Monitoring Inflammation : PV, ESR or CRP?

The ESR is the time-honoured test used to measure the acute phase response to "screen" for the presence of infection or inflammation and to monitor "disease activity". Measurement of plasma viscosity (PV) and specific proteins such as CRP are more recent innovations.

For general screening purposes and monitoring of inflammatory disorders the PV, ESR and CRP is convenient and readily available in the laboratory. It should be interpreted together with the full blood count, eg evidence of "secondary anaemia" or other indicators of inflammation, to give a more complete picture.  PV and CRP have been largely used for the rheumatic and connective tissue disorders including cranial arteritis, and inflammatory bowel disease.

Test Test reflects the presence of: Effect of anaemia Advantages and Disadvantages
ESR fibrinogen, immunoglobulins and abnormal proteins rise in ESR no technique for calibration to test for accuracy; poor reproducibility; affected by anaemia.
PV macro-molecules e.g. fibrinogen and globulins no effect automatable; measurement can be made on stored blood samples (non refrigerated)
CRP precise measurements of C-Reactive Protein no effect automatable; very sensitive early but short lived indicator

Which acute phase test should be used in practise?

Cranial arteritis is a condition in which the ESR and PV have been particularly used to confirm clinical suspicion and initiate urgent steroid therapy. Comparative studies have failed to show an advantage to either technique and a normal result should never dissuade the clinician from starting steroids if the clinical picture is highly suggestive.

A raised CRP is particularly useful for the identification of patients with occult bacterial infection eg endocarditis. CRP has been well evaluated for this purpose and is readily available. It may be useful to perform this test sequentially eg daily, in this context.

Test Age and Sex Reference Range Sample Requirement
ESR men <50 yrs, women < 50 yrs, both sexes> 50 yrs 05 mm/h, 0-7 mm/h, <30 mm/h 2 mL EDTA
PV independent of age and sex 1.5-1.72 mPa 2 mL EDTA
CRP variable but constant within individuals <10 mg/L 2 mL serum tube

Page updated: 20/04/09 | Updated by: Dr. Julian Barth

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