Development of thyroid dysfunction among women with excessive iodine intake--A 3-year follow-up

Inger Aakre; Trine Bjøro; Ingrid Norheim; Tor A Strand; Ingrid Barikmo; Sigrun Henjum

doi:10.1016/j.jtemb.2015.03.004

Development of thyroid dysfunction among women with excessive iodine intake--A 3-year follow-up

J Trace Elem Med Biol. 2015:31:61-6. doi: 10.1016/j.jtemb.2015.03.004. Epub 2015 Mar 30.

Authors

Inger Aakre¹, Trine Bjøro², Ingrid Norheim³, Tor A Strand⁴, Ingrid Barikmo⁵, Sigrun Henjum⁵

Affiliations

¹ Department of Health Nutrition and Management, Faculty of Health Sciences, Oslo and Akershus University College, Oslo, Norway; Department of Global Public Health and Primary Care, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway. Electronic address: inger.aakre@hioa.no.
² Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
³ Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital, Oslo, Norway.
⁴ Department of Global Public Health and Primary Care, Faculty of Medicine and Dentistry, University of Bergen, Bergen, Norway; Medical Microbiology, Department of Laboratory Medicine, Medical Services Division, Innlandet Hospital Trust, Lillehammer, Norway.
⁵ Department of Health Nutrition and Management, Faculty of Health Sciences, Oslo and Akershus University College, Oslo, Norway.

PMID: 26004893
DOI: 10.1016/j.jtemb.2015.03.004

Abstract

Objectives: Thyroid dysfunction can be a result of excessive iodine intake, which may have adverse health consequences, particularly for women in fertile age. In 2010, we conducted a cross-sectional study among lactating women with excessive iodine intake in the Saharawi refugee camps in Algeria and found a high prevalence of thyroid dysfunction. Three years later, we conducted a follow-up study to monitor the iodine situation and explore whether thyroid dysfunction still was highly prevalent when the women no longer were post-partum. None of the women were treated for hyper- or hypothyroidism between baseline and follow-up.

Methods: In 2013, we were able to recapture 78 of the 111 women from the baseline. Thyroid hormones and antibodies were measured in serum and thyroid size was assessed by palpation. Urinary iodine concentration (UIC) and drinking water iodine concentration were measured.

Results: The overall prevalence of thyroid dysfunction and/or positive antibodies was 34.3% and was not significantly changed from baseline. Of the non-pregnant women we reexamined, 17 had hypo- or hyperthyroidism in 2010; among these, 12 women still had abnormal thyroid function at follow-up. In addition, we found 9 new cases with marginally abnormal thyroid function. Women with thyroid dysfunction and/or positive antibodies had significantly higher BMI and thyroglobulin than women with normal thyroid function. We also found that women with high breast milk iodine concentration (BMIC) at baseline had more thyroid dysfunction at follow-up than the women with lower BMIC at baseline.

Conclusions: At follow-up, the prevalence of thyroid dysfunction was still high and had not changed during the 3 years between studies and from a postpartum period. The women still had a high iodine intake indicated by high UIC. Breast milk iodine concentration from baseline predicted thyroid dysfunction at follow-up.

Keywords: Developing countries; Follow-up; Iodine excess; Thyroid dysfunction; Urinary iodine.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Algeria
Cross-Sectional Studies
Drinking Water / chemistry
Female
Follow-Up Studies
Humans
Hyperthyroidism / epidemiology
Hyperthyroidism / etiology
Hypothyroidism / epidemiology
Hypothyroidism / etiology
Iodine / administration & dosage*
Iodine / adverse effects
Iodine / urine
Thyroid Function Tests
Thyroid Gland / drug effects*
Thyroid Gland / physiopathology

Substances

Drinking Water
Iodine