What is C-reactive protein (CRP)?
C-reactive protein (CRP) is a protein in the blood that non-specifically increases during inflammation and infection, as well as following a heart attack, surgery, or trauma. In many instances, tissue damage causes a significant spike in the blood concentration of CRP. However, even just minimal but persistent levels of inflammation result in small CRP increases.
Why measure CRP levels?
CRP is a very sensitive marker for inflammation and infection. It tends to rise before any other symptoms (e.g. fever and pain) occur, meaning it is an excellent option to detect underlying inflammation or an infection that is yet to cause any health issues.
What is the link between CRP and heart health?
There are numerous risk factors associated with heart (cardiovascular) disease, including high cholesterol, high blood pressure, being overweight, and diabetes. However, many individuals who develop cardiovascular disease do not appear to have any of the obvious risk factors (1).
The development of a high sensitivity CRP assay has allowed for the identification of individuals that have CRP levels within the higher end of the reference range (3-10 mg/L), who are not identified in standard wide-range CRP assays (2). These slightly elevated CRP levels in otherwise healthy individuals are indicative of the development of atherosclerosis (cholesterol deposits and plaque in the blood vessel walls) and help to predict the future risk of heart attack, stroke, and peripheral artery disease (3).
In addition, measurements of CRP are useful in patients who have already suffered a myocardial infarction. Elevated CRP in these patients is associated with subsequent risk of major adverse cardiovascular events and death (4).
Ways to lower CRP
Non-pharmacological methods for reducing CRP (and the risk of heart disease) include aerobic exercise, abstaining from smoking, losing excess body weight, and following a heart-healthy diet with whole grains, reduced unhealthy fats and sodium, and lots of fruits and vegetables. Various medications are also available that have been shown to reduce CRP levels, including statins, aspirin, and vitamin E (5).
Is CRP elevated in other health conditions too?
Yes, elevated CRP is not specific to just heart health. CRP values greater than 10 mg/L occur due to infections and diseases that cause inflammation, such as:
- Lupus (immune system disease)
- Rheumatoid arthritis (swelling in the joints)
- Inflammatory bowel disease
- Osteomyelitis (bone infection)
It is important to note that although CRP tests are very useful to detect inflammation, they do not specify where the inflammation is located or what is causing it. Other tests will be required for additional information on the source and cause of the inflammation.
1. Fonseca FAH, and de Oliveira MC. (2016). High-Sensitivity C-Reactive Protein and Cardiovascular Disease Across Countries and Ethnicities. Clinics (Sao Paulo). 71(4), 235-242.
2. Pearson TA, et al. (2003). Markers of Inflammation and Cardiovascular Disease, Application to Clinical and Public Health Practice, A Statement for Healthcare Professionals from the Centers for Disease Control and Prevention and the American Heart Association. 107(3), 499-511.
3. Kamath DY, et al. (2015). High sensitivity C-reactive protein (hsCRP) & cardiovascular disease: An Indian perspective. Indian J Med Res. 142(3), 261-268.
4. Carrero JJ, et al. (2019). hsCRP Level and the Risk of Death or Recurrent Cardiovascular Events in Patients with Myocardial Infarction: a Healthcare‐Based Study. JAHA. 8.
5. Prasad K. (2006). C-reactive protein (CRP)-lowering agents. Cardiovasc Drug Rev. 24(1): 33-50.