A C-reactive protein (CRP) test measures the level of this protein in your blood, which is a general marker of inflammation. While a high CRP level indicates inflammation, it does not directly diagnose cancer. Instead, it signals an inflammatory process that can stem from various causes, some of which are not serious. The liver produces CRP in response to inflammatory signals, and its elevation prompts further investigation.
What is C-Reactive Protein?
C-reactive protein is a substance produced by the liver as part of the body’s acute phase response to inflammation. Its levels rise rapidly in the blood when inflammation or infection is present. CRP is an “acute phase reactant,” meaning its concentration changes significantly during inflammatory states.
A simple blood test measures CRP levels, typically drawn from a vein. Normal values are generally below 0.3 milligrams per deciliter (mg/dL). Levels from 1 to 10 mg/dL suggest moderate inflammation, while levels above 10 mg/dL indicate a more pronounced inflammatory process, often due to serious infection or injury. A high-sensitivity CRP (hs-CRP) test can detect even lower levels, often used to assess cardiovascular disease risk.
Why Is CRP Elevated?
Numerous common conditions, unrelated to cancer, can cause elevated CRP levels. The most frequent cause of significantly high CRP is an acute infection, particularly bacterial infections like pneumonia or urinary tract infections. When the body encounters pathogens, its immune system triggers an inflammatory response, leading to a rapid increase in CRP.
Chronic inflammatory conditions also frequently elevate CRP levels. Examples include autoimmune diseases such as rheumatoid arthritis, lupus, and inflammatory bowel disease. Recent physical trauma, surgery, or burns can also cause a temporary rise as the body initiates healing. Obesity is another common driver of chronic inflammation, with excess body fat releasing inflammatory substances.
Cardiovascular diseases, including atherosclerosis and heart attacks, are also associated with increased CRP levels, as inflammation plays a role in their development. Additionally, factors such as pregnancy, particularly in later stages, and the use of birth control pills can lead to a moderate elevation. While CRP is a sensitive marker for inflammation, it does not pinpoint the exact cause or location, necessitating further investigation.
CRP and the Cancer Connection
The relationship between CRP and cancer is nuanced; elevated CRP does not serve as a diagnostic tool for cancer screening in the general population. However, inflammation and cancer are interconnected.
Chronic inflammation can contribute to cancer development and progression by creating a pro-inflammatory environment that supports tumor growth, new blood vessel formation (angiogenesis), and immune evasion. Cancer itself can also induce inflammation, leading to elevated CRP levels.
Tumor cells can secrete pro-inflammatory cytokines, such as interleukin-6 (IL-6), which stimulate the liver to produce CRP. For individuals already diagnosed with cancer, elevated CRP levels might serve as a prognostic indicator, suggesting a more aggressive disease course or poorer outcomes in various cancer types, including colorectal, lung, and breast cancers. CRP levels can also be monitored to assess a patient’s response to cancer treatments, as reductions may indicate effectiveness.
Next Steps for Elevated CRP Levels
An elevated CRP level found in a blood test warrants a consultation with a healthcare professional for further evaluation. Since CRP is a non-specific marker of inflammation, doctors will consider a patient’s complete medical history, current symptoms, and other clinical findings to determine the underlying cause. This comprehensive assessment helps differentiate between acute conditions, chronic diseases, or other factors influencing CRP levels.
Additional diagnostic tests are typically performed to investigate the source of inflammation. These may include a complete blood count (CBC), erythrocyte sedimentation rate (ESR) test, and specific tests for autoimmune conditions or infections. Imaging studies, such as X-rays or CT scans, might also be ordered if symptoms suggest a need for more detailed visualization of internal organs.
It is important to avoid self-diagnosing based solely on a single CRP result, as its elevation can stem from a wide array of benign conditions. The treatment approach will focus on addressing the root cause of the inflammation, which may involve medications, lifestyle adjustments like diet and exercise, or referrals to specialists, depending on the diagnosis.