From the Guidelines
Elevated C-reactive protein (CRP) levels are primarily caused by inflammation or infection in the body, and identifying and treating the underlying cause is essential to prevent tissue damage and disease progression. The causes of elevated CRP can be categorized into several groups, including:
- Infections such as pneumonia, urinary tract infections, and sepsis
- Inflammatory conditions like rheumatoid arthritis, inflammatory bowel disease, and lupus
- Cardiovascular issues including heart attacks, strokes, and atherosclerosis
- Tissue damage from surgery, burns, or trauma
- Lifestyle factors such as obesity, smoking, lack of exercise, and poor sleep
- Certain medications like hormone replacement therapy and some birth control pills
- Chronic diseases including diabetes, cancer, and kidney disease
According to a recent study 1, CRP values >10 mg/L are not always indicative of acute infection or injury, and a more thoughtful approach is needed to recognize the influence of demographic, behavioral, and technical factors. Another study 1 found that CRP is a downstream marker of inflammation that has multiple effects, including complement binding, augmentation of expression of adhesions molecules, and decreased expression of the vasodilator endothelial nitric oxide synthase.
It is essential to identify and treat the underlying cause of elevated CRP to prevent tissue damage and disease progression. A study 1 recommended that CRP results should be expressed only as milligrams per liter and expressed to 1 decimal point, and risk assessment should be modeled after the lipids approach via 3 risk categories: low risk, average risk, and high risk. However, the most recent and highest quality study 1 suggests that a more thoughtful approach is needed to recognize the influence of demographic, behavioral, and technical factors on CRP values.
Some key points to consider when evaluating elevated CRP levels include:
- CRP is produced by the liver in response to inflammatory cytokines, particularly interleukin-6
- CRP is a reliable marker of systemic inflammation
- Persistent inflammation can lead to tissue damage and disease progression
- Identifying and treating the underlying cause of elevated CRP is essential to prevent tissue damage and disease progression.
From the Research
Causes of Elevated C-Reactive Protein (CRP)
Elevated levels of C-Reactive Protein (CRP) have been observed in various conditions, including:
- Infections, such as bacterial, viral, and mycotic meningitis 2, 3, 4, 5
- Autoimmune diseases, such as Systemic Lupus Erythematosus and rheumatoid arthritis 2, 6
- Neurodegenerative disorders 2
- Malignancies, including breast, colorectal, ovarian, prostate, and lung cancers 2
- Cardiovascular disease, owing to its role as an inflammatory marker in atherosclerosis, coronary artery disease, and peripheral arterial disease 2
Specific Causes of Highly Elevated CRP Levels
Highly elevated CRP levels (≥500 mg/L) have been associated with:
- Infectious diseases, particularly bacterial infections, with Gram-positive cocci and Gram-negative bacilli being common causative microorganisms 5
- Immunocompromised conditions, with 52% of patients having an underlying immunocompromised condition 5
- Respiratory, urinary, and abdominal infections, with respiratory infections being the most common site of infection 5
CRP Levels in Different Conditions
- Elevated CRP levels have been observed in patients with viral and atypical bacterial infections, but no significant differences were found between the two types of infections 4
- High CRP levels have been associated with disease activity in rheumatoid arthritis, while insufficient CRP levels have been implicated in the development of Systemic Lupus Erythematosus 6
- Extremely high CRP levels (≥500 mg/L) are highly related to bacterial infections and are associated with a high mortality rate 5