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The influence of gestational stage on urinary iodine excretion in pregnancy


Stilwell, G and Reynolds, PJ and Parameswaran, V and Blizzard, C and Greenaway, TM and Burgess, JR, The influence of gestational stage on urinary iodine excretion in pregnancy, Journal of Endocrinology and Metabolism, 93, (5) pp. 1737-1742. ISSN 0021-972X (2008) [Refereed Article]


Copyright Statement

Copyright 2008 by The Endocrine Society

DOI: doi:10.1210/jc.2007-1715


Introduction: Median urinary iodine concentration (UIC) is the most commonly used indicator of population iodine nutrition. However, its validity as an indicator of dietary intake relies on a stable relationship between dietary iodine intake and urinary excretion. Physiological alterations in normal pregnancy, such as increased glomerular filtration rate, potentially invalidate UIC as an assessment tool in pregnancy.

Objective: The objective of the study was to document the impact of advancing gestation on UIC in normal pregnancy and determine whether the current reference intervals for general population iodine monitoring are appropriate for use in the context of pregnancy.

Design: Tasmania has a well-described history of mild iodine deficiency (school-age median UIC of 84 μg/liter). We assessed UIC in 759 urine samples from 431 women attending the Antenatal Clinic at the Royal Hobart Hospital, Tasmania's primary teaching hospital.

Main Outcome: The overall median UIC during pregnancy was 75 μg/liter (95% confidence interval 70.03-79.97 μg/liter) at a median gestation of 19.4 wk. Stratification by gestation, however, revealed a dynamic relationship between ioduria and gestation. Median UIC was elevated in early pregnancy and subsequently declined with advancing gestation.

Conclusion: In this mildly iodine-deficient population, current reference intervals for UIC overestimated the adequacy of iodine nutrition during the first and early second trimester of pregnancy. Gestation-specific UIC reference intervals are required to classify iodine nutrition during pregnancy. This is particularly important in populations with borderline iodine deficiency.

Item Details

Item Type:Refereed Article
Research Division:Health Sciences
Research Group:Epidemiology
Research Field:Epidemiology not elsewhere classified
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Stilwell, G (Dr Georgie Stilwell)
UTAS Author:Blizzard, C (Professor Leigh Blizzard)
UTAS Author:Greenaway, TM (Dr Tim Greenaway)
UTAS Author:Burgess, JR (Professor John Burgess)
ID Code:55775
Year Published:2008
Web of Science® Times Cited:54
Deposited By:Menzies Institute for Medical Research
Deposited On:2009-03-13
Last Modified:2015-02-05
Downloads:390 View Download Statistics

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