From the Guidelines
Elevated C-reactive protein (CRP) levels can be caused by various inflammatory conditions, including infections, autoimmune disorders, inflammatory bowel diseases, and tissue damage from injuries, surgeries, or heart attacks, as well as chronic conditions like obesity, diabetes, and cardiovascular disease, as supported by recent studies 1.
Causes of Elevated CRP
Some of the key causes of elevated CRP include:
- Infections (bacterial, viral, or fungal)
- Autoimmune disorders like rheumatoid arthritis or lupus
- Inflammatory bowel diseases such as Crohn's disease or ulcerative colitis
- Tissue damage from injuries, surgeries, or heart attacks
- Chronic conditions like obesity, diabetes, and cardiovascular disease
- Certain medications, smoking, and lack of sleep
Mechanism of CRP Elevation
CRP is produced by the liver as part of the acute phase response to inflammation, and its levels can rise rapidly within hours of an inflammatory stimulus, making it a useful but non-specific marker of inflammation, as noted in studies 1.
Clinical Implications
When CRP is elevated, further diagnostic testing is typically needed to determine the underlying cause, as the elevation itself doesn't identify the specific source of inflammation, and treatment focuses on addressing the underlying condition rather than the CRP level itself, as recommended in guidelines 1.
Recent Findings
Recent studies have highlighted the importance of considering demographic, behavioral, and technical factors when interpreting CRP values, and have suggested that CRP values >10 mg/L are not always indicative of acute infection or injury, but may be influenced by other factors such as age, sex, and socioeconomic status, as discussed in 1.
From the Research
Causes of Elevated CRP
Elevated C-reactive protein (CRP) levels can be caused by various factors, including:
- Inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, as shown in studies 2, 3, 4
- Rheumatoid arthritis, where CRP is used as a marker of systemic inflammation 5
- Systemic lupus erythematosus (SLE), where autoantibodies to CRP are commonly found 6
- Other conditions that cause systemic inflammation, such as infections and autoimmune disorders
Inflammatory Bowel Diseases
Inflammatory bowel diseases, including Crohn's disease and ulcerative colitis, can cause elevated CRP levels due to the chronic inflammation in the gut. Studies have shown that CRP levels are higher in Crohn's disease than in ulcerative colitis, and that CRP levels correspond closely with clinical and pathological indices of relapse, remission, and response to therapy in patients with Crohn's disease 2, 3, 4.
Rheumatoid Arthritis
In rheumatoid arthritis, CRP is used as a marker of systemic inflammation and can be elevated due to the chronic inflammation in the joints. CRP has also been associated with the risk of comorbidities such as cardiovascular disease, diabetes, and metabolic syndrome in patients with rheumatoid arthritis 5.
Systemic Lupus Erythematosus (SLE)
In SLE, autoantibodies to CRP are commonly found, but it is not clear whether this affects CRP levels or has other biological potentials of pathophysiological interest in SLE 6.