Anil Kumar, PhD | Last updated: Nov 28, 2018
C-reactive protein (CRP) is a commonly used marker of inflammation.
The liver raises CRP levels in response to inflammation in the body. High levels of inflammation can be caused by injuries, bacterial or viral infections. Chronic conditions such as rheumatoid arthritis (RA) or lupus also increase C-reactive protein levels.
A high-sensitivity C-reactive protein (hs-CRP) test can help assess low level of inflammation. That’s something you may not be able to observe visually or by other methods.
As an inflammation marker, hs-CRP is also an indicator of risks of coronary heart disease (CHD) and cardiovascular diseases (CVD). The American Heart Association (AHA) and Centers for Disease Control and Prevention (CDC) say the test is useful for anyone with a 10-20% risk of heart attack in next ten years (Pearson 2003).
The American Heart Association (AHA) has given CRP test a rating of Class IIA (with level of evidence B). That means they believe enough evidence exists to confirm the usefulness of such a test for monitoring heart health.
For someone with a previous heart attack the test can be specifically useful. The risk of future attack in this group is relatively high.
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There are seven main modulators of cardiovascular diseases, called Framingham Risk Factors: age, gender, blood pressure, HDL (high-density lipoprotein cholesterol), total cholesterol or LDL, smoking, diabetes, and body mass index (BMI). These account for most of the excess risk for coronary heart disease (CHD).
These factors cause damage to the arteries resulting in inflammation in the body. High CRP levels are indication of this inflammation and act as an independent marker of heart disease (Buckley 2009).
Why test for hs-CRP or inflammation? The test might be useful in motivating people to make better lifestyle decisions. It may also improve their compliance with medication to improve overall health. Those with known heart disease might benefit as well. Regularly testing the levels will allow measuring their efforts at controlling the disease activity or monitoring the therapy.
If levels are consistently high, experts recommend talking to your doctor to assess the risk of coronary heart diseases or stroke. Minimum of two tests, ideally separated by at least two weeks, should be used to determine consistently high levels.
What is a good CRP level?
Based on the summary of 23 studies and over sixty-one thousand participants, hs-CRP levels show low, moderate, or high risk of cardiovascular disease as following:
- Below 1 mg/L: low risk of heart disease
- 1 – 3 mg/L: moderate risk of heart disease
- 3 – 10 mg/L: high risk of heart disease
- Over 10 mg/L: can not indicate the risk of heart disease due to inflammation caused by other reasons
How to test for CRP levels and inflammation?
The standard hs-CRP test is basically a simple blood test that uses a sample collected in the lab.
But there is a new and easier way to test your levels. An at-home inflammation test uses a small sample that can be collected at home and doesn’t require you to visit a doctor or lab. You can order the test online and receive the At-Home Inflammation and Vitamin D test kit by mail. A CLIA-certified lab will test the sample and send you a physician reviewed report in few days.
Recent studies suggest Vitamin D also plays a role in inflammation and cardiovascular diseases. Therefore, the test also checks for Vitamin D levels to ensure your levels are not affected by low Vitamin D levels.
The American Heart Association recommends checking your cholesterol levels (HDL, LDL, and total values) regularly. High cholesterol levels are well known predictor of poor heart health.
Fasting is not necessary before collecting a sample. However, medication should be reviewed during the test as certain drugs are known to artificially affect the levels.
Because short term health conditions such as illness or injury can raise CRP levels, experts recommend testing two samples about two weeks apart (Pearson 2003).
What can affect CRP levels?
C-reactive protein levels show strong correlation to most risk factors of cardiovascular diseases. Therefore, any life style changes that reduce the risk of heart disease may lower CRP levels. There are other modulators of CRP levels:
- Recent injuries or illness such as sinus, flu, bacterial or viral infections can raise CRP levels
- Statins show reduction in C-reactive protein levels (Albert 2001)
- Some medications, e.g., anti-inflammatory drugs affect the results
- Magnesium supplements can artificially lower CRP levels
- Chronic conditions such as arthritis, diabetes, lupus, or auto-immune diseases can keep CRP chronically high and make it difficult to determine any correlation with heart disease
- Pregnancy and birth control pills are also affect CRP levels
What the hs-CRP test doesn’t do?
- The hs-CRP test does not check for heart disease–it checks for inflammation in the body that might correlate to a heart disease
- The test is not for everyone–CDC and American Heart Association recommend it for those with a 10-20% risk of heart disease in next 10 years
- An hs-CRP test can not tell where the inflammation is happening since it is a non-specific marker
- A low value might not mean low risk of heart disease–so many other factors determine your risk, including lifestyle and Framingham risk factors (weight, HDL, diabetes, smoking, age, gender, blood pressure, etc.); a cholesterol and lipids test might help in further assessing this risk
- A single test is insufficient to determine the risk of heart disease as short term illness and injuries can convolute the results; experts recommend a second test within about two weeks
How to lower CRP levels?
As an indicator of inflammation, C-reactive protein is an independent marker of heart disease. Most of the recommendations for improving heart health therefore will also lower CRP levels. Some of these recommendations include:
- Healthy eating habits that include more fruits and vegetables (e.g., with certain spices and herbs historically known to reduce inflammation)
- Regular exercise and physical activity
- Weight management especially around the waist
- Avoid smoking which is one of the biggest modulator of heart disease
- Controlling your blood pressure and blood sugar levels
- Lower stress levels through meditation, yoga, and work-life balance
- C Reactive Protein (CRP) by Nehring and Patel
- C-Reactive Protein Test by Mayo Clinic
- C-Reactive Protein as a Risk Factor for Coronary Heart Disease: A Systematic Review and Meta-analyses for the U.S. Preventive Services Task Force by Buckley et al. Annals of Internal Medicine 151 p.483-495 (2009)
- C-reactive protein was a moderate predictor of coronary heart disease by Danesh et al., N Engl J Med and Etiology 350 p.1387-1397 (2004)
- Markers of Inflammation and Cardiovascular Disease by Pearson et al., Circulation 107 p.499–511 (2003)
- High Attributable Risk of Elevated C-Reactive Protein Level to Conventional Coronary Heart Disease Risk Factors by Miller et al., JAMA Arch Intern Med 165 (18), p. 2063-2068 (2005)
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