Saturday, November 1, 2008

The Role of C-Reactive Protein

Ribbon structure of C-reactive Protien

Inflammation, Heart Disease and Stroke: The Role of C-Reactive Protein

How does inflammation relate to heart disease and stroke risk?
“Inflammation” is the process by which the body responds to injury or an infection. Laboratory evidence and findings from clinical and population studies suggest that inflammation is important in atherosclerosis (ath”er-o-skleh-RO’sis). This is the process in which fatty deposits build up in the inner lining of arteries.

C-reactive protein (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

What’s the role of hs-CRP in predicting new cardiovascular events?

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.

What causes low-grade inflammation?

The major injurious factors that promote atherogenesis — cigarette smoking, hypertension, atherogenic lipoproteins, and hyperglycemia — are well established. These risk factors give rise to a variety of noxious stimuli that cause the release of chemicals and the activation of cells involved in the inflammatory process. These events are thought to contribute not only to the formation of plaque but may also contribute to its disruption resulting in the formation of a blood clot. Thus, virtually every step in atherogenesis is believed to involve substances involved in the inflammatory response and cells that are characteristic of inflammation.

In addition, there is also research that indicates an infection — possibly one caused by a bacteria or a virus — might contribute to or even cause atherosclerosis. The infectious bacteria, Chlamydia pneumoniae (klah-MID'e-ah nu-MO'ne-i), has been shown to have a significant association to atherosclerotic plaque. The herpes simplex virus has also been proposed as an initial inflammatory infectious agent in atherosclerosis.
The notion that chronic infection can lead to unsuspected disease isn't foreign to most doctors. For example, bacterial infection with Helicobacter pylori is now known to be the major cause of stomach ulcers. The treatment for this condition now routinely includes antibiotic therapy.

Should I have my CRP level measured?

If a person’s cardiovascular risk score — judged by global risk assessment — is low (the possibility of developing cardiovascular disease is less than 10 percent in 10 years), no test is immediately warranted. If the risk score is in the intermediate range (10–20 percent in 10 years), such a test can help predict a cardiovascular or stroke event and help direct further evaluation and therapy. However, the benefits of such therapy based on this strategy remain uncertain. A person with a high risk score (greater than 20 percent in 10 years) or established heart disease or stroke should be treated intensively regardless of hs-CRP levels.

What is the normal range of hs-CRP level?

If hs-CRP level is lower than 1.0 mg/L, a person has a low risk of developing cardiovascular disease.

If hs-CRP is between 1.0 and 3.0 mg/L, a person has an average risk.

If hs-CRP is higher than 3.0 mg/L, a person is at high risk.

If, after repeated testing, patients have persistently unexplained, markedly elevated hs-CRP (greater than 10.0 mg/L), they should be evaluated to exclude noncardiovascular causes. Patients with autoimmune diseases or cancer, as well as other infectious diseases, may also have elevated CRP levels.

Source of Article: American Heart Association
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