Iodine in drinking water varies by more than 100-fold in Denmark. Importance for iodine content of infant formulas

Pedersen, K. M.; Laurberg, Peter; Nøhr, Susanne Backman; Jørgensen, Arne Lund; Andersen, Stig

doi:10.1530/eje.0.1400400

Cited by 90 publications

(105 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the degree of baseline ID was the dominating predictor of a change in serum Tg even though the baseline differences in UIC between Aalborg and Copenhagen were small (53 mg/l vs 68 mg/l, and in participants not taking iodine supplements: 45 mg/l vs 61 mg/l). The difference in UIC is caused by differences in groundwater iodine content being around 5 mg/l in Aalborg and 20 mg/l in Copenhagen (32).…”

Section: European Journal Of Endocrinologymentioning

confidence: 99%

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

Krejbjerg

Bjergved

Pedersen

et al. 2015

European Journal of Endocrinology

View full text Add to dashboard Cite

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. Methods: We examined 2465 adults and a total of 1417 participants with no previous thyroid disease and without Tg-autoantibodies were included in the analyses. Serum Tg was measured by immunoradiometric method. We registered participants with a daily intake of iodine from supplements in addition to IF. Results: Overall, the follow-up period saw no change in median Tg in Copenhagen (9.1/9.1 mg/l, PZ0.67) while Tg decreased significantly in Aalborg (11.4/9.0 mg/l, P!0.001). Regional differences were evident before IF (Copenhagen/Aalborg, 9.1/11.4 mg/l, P!0.001), whereas no differences existed after IF (9.1/9.0 mg/l, PZ1.00). Living in Aalborg (P!0.001) and not using iodine supplements at baseline (PZ0.001) predicted a decrease in Tg whereas baseline thyroid enlargement (PZ0.02) and multinodularity (PZ0.01) were associated with an individual increase in Tg during follow-up. Conclusions: After IF we observed a decrease in median Tg in Aalborg and the previously observed regional differences between Aalborg and Copenhagen had levelled out. Likewise, living in Aalborg was a strong predictor of an individual decrease in serum Tg. Thus, even small differences in iodine intake at baseline were very important for the individual response to IF.

show abstract

Section: European Journal Of Endocrinologymentioning

confidence: 99%

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

Krejbjerg

Bjergved

Pedersen

et al. 2015

European Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…The small difference in iodine intake, mostly caused by differences in ground water iodine content (49), had a large impact on the incidence of subtypes of hyperthyroidism. While the incidence of GD was similar, MNTG was 87% more frequent in the most iodine-deficient region.…”

Section: Regional Difference In Incidence Of Hyperthyroidismmentioning

confidence: 99%

Epidemiology of subtypes of hyperthyroidism in Denmark: a population-based study

Carlé

Pedersen

Knudsen

et al. 2011

European Journal of Endocrinology

176

125

View full text Add to dashboard Cite

Objective: Few population-based studies have described the epidemiology of subtypes of hyperthyroidism. Design: A prospective population-based study, monitoring two well-defined Danish cohorts in Aalborg with moderate iodine deficiency (nZ311 102) and Copenhagen with only mild iodine deficiency (nZ227 632). Methods: A laboratory monitoring system identified subjects with thyroid function tests suggesting overt hyperthyroidism (low s-TSH combined with high s-thyroxine or s-triiodothyronine). For all subjects, we collected information on medical history, thyroid scintigraphy and thyroid hormone receptor antibody (TRAb) measurement. Information was used to disprove or verify primary overt hyperthyroidism and to subclassify hyperthyroidism into nosological disorders. Results: From 1997 to 2000 (2 027 208 person-years of observation), we verified 1682 new cases of overt hyperthyroidism. The overall standardized incidence rate (SIR) per 100 000 person-years was 81.6, and was higher in Aalborg compared with Copenhagen (96.7 vs 60.0, P!0.001), giving an SIR ratio (SIRR (95% confidence interval (CI))) between moderate versus mild iodine-deficient areas of 1.6 (1.4-1.8). Nosological types of hyperthyroidism (percentage/SIRR (95% CI)): multinodular toxic goitre (MNTG) 44.1%/1.9 (1.6-2.2), Graves' disease (GD) 37.6%/1.2 (0.99-1.4), solitary toxic adenoma (STA) 5.7%/2.4 (1.3-3.5), 'mixed type' hyperthyroidism (TRAb-positive, scintigraphicly multinodular) 5.4%/6.0 (3.0-12), subacute thyroiditis 2.3%/0.9 (0.4-1.4), postpartum thyroid dysfunction 2.2%/1.6 (0.8-3.0), amiodarone-associated hyperthyroidism 0.8%/7.1 (1.1-65), hyperthyroidism after thyroid radiation 0.7%/12.3 (0.8-50), lithium-associated hyperthyroidism 0.7%/0.97 (0.4-4.8) and hyperthyroidism caused by various other factors 0.7%. Lifetime risk for overt hyperthyroidism was 10.5%/6.5%/2.4% (females/all/males). Conclusion: Hyperthyroidism was common in Denmark with MNTG and GD as dominating entities. The higher incidence of hyperthyroidism in the most iodine-deficient region was caused by higher frequency of MNTG, 'mixed-type', STA and amiodarone-associated hyperthyroidism.

show abstract

“…2). The two geographical regions cover the main difference in levels of iodine intake in Denmark caused by different levels of iodine in ground water (7). Details on the random selection of cohorts from the population, participation rates, and analysis of potential bias caused by non-participation have been published (8).…”

Section: The Monitoring Programmentioning

confidence: 99%

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

et al. 2006

View full text Add to dashboard Cite

Objective: Denmark was an area of iodine deficiency, and mandatory iodine fortification of table salt and salt in bread (13 p.p.m. iodine) was initiated in 2000/2001. The Danish investigation on iodine intake and thyroid disease (DanThyr) is the monitoring of the iodine fortification program. Design and methods: DanThyr consists of three main parts: a study of population cohorts initialized before (nZ4649) and after (nZ3570) iodization of salt, a prospective identification of incident cases of overt hyper-and hypothyroidism in a population of around 550 000 people since 1997, and compilation of data from the national registers on the use of thyroid medication, thyroid surgery, and radioiodine therapy. Studies were carried-out in parallel in subcohorts living in areas with differences in iodine content of ground water. Results: The study showed profound effects of even small differences in iodine intake level on the prevalence of goiter, nodules, and thyroid dysfunction. Mild and moderate iodine deficiency was associated with a decrease in serum TSH with age. Other environmental factors were also important for goiter development (increase in risk, smoking and pregnancy; decrease in risk, oral contraception and alcohol consumption), and the individual risk depended on the genetic background. Environmental factors had only a minor influence on the prevalence of thyroid autoantibodies in the population. There were more cases of overt hypothyroidism in mild than in moderate iodine deficiency caused by a 53% higher incidence of spontaneous (presumably autoimmune) hypothyroidism. On the other hand, there were 49% more cases of overt hyperthyroidism in the area with moderate iodine deficiency. The cautious iodine fortification program, aiming at an average increase in iodine intake of 50 mg/day has been associated with a 50% increase in incidence of hyperthyroidism in the area with the most severe iodine deficiency. The incidence is expected to decrease in the future, but there may be more cases of Graves' hyperthyroidism in young people. Conclusion: A number of environmental factors influence the epidemiology of thyroid disorders, and even relatively small abnormalities and differences in the level of iodine intake of a population have profound effects on the occurrence of thyroid abnormalities. Monitoring and adjustment of iodine intake in the population is an important part of preventive medicine.European Journal of Endocrinology 155 219-228

show abstract

Iodine in drinking water varies by more than 100-fold in Denmark. Importance for iodine content of infant formulas

Cited by 90 publications

References 9 publications

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

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

Epidemiology of subtypes of hyperthyroidism in Denmark: a population-based study

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

Contact Info

Product

Resources

About