From the Guidelines
C-Reactive Protein (CRP) elevation is primarily caused by inflammation, infection, and tissue damage in the body, with the most common causes including bacterial infections, viral infections, autoimmune disorders, and tissue damage from surgery, trauma, or heart attacks, as well as obesity, smoking, and chronic conditions like diabetes and kidney disease. The causes of CRP elevation can be broadly categorized into:
- Infections, such as bacterial infections (e.g., pneumonia, urinary tract infections, and sepsis) and viral infections, which can cause varying degrees of CRP elevation, with bacterial infections typically causing higher elevations (often >100 mg/L) compared to viral infections (usually <20 mg/L) 1
- Autoimmune disorders, such as rheumatoid arthritis, lupus, and inflammatory bowel disease, which can cause chronic inflammation and CRP elevation 1
- Tissue damage, such as from surgery, trauma, or heart attacks, which can cause acute inflammation and CRP elevation 1
- Chronic conditions, such as obesity, smoking, diabetes, and kidney disease, which can cause low-grade inflammation and CRP elevation 1
- Other factors, such as certain cancers and medications, such as hormone replacement therapy and some oral contraceptives, which can also cause CRP elevation
It is essential to note that CRP elevation is not specific to any particular condition, and additional diagnostic testing is typically needed to determine the underlying cause. The degree of CRP elevation can provide clues about the severity of inflammation, but it is crucial to consider the clinical context and other diagnostic findings to make an accurate diagnosis. As stated in a study published in 2020, CRP values >10 mg/L are not always indicative of acute infection/injury, and a more thoughtful approach is needed to interpret CRP results 1.
From the Research
Causes of CRP Elevation
The causes of C-Reactive Protein (CRP) elevation can be attributed to various inflammatory and infectious processes. Some of the key causes include:
- Inflammatory diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) 2
- Infections, including sepsis and acute bacterial infections 2, 3
- Chronic inflammatory diseases, such as cardiovascular disease, type 2 diabetes mellitus, and age-related macular degeneration 4
- Gastrointestinal diseases, including Crohn's disease and acute pancreatitis 5
- Trauma and tissue destruction 6, 3
- Necrosis and inflammation 3
Mechanism of CRP Elevation
CRP is synthesized by hepatocytes in response to pro-inflammatory cytokines, such as interleukin-6, tumor-necrosis-factor-alpha, and interleukin-1beta 5, 6. The levels of CRP increase rapidly in response to inflammatory and infectious processes, and decrease with the resolution of the condition 6. The measurement of CRP is widely used to monitor various inflammatory states, and its function is related to its role in the innate immune system 6.
Clinical Significance of CRP Elevation
Elevated CRP levels have been associated with an increased risk of various diseases, including colorectal cancer, and are a marker of poor prognosis, indicating more advanced disease and possibly reduced survival 5. CRP is also useful as a laboratory marker to predict prognosis and relapse in patients with certain diseases, such as Crohn's disease and acute pancreatitis 5.