4363.0.55.001 - Australian Health Survey: Users' Guide, 2011-13  
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Contents >> Biomedical Measures >> Iron biomarkers >> C-reactive protein (CRP)

C-REACTIVE PROTEIN (CRP)

Definition

C-reactive protein (CRP), also referred to as an acute phase protein, provides an indication of inflammation in the body.1 Increased levels of CRP may affect other test results such as serum ferritin, as it too is an acute phase protein, and test levels increase with the presence of inflammation in the body, which is used to assess population Iron deficiency.1

The World Health Organization recommend omitting any serum results where CRP indicates the presence of an acute infection or inflammation for the interpretation of assessing the iron status of populations.2 Further information on Iron biomarkers and serum ferritin is available in the Iron Biomarkers and Ferritin pages of this product.

The CRP test measures the amount of CRP in the blood at the time of the test. Whilst the test reference range for normal CRP levels is <5 mg/L, research shows that CRP levels >10 mg/L are indicative of an acute infection or inflammation.3,4,5

Population

CRP results were obtained for persons aged 12 years and over, who participated in the National Health Measures Survey (NHMS) and provided a blood sample. Fasting was not required for this test.

Methodology

A blood sample was collected from participants and CRP levels were measured at the Douglass Hanly Moir (DHM) laboratory.

There is no consensus on the epidemiological cut off reference values for measuring CRP, however in the National Health Measures Survey, CRP levels greater than 10 mg/L have been defined as elevated CRP and indicative of inflammation or an acute infection, conservatively.

Further information about the analysis method and machines used to measure CRP 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 page of this product.

Interpretation

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

  • CRP test results do not confirm a specific diagnosis without consultation with a health professional.
  • There are a number of different test methods to measure CRP levels and each test method may produce different results. The data from this topic should therefore be used with caution when comparing CRP results from other studies using a different test method.

Comparability with other surveys

The NHMS is the first ABS survey to collect biomedical data on CRP levels.

CRP data has been collected in other non-ABS surveys. However, caution must be taken when interpreting results due to the differences in scope, assay and the instrument used, and any thresholds applied in the final analysis.

ENDNOTES

1 Gibson RS 2005, Principles of Nutritional Assessment, 2nd ed, New York: Oxford University Press.
2 World Health Organisation, 2011, Serum Ferritin Concentrations for the Assessment of Iron Status and Iron Deficiency in Populations, Geneva, Switzerland: WHO. (Vitamin and Mineral Nutrition Information System), <http://www.who.int/vmnis/indicators/serum_ferritin.pdf>, Last accessed 14/03/2014.
3 Dhingra R, Gona P, Nam B-H, D'Agostino RB Sr, Wilson PW, Benjamin EJ & O'Donnell CJ, 2007, 'C-reactive protein, inflammatory conditions, and cardiovascular disease risk', The American Journal of Medicine. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2215387/>, Last accessed 14/03/2014.
4 Lourenço BH, Cardoso MA for the ACTION Study Team, 2014, 'C-Reactive Protein Concentration Predicts Change in Body Mass Index during Childhood', PLOS ONE Journal, 9(3) e90357, doi:10.1371/journal.pone.0090357 <http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0090357>, Last accessed 14/03/2014.
5 Wieringa FT, Dijkhuisen MA, WEst CE, Northrop-Clewes & Muhilal, 2002, 'Estimation of the Effect of the Acute Phase Response on Indicators of Micronutrient Status in Indonesian Infants', The Journal of Nutrition, <http://jn.nutrition.org/content/132/10/3061.full.pdf>, Last Accessed 14/03/2014.

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