C-Reactive Protein

C-reactive protein (CRP) is a protein found in the blood, the levels of which rise as a response to inflammation. Its physiological role is to bind to phosphocholine found on the surface of dead or dying cells (and some types of bacteria) in order to activate the complement system via c1q.

CRP is synthesized by the liver in response to factors released by fat cells (adipocytes). It is a member of the pentraxin family of proteins. It is not related to C-peptide or protein C.

Inflammation is the body's way of responding to injury or an infection. Laboratory evidence and findings from clinical and population studies suggest that inflammation is important in atherosclerosis. This is the process in which fatty deposits build up in the inner lining of arteries.

CRP is one of the acute phase proteins that increase during systemic inflammation. It’s been suggested that testing CRP levels in the blood may be an additional way to assess cardiovascular disease risk. A more sensitive CRP test, called a highly sensitive C-reactive protein (hs-CRP) assay, is available to determine heart disease risk.

The American Heart Association and the Centers for Disease Control and Prevention published a joint scientific statement in 2003 on the use of inflammatory markers in clinical and public health practice. This statement was developed after thoroughly reviewing the evidence of association between inflammatory markers (mainly CRP) and coronary heart disease and stroke.

According to the American Heart Association's website, a growing number of studies have examined whether hs-CRP can predict recurrent cardiovascular disease, stroke and death in different settings. High levels of hs-CRP consistently predict recurrent coronary events in patients with unstable angina and acute myocardial infarction (heart attack). Higher hs-CRP levels also are associated with lower survival rates in these patients. Many studies have suggested that after adjusting for other prognostic factors, hs-CRP is useful as a risk predictor.

Studies also suggest that higher levels of hs-CRP may increase the risk that an artery will reclose after it’s been opened by balloon angioplasty. High levels of hs-CRP in the blood also seem to predict prognosis and recurrent events in patients with stroke or peripheral arterial disease.

Scientific studies have found that the higher the hs-CRP levels, the higher the risk of having a heart attack. In fact, the risk for heart attack in people in the upper third of hs-CRP levels has been determined to be twice that of those whose hs-CRP level is in the lower third. These prospective studies include men, women and the elderly. Studies have also found an association between sudden cardiac death, peripheral arterial disease and hs-CRP. However not all of the established cardiovascular risk factors were controlled for when the association was examined. The true independent association between hs-CRP and new cardiovascular events hasn’t yet been established.

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