From the Guidelines
Elevated C-Reactive Protein (CRP) levels are primarily caused by inflammation or infection in the body, and it is essential to consider the clinical context and potential influencing factors, such as demographic, behavioral, and technical factors, when interpreting CRP values 1. When evaluating elevated CRP levels, it is crucial to recognize that CRP values >10 mg/L are not always indicative of acute infection or injury, but rather can be influenced by various factors, including age, sex, socioeconomic status, race, body mass index, exercise, diet, sleep, and medication use 1. Some common causes of elevated CRP levels include:
- Acute infections (bacterial, viral, fungal)
- Chronic inflammatory conditions (e.g., rheumatoid arthritis, inflammatory bowel disease)
- Tissue injury or trauma
- Some cancers
- Cardiovascular diseases (e.g., atherosclerosis, heart attack)
- Obesity
- Smoking CRP is produced by the liver in response to inflammatory cytokines, particularly interleukin-6, and is part of the body's acute phase response to inflammation 1. To accurately interpret elevated CRP levels, it is essential to consider the clinical context and potentially perform additional tests, such as a clinical index of the acute phase response/infection, or evaluating hepatic health with a routine blood biochemistry panel 1. A thoughtful approach that recognizes the influence of various factors on CRP values is necessary, rather than solely relying on a cut-off value of 10 mg/L to determine the presence of an acute pathological process 1.
From the Research
Causes of Elevated C-Reactive Protein (CRP) Levels
Elevated CRP levels have been observed in various conditions, including:
- Infections 2, 3, 4
- Autoimmune diseases, such as Systemic Lupus Erythematosus and rheumatoid arthritis 2, 3, 5
- Neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease 3
- Malignancies, including breast, colorectal, ovarian, prostate, and lung cancers 2, 4
- Cardiovascular disease, owing to its role as an inflammatory marker in atherosclerosis, coronary artery disease, and peripheral arterial disease 2, 3
- Chronic inflammatory and neurodegenerative diseases, such as cardiovascular disease, type 2 diabetes mellitus, age-related macular degeneration, hemorrhagic stroke 3
- Gastrointestinal diseases, such as Crohn's disease and acute pancreatitis 4
- Chronic kidney disease, heart failure, liver disease, psoriasis, rheumatoid arthritis, and chronic obstructive pulmonary disease 6
- Diabetes, prior myocardial infarction (MI), hypertension, and sleep apnoea, which can be mostly explained by adiposity alone 6
Factors Influencing CRP Levels
- Adiposity, which can explain elevated CRP levels in certain conditions, such as diabetes, prior myocardial infarction (MI), hypertension, and sleep apnoea 6
- Liver dysfunction, which can result in lower CRP levels during active immune-mediated inflammatory diseases (IMIDs) 5
- Pro-inflammatory cytokines, such as interleukin-6, tumor-necrosis-factor-alpha, and interleukin-1beta, which stimulate the production of CRP during an acute-phase response 4