Lower prevalence of mild hyperthyroidism related to a higher iodine intake in the population: prospective study of a mandatory iodization programme

Pernille Vejbjerg; Nils Knudsen; Hans Perrild; Peter Laurberg; Allan Carlé; Inge Bülow Pedersen; Lone B Rasmussen; Lars Ovesen; Torben Jørgensen

doi:10.1111/j.1365-2265.2008.03493.x

Lower prevalence of mild hyperthyroidism related to a higher iodine intake in the population: prospective study of a mandatory iodization programme

Pernille Vejbjerg, Nils Knudsen, Hans Perrild, Peter Laurberg, Allan Carlé, Inge Bülow Pedersen, Lone B Rasmussen, Lars Ovesen, Torben Jørgensen

43 Citations (Scopus)

Abstract

OBJECTIVE: Marked differences in pattern of thyroid dysfunction are seen in populations with different iodine intakes. We evaluated the influence of a higher iodine intake on thyroid hormone levels and the prevalence of thyroid dysfunction in the Danish population. DESIGN: Two cross-sectional studies matched on a group level according to sex and age. PARTICIPANTS: In all, 8219 individuals were examined before (n = 4649) or after (n = 3570) the introduction of a mandatory iodization programme in 2000 in two regions with established mild and moderate iodine deficiency. Serum TSH, fT(4) and fT(3 )were measured. An ultrasonography of the thyroid was performed. RESULTS: We found a higher median serum TSH after the introduction of mandatory iodization of salt: 1.51 mU/l (10-90th percentiles: 0.72-3.00) vs. 1.30 mU/l (10-90th percentiles: 0.59-2.66) before iodization. The difference was found in both regions and across age groups. There was a lower prevalence of mild hyperthyroidism and a tendency towards a lower prevalence of overt hyperthyroidism. The prevalence of mild hypothyroidism increased, most pronounced among young women after iodization. Conversely, there was a lower prevalence of undiagnosed overt hypothyroidism. However, when currently treated participants were included, the prevalence of hypothyroidism increased after iodization in the area with formerly mild iodine deficiency. CONCLUSION: A change in pattern of thyroid dysfunction was seen in relation to mandatory iodization of salt. There was no rise in the prevalence of hyperthyroidism and the prevalence of mild hyperthyroidism was halved. Conversely, prevalence of hypothyroidism increased.

Original language	English
Journal	Clinical Endocrinology
Volume	71
Issue number	3
Pages (from-to)	440-5
Number of pages	5
ISSN	0300-0664
DOIs	https://doi.org/10.1111/j.1365-2265.2008.03493.x
Publication status	Published - 2009

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Vejbjerg, P., Knudsen, N., Perrild, H., Laurberg, P., Carlé, A., Pedersen, I. B., Rasmussen, L. B., Ovesen, L., & Jørgensen, T. (2009). Lower prevalence of mild hyperthyroidism related to a higher iodine intake in the population: prospective study of a mandatory iodization programme. Clinical Endocrinology, 71(3), 440-5. https://doi.org/10.1111/j.1365-2265.2008.03493.x

Vejbjerg, P, Knudsen, N , Perrild, H, Laurberg, P, Carlé, A, Pedersen, IB, Rasmussen, LB, Ovesen, L & Jørgensen, T 2009, 'Lower prevalence of mild hyperthyroidism related to a higher iodine intake in the population: prospective study of a mandatory iodization programme', Clinical Endocrinology, vol. 71, no. 3, pp. 440-5. https://doi.org/10.1111/j.1365-2265.2008.03493.x

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title = "Lower prevalence of mild hyperthyroidism related to a higher iodine intake in the population: prospective study of a mandatory iodization programme",

abstract = "OBJECTIVE: Marked differences in pattern of thyroid dysfunction are seen in populations with different iodine intakes. We evaluated the influence of a higher iodine intake on thyroid hormone levels and the prevalence of thyroid dysfunction in the Danish population. DESIGN: Two cross-sectional studies matched on a group level according to sex and age. PARTICIPANTS: In all, 8219 individuals were examined before (n = 4649) or after (n = 3570) the introduction of a mandatory iodization programme in 2000 in two regions with established mild and moderate iodine deficiency. Serum TSH, fT(4) and fT(3 )were measured. An ultrasonography of the thyroid was performed. RESULTS: We found a higher median serum TSH after the introduction of mandatory iodization of salt: 1.51 mU/l (10-90th percentiles: 0.72-3.00) vs. 1.30 mU/l (10-90th percentiles: 0.59-2.66) before iodization. The difference was found in both regions and across age groups. There was a lower prevalence of mild hyperthyroidism and a tendency towards a lower prevalence of overt hyperthyroidism. The prevalence of mild hypothyroidism increased, most pronounced among young women after iodization. Conversely, there was a lower prevalence of undiagnosed overt hypothyroidism. However, when currently treated participants were included, the prevalence of hypothyroidism increased after iodization in the area with formerly mild iodine deficiency. CONCLUSION: A change in pattern of thyroid dysfunction was seen in relation to mandatory iodization of salt. There was no rise in the prevalence of hyperthyroidism and the prevalence of mild hyperthyroidism was halved. Conversely, prevalence of hypothyroidism increased.",

author = "Pernille Vejbjerg and Nils Knudsen and Hans Perrild and Peter Laurberg and Allan Carl{\'e} and Pedersen, {Inge B{\"u}low} and Rasmussen, {Lone B} and Lars Ovesen and Torben J{\o}rgensen",

note = "Keywords: Adolescent; Adult; Aged; Denmark; Female; Humans; Hyperthyroidism; Iodine; Male; Mandatory Programs; Middle Aged; Prevalence; Preventive Health Services; Program Evaluation; Prospective Studies; Sodium Chloride, Dietary; Thyroid Hormones; Young Adult",

year = "2009",

doi = "10.1111/j.1365-2265.2008.03493.x",

language = "English",

volume = "71",

pages = "440--5",

journal = "Clinical Endocrinology",

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TY - JOUR

T1 - Lower prevalence of mild hyperthyroidism related to a higher iodine intake in the population: prospective study of a mandatory iodization programme

AU - Vejbjerg, Pernille

AU - Knudsen, Nils

AU - Perrild, Hans

AU - Laurberg, Peter

AU - Carlé, Allan

AU - Pedersen, Inge Bülow

AU - Rasmussen, Lone B

AU - Ovesen, Lars

AU - Jørgensen, Torben

N1 - Keywords: Adolescent; Adult; Aged; Denmark; Female; Humans; Hyperthyroidism; Iodine; Male; Mandatory Programs; Middle Aged; Prevalence; Preventive Health Services; Program Evaluation; Prospective Studies; Sodium Chloride, Dietary; Thyroid Hormones; Young Adult

PY - 2009

Y1 - 2009

N2 - OBJECTIVE: Marked differences in pattern of thyroid dysfunction are seen in populations with different iodine intakes. We evaluated the influence of a higher iodine intake on thyroid hormone levels and the prevalence of thyroid dysfunction in the Danish population. DESIGN: Two cross-sectional studies matched on a group level according to sex and age. PARTICIPANTS: In all, 8219 individuals were examined before (n = 4649) or after (n = 3570) the introduction of a mandatory iodization programme in 2000 in two regions with established mild and moderate iodine deficiency. Serum TSH, fT(4) and fT(3 )were measured. An ultrasonography of the thyroid was performed. RESULTS: We found a higher median serum TSH after the introduction of mandatory iodization of salt: 1.51 mU/l (10-90th percentiles: 0.72-3.00) vs. 1.30 mU/l (10-90th percentiles: 0.59-2.66) before iodization. The difference was found in both regions and across age groups. There was a lower prevalence of mild hyperthyroidism and a tendency towards a lower prevalence of overt hyperthyroidism. The prevalence of mild hypothyroidism increased, most pronounced among young women after iodization. Conversely, there was a lower prevalence of undiagnosed overt hypothyroidism. However, when currently treated participants were included, the prevalence of hypothyroidism increased after iodization in the area with formerly mild iodine deficiency. CONCLUSION: A change in pattern of thyroid dysfunction was seen in relation to mandatory iodization of salt. There was no rise in the prevalence of hyperthyroidism and the prevalence of mild hyperthyroidism was halved. Conversely, prevalence of hypothyroidism increased.

AB - OBJECTIVE: Marked differences in pattern of thyroid dysfunction are seen in populations with different iodine intakes. We evaluated the influence of a higher iodine intake on thyroid hormone levels and the prevalence of thyroid dysfunction in the Danish population. DESIGN: Two cross-sectional studies matched on a group level according to sex and age. PARTICIPANTS: In all, 8219 individuals were examined before (n = 4649) or after (n = 3570) the introduction of a mandatory iodization programme in 2000 in two regions with established mild and moderate iodine deficiency. Serum TSH, fT(4) and fT(3 )were measured. An ultrasonography of the thyroid was performed. RESULTS: We found a higher median serum TSH after the introduction of mandatory iodization of salt: 1.51 mU/l (10-90th percentiles: 0.72-3.00) vs. 1.30 mU/l (10-90th percentiles: 0.59-2.66) before iodization. The difference was found in both regions and across age groups. There was a lower prevalence of mild hyperthyroidism and a tendency towards a lower prevalence of overt hyperthyroidism. The prevalence of mild hypothyroidism increased, most pronounced among young women after iodization. Conversely, there was a lower prevalence of undiagnosed overt hypothyroidism. However, when currently treated participants were included, the prevalence of hypothyroidism increased after iodization in the area with formerly mild iodine deficiency. CONCLUSION: A change in pattern of thyroid dysfunction was seen in relation to mandatory iodization of salt. There was no rise in the prevalence of hyperthyroidism and the prevalence of mild hyperthyroidism was halved. Conversely, prevalence of hypothyroidism increased.

U2 - 10.1111/j.1365-2265.2008.03493.x

DO - 10.1111/j.1365-2265.2008.03493.x

M3 - Journal article

C2 - 19067717

SN - 0300-0664

VL - 71

SP - 440

EP - 445

JO - Clinical Endocrinology

JF - Clinical Endocrinology

IS - 3

ER -

Lower prevalence of mild hyperthyroidism related to a higher iodine intake in the population: prospective study of a mandatory iodization programme

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