C-reactive protein

Description
C-Reactive Protein (CRP) is an acute phase response protein that indicates blood levels of inflammation. CRP levels rise as part of the immune response to infection and injury and may be elevated due to chronic conditions, like diabetes, psoriasis and asthma (http://labtestsonline.org/understanding/analytes/crp/sample.html).

C-reactive protein is considered one of the best measures of the acute phase response to an infectious disease or other cause of tissue damage and inflammation. The level of CRP can jump a thousand-fold in response to inflammation. It drops relatively quickly as soon as the inflammation passes (http://labtestsonline.org/understanding/analytes/crp/sample.html).

Significance of Measurement
A high level of CRP in the blood suggests an acute infection or inflammation. A blood level above 10 mg/dL is considered indicative of acute illness.

High levels of CRP may also serve as an indicator of several conditions, including rheumatoid arthritis, rheumatic fever, tuberculosis, pneumonia, and lupus. CRP levels are also related to hormone levels in women, so that higher CRP can be detected during the last half of pregnancy and in women using oral contraceptives or hormone replacement therapy.

Recently, research has suggested that moderate levels of CRP, particularly those between 3 and 10 mg/dL (Ridker & Cook, 2004), are related to the development of cardiovascular disease (Danesh et al., 1998, 1999, 2000; Ridker et al., 2000) and cardiac events, including heart attack (Ridker et al., 1997) and stroke (Ridker et al., 2000). Moderate levels of CRP have also been has also been related to arthritis (Sowers et al., 2002), cancer (Erlinger et al., 2004), mortality (Harris et al., 1999; Reuben et al., 2002), physical and cognitive decline (Reuben et al., 2002; Weaver et al., 2000).

Method of Measurement
CRP can be measured with blood samples or blood spots. The CRP test measures the concentration in blood plasma of a special type of protein produced in the liver that is present during episodes of acute inflammation or infection

There is a high sensitivity CRP test (hs-CRP) in addition to the regular CRP test. The hs-CRP measures very low amounts of CRP in the blood and is typically used to assess the level of risk for heart problems. Most hospitals do not perform the high sensitivity CRP test used in research settings
(http://labtestsonline.org/understanding/analytes/crp/sample.html).

References
· Danesh, J., Collins, R., Appleby, P., & Peto, R. (1998). Association of fibrinogen, c-reactive protein, albumin, or leukocyte count with coronary heart disease: Meta-analyses of prospective studies. Journal of the American Medical Association, 270, 1477-1482.
· Danesh, J., Muir, J., Wong, Y., Ward, M., Gallimore, J.R., & Pepys, M.B. (1999). Risk factors for coronary heart disease and acute-phase proteins: A population based study. European Heart Journal, 20, 954-959.
· Danesh, J., Whincup, P., Walker, M., Lennon, L., Thomson, A., Appleby, P., et al (2000). Low grade inflammation and coronary heart disease: Prospective study and updated meta-analysis. British Medical Journal, 321, 199-204.
· Erlinger, T.P., Platz, E.A., Rafai, N., & Helzlsouer, K.J. (2004). C-reactive protein and the risk of incident colorectal cancer. Journal of the American Medical Association, 291, 585-590.
· Harris, T.B., Ferrucci, L., Tracy, R.P., Corti, M.C., Wacholder, S., Ettinger, W.H., et al. (1999). Associations of elevated interleukin-6 and C-reactive protein levels with mortality in the elderly. American Journal of Medicine, 106, 506-512.
· Lab Tests Online. (n.d.). C-Reactive Protein. Retrieved March 24, 2005, from http://labtestsonline.org/understanding/analytes/crp/sample.html
· Reuben, D.B., Chen, A.I., Harris, T., Ferrucci, L., Rowe, J., Tracy, R., & Seeman, T. (2002). Peripheral blood markers of inflammation predict mortality and functional decline in high-functioning community-dwelling older persons. Journal of the American Geriatrics Society, 50, 638-644.
· Ridker, P.M., & Cook, N. (2004). Clinical usefulness of very high and very low levels of c-reactive protein across the full range of Framingham Risk Scores. Circulation, 109, 1955-1959.
· Ridker, P.M., Hennekens, C.H., Buring, J.E., & Rifai, N. (2000). C-reactive protein and other markers of inflammation in the prediction of cardiovascular disease in women. New England Journal of Medicine, 342, 836-843.
· Ridker, P.M., Cushman, M., Stampfer, M.J. Tracy, R.P., & Hennekens, C.H. (1997). Inflammation, aspirin, and the risk of cardiovascular disease in apparently healthy men. New England Journal of Medicine, 336, 973-979.
· Sowers, M., Jannausch, M., Stein, E., Jamadar, D., Hochberg, M., & Lachance, L. (2002). C-reactive protein as a biomarker of emergent osteoarthritis. Osteoarthritis & Cartilage, 10, 595-601.
· Weaver, J.D., Huang, M.H., Albert, M., Harris, T., Rowe, J.W., & Seeman, T.E. (2002). Interleukin-6 and risk of cognitive decline. Neurology, 59, 371, 378.