C-reactive Protein (CRP), Cardiac C-reactive Protein, (High Sensitivity C-reactive Potein)
C-reactive protein is a plasma protein that rises in the blood with the inflammation from certain conditions. C-reactive protein (CRP) is one of the plasma proteins known as acute- phase proteins: proteins whose plasma concentrations increase (or decrease) by 25% or more during inflammatory disorders. CRP can rise as high as 1000-fold with inflammation. Conditions that commonly lead to marked changes in CRP include infection, trauma, surgery, burns, inflammatory conditions, and advanced cancer. Moderate changes occur after strenuous exercise, heatstroke, and childbirth. Small changes occur after psychological stress and in several psychiatric illnesses. CRP is therefore a test of value in medicine, reflecting the presence and intensity of inflammation, although an elevation in C-reactive protein is not the telltale diagnostic sign of any one condition. Since inflammation is believed to play a major role in the development of coronary artery disease, markers of inflammation have been tested in respect to heart health. CRP was found to be the only marker of inflammation that independently predicts the risk of a heart attack. (N Engl J Med 2000;342:836-43.) A special test called the “High Sensitivity C-reactive Protein” or “Cardiac C-reactive Protein” strongly suggests inflammation in the vascular system, usually a result of actively progressing atherosclerosis.
Measuring and charting C-reactive protein values can prove useful in determining disease progress or the effectiveness of treatments. Viral infections tend to give a lower CRP level than bacterial infection. CRP rises up to 50,000 fold in acute inflammation, such as infection. It rises above normal limits within 6 hours, and peaks at 48 hours. Its half-life is constant, and therefore its level is mainly determined by the rate of production (and hence the severity of the precipitating cause). Serum amyloid A is a related acute phase marker that responds rapidly in similar circumstances. Arterial damage is thought to result from inflammation due to chemical insults or bacterial toxins. CRP is a general marker for inflammation and infection, so it can be used as a very rough approximation pf heart disease risk. Since many things can cause elevated CRP, this is not a specific prognostic indicator, neverhteless a level above 2.4 mg/l has been associated with a doubled risk of a coronary event compared to levels below 1 mg/l. Recent research suggests that patients with elevated basal levels of CRP are at an increased risk for diabetes, hypertension and cardiovascular disease.