C-Reactive Protein, High Sensitivity, Serum
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
C-reactive protein (CRP) is 1 of the most sensitive acute-phase reactants. Plasma CRP levels can increase dramatically (100-fold or more) after severe trauma, bacterial infection, inflammation, surgery, or neoplastic proliferation. Measurement of CRP has been used historically to assess activity of inflammatory disease, to detect infections after surgery, to detect transplant rejection, and to monitor these inflammatory processes. While assays for CRP have been available for many years, the traditional assays lack the sensitivity to measure basal levels of CRP.
In the mid-1990s, more sensitive methods for measurement of CRP were introduced. These methods, referred to as high sensitivity CRP (hs-CRP), can accurately measure basal levels of CRP throughout the currently accepted cardiovascular risk assessment range (0.20-10.0 mg/L).
These hs-CRP assays were used to assess outcomes in patients with unstable angina and showed that hs-CRP values in the upper tertile (>3.0 mg/L) were associated with increased risk of developing myocardial infarction (1,2). Data from prospective studies monitoring hs-CRP in apparently healthy populations also has been published. All prospective studies reported to date have been positive, with adjusted relative risks of developing cardiovascular disease or ischemic events ranging from 2.3 to 4.8 in the highest quartile or quintile of data versus the lowest quartile or quintile (3-6). It also has been shown that hs-CRP is additive with total cholesterol, LDL and HDL, as well as the Framingham 10-year risk score, with respect to risk prediction (7-8).
More aggressive treatment strategies may be pursued in patients determined to be at increased risk by hs-CRP values.
Assessment of risk of developing myocardial infarction in patients presenting with acute coronary syndromes
Assessment of risk of developing cardiovascular disease or ischemic events in individuals who do not manifest disease at present
Increased high sensitivity C-reactive protein values are associated with increased risks of cardiovascular disease or cardiovascular events.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
C-reactive protein (CRP) is an acute-phase reactant. A single test for high sensitivity CRP (hs-CRP) may not reflect an individual patient's basal hs-CRP level. Repeat measurement may be required to firmly establish an individual's basal hs-CRP concentration. The lowest of the measurements should be used as the predictive value.
Because CRP is an acute-phase reactant, measurements in apparently healthy individuals may not truly reflect the basal level if inflammation is present.
This hs-CRP assay should be used as a means to assess risk of cardiovascular disease or events. A different CRP test (CRP/9731 C-Reactive Protein [CRP], Serum) should be used to monitor or assess other inflammatory disorders.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Low risk: <1.0 mg/L
Average risk: 1.0-3.0 mg/L
High risk: >3.0 mg/L
Acute inflammation: >10.0 mg/L
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Haverkate F, Thompson SG, Pyke SD, et al: Production of C-reactive protein and risk of coronary events in stable and unstable angina. European Concerted Action on Thrombosis and Disabilities Angina Pectoris Study Group. Lancet 1997;349(9050):462-466
2. Rebuzzi AG, Quaranta G, Liuzzo G, et al: Incremental prognostic value of serum levels of troponin T and C-reactive protein on admission in patients with unstable angina pectoris. Am J Cardiol 1998;82(6):715-719
3. Ridker PM, Cushman M, Stampfer MJ, et al: Inflammation, aspirin, and the risk of cardiovascular disease in apparently healthy men. N Engl J Med 1997;336(14):973-979
4. Tracy RP, Lemaitre RN, Psaty BM, et al: Relationship of C-reactive protein to risk of cardiovascular disease in the elderly. Results from the Cardiovascular Health Study and the Rural Health Promotion Project. Arterioscler Throm Vasc Biol 1997;17(6):1121-1127
5. Ridker PM, Buring JE, Shih J, et al: Prospective study of C-reactive protein and the risk of future cardiovascular events among apparently healthy women. Circulation 1998;98(8):731-733
6. Koenig W, Sund M, Frohlich M, et al: C-reactive protein, a sensitive marker of inflammation, predicts future risk of coronary heart disease in initially healthy middle-aged men: results from the MONICA (Monitoring Trends and Determinants in Cardiovascular Disease) Augsburg Cohort Study, 1984 to 1992. Circulation 1999;99(2):237-242
7. Ridker PM, Glynn RJ, Hennekens CH: C-reactive protein adds to the predictive value of total and HDL cholesterol in determining risk of first myocardial infarction. Circulation 1998;97(20):2007-2011
8. Ridker PM, Rifai N, Rose L, et al: Comparison of C-reactive protein and low-density lipoprotein cholesterol levels in the prediction of first cardiovascular events. N Engl J Med 2003;347(20):1557-1565
9. Pearson TA, Mensah GA, Alexander RW, et al: Markers of inflammation and cardiovascular disease; application to clinical and public health practice; A statement for healthcare professionals from the Center for Disease Control and Prevention and the American Heart Association. Circulation 2003;107(3):499-511
10. Ridker PM, Danielson E, Fonseca FAH, et al: Rosuvastatin to Prevent Vascular Events in Men and Women with Elevated C-Reactive Protein. N Engl J Med 2008;359(21):2195-2207