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Journal of Thyroid Research
Volume 2012, Article ID 798963, 6 pages
http://dx.doi.org/10.1155/2012/798963
Research Article

Iodine Intake and Thyroid Function in Pregnant Women in a Private Clinical Practice in Northwestern Sydney before Mandatory Fortification of Bread with Iodised Salt

1Department of Obstetrics and Gynaecology, Blacktown Hospital and Norwest Private Hospital, 9 Norbrik Drive, Bella Vista 2153, Sydney, NSW, Australia
2NHMRC Clinical Trials Centre, Faculty of Medicine, 92 Parramatta Road, Camperdown, Sydney, NSW 2050, Australia
3International Council for Control of Iodine Deficiency Disorders, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
4Sydney Thyroid Clinic, Westmead Specialist Centre, Suite 8, 16-18 Mons Road Westmead, NSW 2145, Australia

Received 1 June 2012; Accepted 28 August 2012

Academic Editor: Elizabeth N. Pearce

Copyright © 2012 Norman Blumenthal et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Aim. The primary objective of the study was to assess the iodine nutritional status, and its effect on thyroid function, of pregnant women in a private obstetrical practice in Sydney. Methods. It was a cross-sectional study undertaken between November 2007 and March 2009. Blood samples were taken from 367 women at their first antenatal visit between 7 and 11 weeks gestation for measurement of thyroid stimulating hormone (TSH) and free thyroxine (FT4) levels and spot urine samples for urinary iodine excretion were taken at the same time as blood collection. Results. The median urinary iodine concentration (UIC) for all women was 81 μg/l (interquartile range 41–169 μg/l). 71.9% of the women exhibited a UIC of <150 μg/l. 26% of the women had a UIC <50 μg/l, and 12% had a UIC <20 μg/l. The only detectable influences on UIC were daily milk intake and pregnancy supplements. There was no statistically significant association between UIC and thyroid function and no evidence for an effect of iodine intake on thyroid function. Conclusions. There is a high prevalence of mild to moderate iodine deficiency in women in Western Sydney but no evidence for a significant adverse effect on thyroid function. The 6.5% prevalence of subclinical hypothyroidism is unlikely to be due to iodine deficiency.