4727.0.55.002 - Australian Aboriginal and Torres Strait Islander Health Survey: Users' Guide, 2012-13

ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 10/09/2014 First Issue

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Contents >> Biomedical Measures >> Iodine biomarker

IODINE

Definition

Iodine is a trace element that is essential for development and growth of the human body and is required to synthesise thyroid hormones. Having an adequate iodine intake is especially important for foetal development of the brain, which is one of the reasons women of child bearing age are advised to increase their iodine intake before conception, during pregnancy and whilst breastfeeding¹.

National Iodine Guidelines

Data on iodine levels has been collected in the National Aboriginal and Torres Strait Islander Health Measures Survey (NATSIHMS) and the National Health Measures Survey (NHMS) to provide national estimates and report on the effectiveness of the mandatory iodine fortification standard, developed by Food Standards Australia New Zealand (FSANZ).²

The iodine test measures the concentration of iodine in the urine that has been excreted from the body, at the time of the test (spot sample). Spot urine samples are not a sufficient measure for individual status, however these results can be used to assess the population iodine status.¹

Population

Iodine results were obtained for persons aged 18 years and over, who agreed to participate in the NATSIHMS and who provided a urine sample. Fasting was not required for this test.

Methodology

A urine sample was collected from participants and iodine levels were measured at the Sullivan Nicolaides Pathology (SNP) laboratory.

The World Health Organization (WHO) considers a population iodine deficient if the median urinary iodine concentration (UIC) is less than 100 μg/L. They also recommend that no more than 20% of the population have iodine concentrations below 50 μg/L.³

Further information about the analysis method and machines used to measure iodine levels is available in Excel spreadsheet format in the Downloads page of this product.

Data items

The data items and related output categories for this topic are available in Excel spreadsheet format from the Downloads tab of this product.

Interpretation

Points to be considered when interpreting data for this topic include the following:

Urinary iodine concentration from a single spot sample is not a sufficient measure to assess an individual's iodine status, however is considered appropriate when reporting at the population level.
There are a number of different test methods to measure iodine levels and each test method may produce different results.

Comparability with other surveys

The NATSIHMS is the first ABS Aboriginal and Torres Strait Islander survey to collect biomedical information. Given it was also the first national level survey (ABS or otherwise) to collect such data for the Aboriginal and Torres Strait Islander population, no comparisons with previous surveys for this population are possible.

However, biomedical data was also collected for all Australians in the 2011-12 National Health Measures Survey (NHMS) and information about comparisons between the NHMS results and those of non-ABS surveys is available from the Comparisons with other Australian surveys section of the Biomedical Results for Chronic Diseases, 2011-12 publication.

In the NATSIHMS, urinary iodine levels were measured using the inductively coupled plasma-mass spectrometry (ICP-MS) method. Many other studies such as the 2003–04 Australian National Iodine Nutrition Study (NINS)⁴ used the Sandell-Kolthoff spectrophotometric (S-K) method to measure iodine levels.

The World Health Organization and the International Council for Control of Iodine Deficiency Disorders (ICCIDD) determined a set of cut-offs using the S-K method to define if a population is iodine deficient.³ However, no agreed cut-offs have been developed yet for the new ICP-MS method. Therefore, the cut-offs for the S-K method were applied to the ICP-MS results in the NATSIHMS to determine iodine deficiency.

Research has shown there to be good agreement between the two methods overall, but the ICP-MS method may be more sensitive in detecting iodine deficiency than the S-K method.⁵ Therefore any comparison of iodine deficiency between the NATSIHMS and studies that used the S-K method should be applied with caution.

ENDNOTES

1 Gibson RS 2005, Principles of Nutritional Assessment, 2nd ed, New York: Oxford University Press.
2 Food Standards Australia New Zeland, 2012, Iodine fortification, <http://www.foodstandards.gov.au/consumer/nutrition/iodinefort/Pages/default.aspx>, Last accessed 08/09/2014.
3 WHO/UNICEF/ICCIDD 2007, Assessment of iodine deficiency disorders and monitoring their elimination: a guide for programme managers, 3rd ed. Geneva (Switzerland): World Health Organization, <http://whqlibdoc.who.int/publications/2007/9789241595827_eng.pdf>, Last accesssed 08/09/2014.
4 Li M, Eastman CJ, Waite KV, Ma G, Zacharin MR, Topliss DJ, Harding PE, Walsh JP, Ward LC, Mortimer RH, Mackenzie EJ, Byth K and Z Doyle 2006, Are Australian children iodine deficient? Results of the Australian National Iodine Nutrition Study, Medical Journal of Australia; 184(4): 165-169, <https://www.mja.com.au/journal/2006/184/4/are-australian-children-iodine-deficient-results-australian-national-iodine>, Last accessed 08/09/2014.
5 Li M, Ma G, Guttikonda K, Boyages SC, Waite K and CJ Eastman 2001, The re-emergence of iodine deficiency in Australia. Asia Pacific J Clin Nutr, 10:200-203.