C-REACTIVE PROTEIN (CRP) - serum

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Specimen: 5 mL blood in plain tube.

Method: Immunoassay.

Reference Interval: <5 mg/L.

Application: Assessment of acute phase reaction in inflammatory, infective and neoplastic disorders; monitoring disease activity, particularly in inflammatory arthritis; monitoring patients after premature rupture of the membranes, for developing infection; assessment of risk factors for myocardial infarction. Marginally raised CRP has been demonstrated to be an independent risk factor for coronary artery disease; however, the applicability of measuring serum CRP for screening in asymptomatic populations for coronary artery disease risk remains unclear.

Interpretation: Elevation indicates acute phase response or active disease in chronic inflammatory disorders. CRP is a more sensitive early indicator of an acute phase response than is the ESR. It also returns towards normal more rapidly with improvement or resolution of the disease process. The test is less sensitive than the ESR for some disorders eg ulcerative colitis, SLE. In patients at risk for myocardial infarction and without other causes of an acute phase response, the presence of slightly elevated or even high normal CRP indicates a greater risk of myocardial infarction than previously assessed. This use of CRP requires a special, high sensitivity assay. See also ERYTHYROCYTE SEDIMENTATION RATE and ACUTE PHASE REACTANTS .

Reference: Young B et al. Pathology 1991; 23: 118-124.

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