The Danish investigation on iodine intake and thyroid disease (DanThyr): history and implications.

Due to mild-to-moderate iodine deficiency in Denmark, health authorities initiated a voluntary iodine fortification (IF) program in 1998, which became mandatory in 2000. In line with recommendations from the World Health Organization, the Danish investigation on iodine intake and thyroid disease (DanThyr) was established to monitor the effect on thyroid health and disease. The program involved different study designs and followed two Danish sub-populations in the years before IF and up till 20 years after.

Improving Health and Diabetes Self-Management in Immigrants with Type 2 Diabetes Through a Co-Created Diabetes Self-Management Education and Support Intervention.

To examine the impact of a co-created culturally sensitive diabetes self-management education and support (DSMES) intervention on the physical and mental health of immigrants with type 2 diabetes (T2D). Pre- and post-test among people with T2D whose primary language was Urdu, Arabic or Turkish (n = 97). Participants were offered a six-week intervention based on a person-centred approach using research-based dialogue tools to facilitate learning and reflection, which was developed in co-creation with immigrants and healthcare professionals.

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).

Improving empowerment, motivation, and medical adherence in patients with poorly controlled type 2 diabetes: A randomized controlled trial of a patient-centered intervention.

Objective: To test whether an intervention consisting of four patient-centered consultations improves glycemic control and self-management skills in patients with poorly regulated type 2 diabetes (T2DM), compared to a control group receiving usual care.

Methods: Unblinded parallel randomized controlled trial including 97 adults diagnosed with T2DM ≥ 1 year and hemoglobin A1c (HbA1c) levels ≥ 8.0% (64 mmol/mol).

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.

Thyrotoxicosis after iodine fortification. A 21-year Danish population-based study.

Objective: Monitoring the influence of cautious iodine fortification (IF) on the incidence rate of overt thyrotoxicosis in Denmark with formerly frequent multinodular toxic goitre.

Design: A 21-year (1997-2017) prospective population-based study identified all new cases of overt biochemical thyrotoxicosis in two open cohorts: a Western cohort with moderate iodine deficiency (ID) and an Eastern cohort with mild ID (total n = 533 969 by 1 January 1997). A diagnostic algorithm was applied to all thyroid function tests performed within the study areas.

Iodine deficiency in pregnancy is prevalent in vulnerable groups in Denmark.

Introduction: Iodine is essential for the production of thyroid hormones. In pregnancy, physiological changes occur that can lead to iodine deficiency and impairment of fetal neurological development. We aimed to assess the iodine intake in pregnant women in Eastern Denmark, compare iodine levels in Eastern and Western Denmark and to identify potentially vulnerable groups.

Iodine status in the Nordic countries - past and present.

Background: Adequate iodine nutrition is dependent on ground water content, seafood, and, as many countries use iodized cow fodder, dairy products. In most countries, salt fortification programs are needed to assure adequate iodine intake.

Objectives: The objectives are threefold: 1) to describe the past and present iodine situation in the Nordic countries, 2) to identify important gaps of knowledge, and 3) to highlight differences among the Nordic countries' iodine biomonitoring and fortification policies.

Iodine excretion in school children in Copenhagen.

Introduction: Studies of dietary habits show a high iodine intake in children in Denmark. Iodine excretion in children has not previously been assessed. Iodine excretion in adults is below the recommended threshold, and it is therefore being discussed to increase the fortification level.

Parity and 11-Year Serum Thyrotropin and Thyroid Autoantibody Change: A Longitudinal Population-Based Study.

Background: A role for female reproductive factors in the pathogenesis of thyroid autoimmunity has been suggested. This study investigated the prospective association between parity, abortion, use of oral contraceptive pill (OCP), and use of hormone replacement therapy (HRT), and 11-year change in serum thyrotropin (TSH), as well as change in thyroid peroxidase autoantibody (TPOAb) status.

Methods: A random sample of 4649 people aged 18-65 years participated in a population-based study in the period 1997-1998.

Serum thyroglobulin before and after iodization of salt: an 11-year DanThyr follow-up study.

Objective: Our objective was to investigate individual serum thyroglobulin (Tg) changes in relation to iodine fortification (IF) and to clarify possible predictors of these changes.

Design: We performed a longitudinal population-based study (DanThyr) in two regions with different iodine intake at baseline: Aalborg (moderate iodine deficiency (ID)) and Copenhagen (mild ID). Participants were examined at baseline (1997) before the mandatory IF of salt (2000) and again at follow-up (2008) after IF.

Common variants in CYP2R1 and GC genes are both determinants of serum 25-hydroxyvitamin D concentrations after UVB irradiation and after consumption of vitamin D₃-fortified bread and milk during winter in Denmark.

Background: Little is known about how the genetic variation in vitamin D modulating genes influences ultraviolet (UV)B-induced 25-hydroxyvitamin D [25(OH)D] concentrations. In the Food with vitamin D (VitmaD) study, we showed that common genetic variants rs10741657 and rs10766197 in 25-hydroxylase (CYP2R1) and rs842999 and rs4588 in vitamin D binding protein (GC) predict 25(OH)D concentrations at late summer and after 6-mo consumption of cholecalciferol (vitamin D₃)-fortified bread and milk.

Objectives: In the current study, called the Vitamin D in genes (VitDgen) study, we analyzed associations between the increase in 25(OH)D concentrations after a given dose of artificial UVB irradiation and 25 single nucleotide polymorphisms located in or near genes involved in vitamin D synthesis, transport, activation, or degradation as previously described for the VitmaD study.

Iodine excretion has decreased in Denmark between 2004 and 2010--the importance of iodine content in milk.

Fortification with the essential trace element iodine is widespread worldwide. In the present study, results on iodine excretion and intake of iodine-rich foods from a cross-sectional study carried out in 2004-5, 4 to 5 years after the implementation of mandatory iodine fortification, were compared with data in a study carried out in 2008-10. The 2008-10 study was a follow-up of a cross-sectional study carried out before iodine fortification was implemented.

Thyroid nodules in an 11-year DanThyr follow-up study.

Context: Limited longitudinal data are available on changes in the thyroid gland structure in a population and how this is influenced by iodine fortification (IF).

Objective: Our objective was to clarify how IF influenced thyroid gland structure in 2 regions with different iodine intake at baseline (Copenhagen, mild iodine deficiency [ID]; Aalborg, moderate ID).

Design And Setting: We conducted a longitudinal population-based study (DanThyr) where participants were examined before (1997) and after (2008) the Danish mandatory IF of salt (2000).

Real-life use of vitamin D3-fortified bread and milk during a winter season: the effects of CYP2R1 and GC genes on 25-hydroxyvitamin D concentrations in Danish families, the VitmaD study.

Common genetic variants rs10741657 and rs10766197 in CYP2R1 and rs4588 and rs842999 in GC and a combined genetic risk score (GRS) of these four variants influence late summer 25-hydroxyvitamin D (25(OH)D) concentrations. The objectives were to identify those who are most at risk of developing low vitamin D status during winter and to assess whether vitamin D3-fortified bread and milk will increase 25(OH)D concentrations in those with genetically determined low 25(OH)D concentrations at late summer. We used data from the VitmaD study.

Vitamin D status and its determinants in children and adults among families in late summer in Denmark.

The impact of the familial relationship on vitamin D status has not been investigated previously. The objective of the present cross-sectional study was to assess serum 25-hydroxyvitamin D (25(OH)D) concentration and its determinants in children and adults among families in late summer in Denmark (56°N). Data obtained from 755 apparently healthy children (4-17 years) and adults (18-60 years) recruited as families (n 200) in the VitmaD study were analysed.

Thyroid function and body weight: a community-based longitudinal study.

Objective: Body weight and overt thyroid dysfunction are associated. Cross-sectional population-based studies have repeatedly found that thyroid hormone levels, even within the normal reference range, might be associated with body weight. However, for longitudinal data, the association is less clear.

Development of autoimmune overt hypothyroidism is highly associated with live births and induced abortions but only in premenopausal women.

Context: The 1-year postpartum period is often accompanied by increased risk for thyroid disease.

Objective: The objective of the study was to investigate the role of reproductive risk factors in the development of autoimmune overt hypothyroidism in the years after the 1-year postpartum period.

Design, Setting, And Subjects: In a population study, we included Danish women with new autoimmune overt hypothyroidism not diagnosed within the first year after a pregnancy (n = 117; median age 53.

Common variants in CYP2R1 and GC genes predict vitamin D concentrations in healthy Danish children and adults.

Environmental factors such as diet, intake of vitamin D supplements and exposure to sunlight are known to influence serum vitamin D concentrations. Genetic epidemiology of vitamin D is in its infancy and a better understanding on how genetic variation influences vitamin D concentration is needed. We aimed to analyse previously reported vitamin D-related polymorphisms in relation to serum 25(OH)D concentrations in 201 healthy Danish families with dependent children in late summer in Denmark.

Iodine fortification may influence the age-related change in thyroid volume: a longitudinal population-based study (DanThyr).

Objective: To assess the individuals' thyroid volume changes after the mandatory nationwide iodine fortification (IF) program in two Danish areas with different iodine intake at baseline (Copenhagen, mild iodine deficiency (ID) and Aalborg, moderate ID).

Design: A longitudinal population-based study (DanThyr).

Methods: We examined 2465 adults before (1997) and after (2008) the Danish IF of salt (2000).

Mandatory iodine fortification of bread and salt increases iodine excretion in adults in Denmark - a 11-year follow-up study.

Background & Aims: Iodine fortification is widespread. Systematic monitoring of iodine fortification programs should be carried out to secure an optimal fortification level. Our aim was to investigate the effectiveness of the Danish iodine fortification program by comparing iodine excretion at baseline and at 11-year follow-up, and to study determinants for any change in iodine intake including dietary habits, education, life style factors and health parameters.

Determinants of serum T4 and T3 at the time of diagnosis in nosological types of thyrotoxicosis: a population-based study.

Objective: To characterize thyroid hormone levels at the time of diagnosis in the nosological types of thyrotoxicosis diagnosed in the population and to analyze determinants for serum thyroxine (T4) and tri-iodothyronine (T3).

Design: Population-based study of thyrotoxicosis at disease onset.

Methods: In the period 1997-2000, we prospectively identified all patients diagnosed with incident primary overt thyrotoxicosis in a Danish population cohort and classified patients into ten well-defined nosological types of disease (n=1082).

Randomized controlled trial of the effects of vitamin D–fortified milk and bread on serum 25-hydroxyvitamin D concentrations in families in Denmark during winter: the VitmaD study.

Background: Vitamin D intakes are lower than dietary recommendations in most populations, and thus, a low vitamin D status is widespread, especially during winter.

Objective: We investigated the effects of increasing vitamin D intake to the recommended amount by fortification of milk and bread on serum 25-hydroxyvitamin D [25(OH)D] concentrations in families during winter in Denmark.

Design: The study was a randomized controlled trial in 782 children and adults (4-60 y old) recruited as 201 families.

The influence of early exposure to vitamin D for development of diseases later in life.

Background: Vitamin D deficiency is common among otherwise healthy pregnant women and may have consequences for them as well as the early development and long-term health of their children. However, the importance of maternal vitamin D status on offspring health later in life has not been widely studied. The present study includes an in-depth examination of the influence of exposure to vitamin D early in life for development of fractures of the wrist, arm and clavicle; obesity, and type 1 diabetes (T1D) during child- and adulthood.