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Iodine deficiency and thyroid disorders.

Abstract

Iodine deficiency early in life impairs cognition and growth, but iodine status is also a key determinant of thyroid disorders in adults. Severe iodine deficiency causes goitre and hypothyroidism because, despite an increase in thyroid activity to maximise iodine uptake and recycling in this setting, iodine concentrations are still too low to enable production of thyroid hormone. In mild-to-moderate iodine deficiency, increased thyroid activity can compensate for low iodine intake and maintain euthyroidism in most individuals, but at a price: chronic thyroid stimulation results in an increase in the prevalence of toxic nodular goitre and hyperthyroidism in populations. This high prevalence of nodular autonomy usually results in a further increase in the prevalence of hyperthyroidism if iodine intake is subsequently increased by salt iodisation. However, this increase is transient because iodine sufficiency normalises thyroid activity which, in the long term, reduces nodular autonomy. Increased iodine intake in an iodine-deficient population is associated with a small increase in the prevalence of subclinical hypothyroidism and thyroid autoimmunity; whether these increases are also transient is unclear. Variations in population iodine intake do not affect risk for Graves' disease or thyroid cancer, but correction of iodine deficiency might shift thyroid cancer subtypes toward less malignant forms. Thus, optimisation of population iodine intake is an important component of preventive health care to reduce the prevalence of thyroid disorders.

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  • Authors+Show Affiliations

    ,

    Human Nutrition Laboratory, Department of Health Sciences and Technology, Swiss Federal Institute of Technology (ETH) Zurich, Zurich, Switzerland. Electronic address: michael.zimmermann@hest.ethz.ch.

    Centre for Endocrinology, Diabetes & Metabolism, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK.

    Source

    MeSH

    Deficiency Diseases
    Food, Fortified
    Goiter
    Humans
    Hyperthyroidism
    Hypothyroidism
    Iodine
    Severity of Illness Index
    Thyroid Neoplasms

    Pub Type(s)

    Journal Article
    Review

    Language

    eng

    PubMed ID

    25591468

    Citation

    TY - JOUR T1 - Iodine deficiency and thyroid disorders. AU - Zimmermann,Michael B, AU - Boelaert,Kristien, Y1 - 2015/01/13/ PY - 2015/1/13/aheadofprint PY - 2015/1/17/entrez PY - 2015/1/17/pubmed PY - 2016/3/2/medline SP - 286 EP - 95 JF - The lancet. Diabetes & endocrinology JO - Lancet Diabetes Endocrinol VL - 3 IS - 4 N2 - Iodine deficiency early in life impairs cognition and growth, but iodine status is also a key determinant of thyroid disorders in adults. Severe iodine deficiency causes goitre and hypothyroidism because, despite an increase in thyroid activity to maximise iodine uptake and recycling in this setting, iodine concentrations are still too low to enable production of thyroid hormone. In mild-to-moderate iodine deficiency, increased thyroid activity can compensate for low iodine intake and maintain euthyroidism in most individuals, but at a price: chronic thyroid stimulation results in an increase in the prevalence of toxic nodular goitre and hyperthyroidism in populations. This high prevalence of nodular autonomy usually results in a further increase in the prevalence of hyperthyroidism if iodine intake is subsequently increased by salt iodisation. However, this increase is transient because iodine sufficiency normalises thyroid activity which, in the long term, reduces nodular autonomy. Increased iodine intake in an iodine-deficient population is associated with a small increase in the prevalence of subclinical hypothyroidism and thyroid autoimmunity; whether these increases are also transient is unclear. Variations in population iodine intake do not affect risk for Graves' disease or thyroid cancer, but correction of iodine deficiency might shift thyroid cancer subtypes toward less malignant forms. Thus, optimisation of population iodine intake is an important component of preventive health care to reduce the prevalence of thyroid disorders. SN - 2213-8595 UR - https://www.unboundmedicine.com/medline/citation/25591468/full_citation L2 - http://linkinghub.elsevier.com/retrieve/pii/S2213-8587(14)70225-6 ER -