From the Guidelines
Mildly elevated CRP levels can be caused by a variety of factors, including low-grade inflammation, minor infections, obesity, smoking, or chronic conditions, and it is essential to consider the clinical context to determine the underlying cause.
Possible Causes of Mildly Elevated CRP
- Low-grade inflammation
- Minor infections, such as mild respiratory infections, early stages of bacterial infections, urinary tract infections, or gingivitis
- Chronic conditions, including rheumatoid arthritis, inflammatory bowel disease, or cardiovascular disease
- Lifestyle factors, such as obesity (particularly visceral fat), smoking, lack of exercise, poor sleep, and stress, which contribute to chronic low-grade inflammation
- Medications, like hormone replacement therapy or oral contraceptives, which may slightly increase CRP levels
- Age-related inflammation (inflammaging) in older adults, as noted in studies 1
Importance of Clinical Context
When CRP is mildly elevated, it is crucial to consider the clinical context, as isolated mild elevations without symptoms may not require treatment. However, persistent elevations warrant further investigation to identify the underlying cause. CRP is produced by the liver in response to inflammatory cytokines and serves as a general marker of inflammation rather than indicating a specific disease. According to a study published in 2020 1, many factors influence circulating CRP values that are unrelated to "pathological" processes, and it may not always be advisable to routinely exclude participants solely on the basis of one high CRP value. Another study from 2011 1 highlights the importance of inflammation in the development of cardiovascular disease, with CRP levels being an independent predictor of CVD events.
Considerations for Further Investigation
Further investigation is necessary to determine the underlying cause of mildly elevated CRP levels, especially if the elevation is persistent. This may involve assessing lifestyle factors, such as diet, exercise, and sleep, as well as evaluating for chronic conditions or minor infections. The study from 2020 1 suggests that many factors can influence CRP values, and a thorough evaluation is necessary to determine the cause of the elevation.
From the Research
Possible Causes of Mildly Elevated CRP
- Inflammation: C-reactive protein (CRP) is a sensitive biomarker of inflammation, and elevations in plasma/serum CRP level have been associated with various disease states 2.
- Infection: CRP plays a role in host defense against bacterial infection, and its levels may be elevated in response to infection 3.
- Autoimmune disease: CRP has been implicated in the pathogenesis of autoimmune diseases, and its levels may be elevated in patients with these conditions 3.
- Cardiovascular disease: Elevated CRP levels have been linked to an increased risk of cardiovascular disease 2, 4.
- Cancer: CRP levels may be elevated in patients with certain types of cancer 2, 4.
Factors that May Influence CRP Levels
- Nonsteroidal anti-inflammatory drugs (NSAIDs): Some NSAIDs, such as naproxen, may decrease CRP levels, while others, such as lumiracoxib, may increase CRP levels 5.
- Statins: These drugs may lower CRP concentrations, but their effect on the relationship between CRP and health-related quality of life is unclear 6.
- Aspirin: The effect of aspirin on CRP levels and its relationship to health-related quality of life is unclear 6.