C-reactive protein (CRP) is a plasma protein, an acute phase protein produced by the liver.
History and nomenclature
CRP was originally discovered by Tillett and Francis in 1930 as a substance in the serum of patients with acute inflammation that reacted with the C polypeptide of pneumococcus.
CRP is a member of the class of acute phase reactants as its levels rise dramatically during inflammatory processes occurring in the body. Measuring and charting C-reactive protein values can prove useful in determining disease progress or the effectiveness of treatments. CRP is therefore a marker of inflammation. It has recently been discovered that CRP also plays a role in heart disease.
It is thought to assist in complement binding to foreign and damaged cells and affect the humoral response to disease.
Role in cardiovascular disease
Recent research suggests that patients with elevated basal levels of CRP are at an increased risk for hypertension and cardiovascular disease, although recent research (http://content.nejm.org/cgi/content/abstract/350/14/1387) suggests the correlation is moderate.
The amount of CRP produced by the body varies from person to person, and this is affected by an individual's genetic makeup (accounting for almost half of the variation in CRP levels between different people) and lifestyle. Higher CRP levels tend to be found in individuals who smoke, have high blood pressure, are overweight and don't exercise, whereas lean, athletic individuals tend to have lower CRP levels.
Research shows that too much inflammation can sometimes have adverse effects on the blood vessels which transport oxygen and nutrients throughout our bodies. Atherosclerosis, which involves the formation of fatty deposits or plaques in the inner walls of the arteries, is now considered in many ways an inflammatory disorder of the blood vessels, similar to how arthritis is an inflammatory disorder of the bones and joints. Inflammation not only affects the atherosclerotic phase of heart disease, but also the rupturing of plaques which can then travel and interfere with blood flow, causing a heart attack.
Many studies have shown an association between elevated levels of inflammatory markers (including CRP) and the future development of heart disease. This is true even for apparently healthy men and women who have normal cholesterol levels. The reason CRP can be used by physicians as part of the assessment of a patient's risk for heart disease, is because it is a stable molecule and can be easily measured with a simple blood test. In patients already suffering from heart disease, doctors can use CRP levels to determine which patients are at high risk for recurring coronary events.
To measure the CRP level, a "high-sensitivity" CRP or hs-CRP test needs to be performed and analyzed by a laboratory. This is a simple blood test designed for greater accuracy in measuring CRP, which allows the physician to use the result in the assessment of cardiovascular risk.