study is a part of the DanThyr study.

RESULTS

At baseline, standardized incidence rates (SIRs) of hypothyroidism were 32.9 and 47.3/100.000/y in the cohorts with moderate and mild ID, respectively. The SIR of hypothyroidism increased significantly in both cohorts after implementing mandatory IF, with peak values of 150% in 2014 to 2016 for the moderate ID cohort and 130% in 2004 to 2005 for the mild ID cohort. Significant increases in SIR were seen among the young and middle-aged participants of both cohorts, whereas no changes were seen among the elderly participants (≥60 years). The follow-up period for the mildly iodine-deficient cohort was restricted up to and including 2008.

CONCLUSION

The cautious initiation of the IF program in Denmark caused a sustained increase in hypothyroidism incidence among subjects residing in areas of moderate and mild ID but only among the young and middle-aged participants.

Previous Live Births and Induced Abortions May Precede Later Development of Graves' Hyperthyroidism

OBJECTIVE

To investigate the association between reproductive history and later development of various nosological subtypes of overt hyperthyroidism.

STUDY DESIGN

From the Danish population, we included incident hyperthyroid women, and for each case we recruited 4 euthyroid age-sex-region-matched controls from the same sub-population. Hyperthyroid cases/controls were: Graves' disease (GD, n = 232/928), multinodular toxic goitre (MNTG, n = 91/364), solitary toxic adenoma (STA, n = 21/84). Patients diagnosed with hyperthyroidism within 1 year after delivery including post-partum GD were excluded. In multivariate conditional regression models (reference: no reproductive events), we analysed the association between development of GD/MNTG/STA and reproductive factors such as age at menarche/menopause, reproductive span, number of pregnancies/childbirths/abortions, investigations for infertility, and years on oral contraceptives. We adjusted for possible confounders such as alcohol intake, smoking, co-morbidity, and education. Age was studied as a potential effect measure modifier.

RESULTS

GD patients diagnosed before the age of 40 years had given births more often than control subjects (OR [95% CI] for 1/2/3+ births [ref.: nulliparous] were 1.57 [0.80-3.11]/2.06 [1.001-4.22]/3.07 [1.50-6.26]), and they had induced abortions performed more often (OR for 1/2+ induced abortions [ref.: no: events] were 0.99 [0.54-1.84]/2.24 [1.12-4.45]). No associations were observed between any reproductive factor and the development of MNTG or STA.

CONCLUSIONS

Childbirths and induced abortions may be followed by development of Graves' hyperthyroidism after the post-partum period. This was not the case for the non-autoimmune subtypes of hyperthyroidism.

Pregnancy Week-Specific Reference Ranges for Thyrotropin and Free Thyroxine in the North Denmark Region Pregnancy Cohort

BACKGROUND

Physiological changes in maternal thyroid function during pregnancy necessitate the use of pregnancy-specific reference ranges. Dynamic changes in thyrotropin (TSH) within the first trimester of pregnancy have been reported, but more evidence is needed to substantiate the findings. The objective of this study was to estimate pregnancy week-specific reference ranges for maternal TSH and free thyroxine (fT4) in early pregnancy.

METHODS

The study consecutively recruited serum residues from blood samples collected as part of the prenatal screening in the North Denmark Region, 2011-2015. TSH, fT4, thyroid peroxidase antibodies (TPOAb), and thyroglobulin antibodies (TgAb) were measured using an ADVIA Centaur XPT immunoassay. The reference cohort included 10,337 pregnant women who had no thyroid disease or other autoimmune diseases and were TPOAb- and TgAb negative. The main outcome measures were lower and upper reference limits (2.5th and 97.5th percentiles) for TSH and fT4 stratified by week of pregnancy.

RESULTS

Blood samples were drawn in pregnancy weeks 4-20 (median week 10), and 92% of the pregnancies ended with a live birth. TSH varied considerably in the first trimester of pregnancy, and the levels were highest in early pregnancy (weeks 4-6: 0.6-3.7 mIU/L) followed by a gradual decline to lower levels in weeks 9-11 (0.1-2.8 mIU/L) and 12-14 (0.03-2.8 mIU/L). Maternal fT4 showed less variation (weeks 4-6: 12-20 pmol/L; weeks 9-11: 13-21 pmol/L; weeks 12-14: 13-20 pmol/L).

CONCLUSIONS

The results corroborate dynamic week-specific changes in maternal TSH in early pregnancy. The use of uniform lower and upper reference limits for TSH in early pregnancy may be too simple.

Evolving Understanding of the Epidemiology of Thyroid Cancer

The incidence of thyroid cancer worldwide has increased significantly over the past 3 decades, due predominantly to an increase in papillary thyroid cancer. Although most of these cancers are small and localized, population-based studies have documented a significant increase in thyroid cancers of all sizes and stages, in addition to incidence-based mortality for papillary thyroid cancer. This suggests that the increasing incidence of thyroid cancer is due in large part to increasing surveillance and overdiagnosis, but that there also appears to be a true increase in new cases of thyroid cancer.

Validation of plasma thyroxine and triiodothyronine methods on the ADVIA Centaur® XP

Standardization programs for thyroid hormones have revealed bias between immunochemical methods and the reference method ED-ID-LC/MS. Lack of standardization between methods, suboptimal reference intervals and replacement of serum with plasma may compromise the capability of the immunochemical thyroid methods to diagnose thyroid disease. To accommodate the demand for faster turn-around times for laboratory replies, we replaced serum with plasma on some serum CE marked thyroid methods. This forced us to do on-board analytical correction for the plasma total T4 (TT4) method on ADVIA Centaur^® XP. We, next, validated the capability of the ADVIA Centaur^® XP thyroid methods on plasma by (1) first carrying out a prospective method comparison with the ED-ID-LC/MS reference method using collected plasma samples, (2) we verified the clinical reference intervals by analyzing collected plasma samples from healthy individuals, and (3) retrospectively compared laboratory results from two different time periods using serum TT4 and serum total triiodothyronine (TT3) versus plasma free thyroxine (FT4) and plasma TT3, respectively, to diagnose thyroid disease. The plasma FT4 method displayed a negative concentration-dependent bias against the reference method. This bias was apparently counteracted by a fitted reference interval for the plasma FT4 method. Indeed, overt hyperthyroid disease was found in 1.0% and 1.1% of the cases using serum and plasma and overt hypothyroid condition were in 1.3% and 0.6% of the cases using serum and plasma, respectively. In conclusion, the ADVIA Centaur^® XP FT4 method displayed a negative bias at high plasma FT4 concentrations against the reference method, but the diagnostic performance was not compromised due to a fitted reference interval.

Insulin-like Growth Factor-I Receptor and Thyroid-Associated Ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is a complex disease process presumed to emerge from autoimmunity occurring in the thyroid gland, most frequently in Graves disease (GD). It is disfiguring and potentially blinding, culminating in orbital tissue remodeling and disruption of function of structures adjacent to the eye. There are currently no medical therapies proven capable of altering the clinical outcome of TAO in randomized, placebo-controlled multicenter trials. The orbital fibroblast represents the central target for immune reactivity. Recent identification of fibroblasts that putatively originate in the bone marrow as monocyte progenitors provides a plausible explanation for why antigens, the expressions of which were once considered restricted to the thyroid, are detected in the TAO orbit. These cells, known as fibrocytes, express relatively high levels of functional TSH receptor (TSHR) through which they can be activated by TSH and the GD-specific pathogenic antibodies that underpin thyroid overactivity. Fibrocytes also express insulin-like growth factor I receptor (IGF-IR) with which TSHR forms a physical and functional signaling complex. Notably, inhibition of IGF-IR activity results in the attenuation of signaling initiated at either receptor. Some studies suggest that IGF-IR-activating antibodies are generated in GD, whereas others refute this concept. These observations served as the rationale for implementing a recently completed therapeutic trial of teprotumumab, a monoclonal inhibitory antibody targeting IGF-IR in TAO. Results of that trial in active, moderate to severe disease revealed dramatic and rapid reductions in disease activity and severity. The targeting of IGF-IR with specific biologic agents may represent a paradigm shift in the therapy of TAO.

Iodine Status After Bariatric Surgery-a Prospective 10-Year Report from the Swedish Obese Subjects (SOS) Study

CONTEXT

Bariatric surgery can lead to nutrient deficiencies. Gastric by-pass (GBP) entails restriction and malabsorption, whereas, vertical banded gastroplasty (VBG) is only restrictive.

OBJECTIVE

The objective of this study is to study whether GBP-patients develop iodine deficiency from malabsorption, and if GBP- and VBG-patients develop lower 24-h urinary iodine excretion (24-UIE) than obese non-operated controls (OB-controls) due to lower iodine intake.

DESIGN

The Swedish Obese Subjects (SOS) study is a prospective, non-randomized study of 4047 obese patients included 1987-2001, who chose bariatric surgery or non-surgical treatment. SOS-groups were compared at baseline, after 2 and 10 years and with population-based subsamples (MONICA-controls).

PATIENTS

One hundred eighty-eight GBP-patients were matched with 188 VBG-patients and 188 OB-controls and with three subgroups from 412 MONICA-controls.

MAIN OUTCOME MEASUREMENTS

Primary outcome was 24-UIE. Secondary outcomes were iodine intake, iodine supplementation, TSH, FT4, and thyroid morbidity.

RESULTS

At baseline, median 24-UIE was higher in GBP-patients, VBG-patients and OB-controls than in MONICA-controls (214, 201, 203 and 137 μg/day, p < 0.001). At 10 years, 24-UIE in GBP-patients (161 μg/day) and VBG-patients (149 μg/day) was lower compared with baseline (p < 0.01) and OB-controls (189 μg/day, p < 0.01), but similar to 24-UIE in MONICA-controls (137 μg/day). The 10-year-dietary iodine intake was similar in GPB-patients and OB-controls, but higher in VBG-patients. Iodine supplementation was taken by 0-9% in SOS-groups.

CONCLUSION

After surgery, GBP- and VBG-patients did not suffer from iodine deficiency, but both groups had lower iodine status than OB-controls. Dietary supplements recommended after bariatric surgery do not need to include iodine, in iodine sufficient countries.

TRIAL REGISTRATION

clinicaltrials.gov : NCT01479452.