C-Reactive Protein
Also known as: CRP, hs-CRP
What Does C-Reactive Protein Measure?
C-Reactive Protein (CRP) is a protein produced by the liver in response to inflammation anywhere in the body. When measured as high-sensitivity CRP (hs-CRP), the test can detect even very low levels of this protein in the bloodstream, making it a sensitive indicator of subtle, chronic inflammation. The test essentially measures how much of this inflammatory signaling protein is circulating in your blood at the time of the test.
Why Does C-Reactive Protein Matter?
CRP is one of the most widely used markers of systemic inflammation and is a powerful predictor of cardiovascular disease risk, particularly when measured using the high-sensitivity version. Chronically elevated CRP levels have been linked to heart attacks, stroke, type 2 diabetes, metabolic syndrome, and certain cancers. Clinicians use it to assess infection severity, monitor autoimmune and inflammatory diseases like rheumatoid arthritis or lupus, and evaluate a patient's response to treatment. Because inflammation underlies so many chronic diseases, CRP serves as an important early warning signal for conditions that may not yet be causing obvious symptoms.
Normal Ranges
Males
Standard CRP: <10 mg/L (no active inflammation); hs-CRP: <1.0 mg/L (low cardiovascular risk), 1.0–3.0 mg/L (moderate risk), >3.0 mg/L (high risk)
Females
Standard CRP: <10 mg/L (no active inflammation); hs-CRP: <1.0 mg/L (low cardiovascular risk), 1.0–3.0 mg/L (moderate risk), >3.0 mg/L (high risk)
Children
Varies by age; generally <10 mg/L for standard CRP; hs-CRP reference ranges less established in pediatric populations
Causes of High Levels
- Bacterial or viral infections (e.g., pneumonia, sepsis, COVID-19)
- Autoimmune and inflammatory conditions (e.g., rheumatoid arthritis, lupus, inflammatory bowel disease)
- Obesity and excess visceral (belly) fat, which generates chronic low-grade inflammation
- Cardiovascular disease and atherosclerosis (plaque buildup in arteries)
- Recent surgery, trauma, or tissue injury
- Smoking and chronic exposure to environmental toxins
Causes of Low Levels
- Optimal metabolic health with no active infection or inflammation
- Regular physical activity and a healthy body weight
- Anti-inflammatory diet rich in whole foods, fruits, and vegetables
How to Improve Your C-Reactive Protein
Diet
- Follow a Mediterranean-style diet rich in olive oil, fatty fish, legumes, nuts, and colorful vegetables to reduce systemic inflammation
- Increase omega-3 fatty acid intake through fatty fish (salmon, mackerel, sardines) at least 2–3 times per week
- Reduce consumption of ultra-processed foods, refined sugars, and trans fats, which are known to elevate CRP
- Add anti-inflammatory spices like turmeric (curcumin) and ginger to daily meals
- Increase dietary fiber intake through whole grains, legumes, and vegetables to support gut health and lower inflammation
Supplements
- Omega-3 fish oil: 2–4 grams of EPA+DHA per day has been shown in clinical trials to significantly lower CRP
- Curcumin (turmeric extract): 500–1000 mg per day with piperine for enhanced absorption to reduce inflammatory markers
- Magnesium: 300–400 mg per day, as deficiency is linked to elevated CRP and systemic inflammation
- Vitamin D3: 2000–4000 IU per day if deficient, as low vitamin D levels are associated with higher CRP
- Probiotics: Multi-strain formulations (10–50 billion CFU) to support gut microbiome balance and reduce inflammatory signals
Related Biomarkers
Frequently Asked Questions
What is the difference between CRP and hs-CRP?
Standard CRP is a test used to detect significant, acute inflammation or infection, and it is typically reported in ranges above 10 mg/L. High-sensitivity CRP (hs-CRP) uses a more precise assay to detect much lower levels of the same protein, typically in the range of 0.1–10 mg/L. The hs-CRP test is preferred for cardiovascular risk assessment because it can identify the kind of subtle, chronic, low-grade inflammation linked to heart disease, even in people who feel completely healthy.
Can CRP be elevated even if I feel fine?
Yes, absolutely. One of the most important and often overlooked aspects of CRP is that it can be chronically elevated due to low-grade inflammation from lifestyle factors like poor diet, excess weight, physical inactivity, or sleep deprivation, without causing any noticeable symptoms. This is precisely why hs-CRP is so useful as a screening tool — it can signal underlying cardiovascular or metabolic risk years before a person develops any symptoms of disease.
How quickly does CRP change after starting treatment or lifestyle changes?
CRP can rise very rapidly in response to acute infection or injury, sometimes doubling every 8 hours and peaking within 48–72 hours. It also falls relatively quickly once the trigger is resolved — typically returning toward baseline within 1–2 weeks after an acute illness. For chronic, lifestyle-driven CRP elevation, improvements through diet, exercise, and weight loss can take 4–12 weeks to show measurable reductions in the bloodstream.