C-reactive protein (CRP) is a well known marker of inflammation. It is one of the most commonly monitored markers in COVID-19 patients.
Chronic conditions such as rheumatoid arthritis (RA) or lupus also increase levels of C-reactive protein. That's because, in response to inflammation, the liver raises CRP levels which can be detected in blood.
High levels of inflammation, seen as swelling or redness, is often due to injuries and bacterial or viral infections.
But low grade inflammation, generally associated with heart disease, diabetes, or stress, is difficult to detect.
A high-sensitivity C-reactive protein (hs-CRP) blood test has the unique ability to detect low grade inflammation. That’s something you may not be able to observe visually or by other methods.
As an inflammation marker, hs-CRP is useful in assessing the risks of coronary heart disease (CHD) and cardiovascular diseases (CVD).
The CDC (Centers for Disease Control and Prevention) and American Heart Association (AHA) say testing for hs-CRP is useful to anyone with 10 to 20% risk of heart attack in next ten years (Pearson 2003).
The American Heart Association has given CRP test a rating of Class IIA (with level of evidence B). They believe enough evidence exists to confirm its usefulness in monitoring heart health.
The test is very useful to anyone with history of heart attack. The risk of future attack in this group is relatively high.
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There are seven main modulators of cardiovascular diseases, commonly known as Framingham Risk Factors:
HDL (high-density lipoprotein cholesterol)
Total cholesterol or LDL
Diabetes, and/or body mass index (BMI).
They account for most of the excess risk for coronary heart disease (CHD).
These modulators are responsible for damage in arteries as a result of inflammation in the body. High CRP levels are indication of this inflammation and can be measured as an independent marker of heart disease (Buckley 2009).
The test is useful in motivating people to follow a healthier lifestyle. It helps also improve their compliance with medication. Therefore, anyone with known heart disease will benefit from regularly testing. It can help in controlling the disease activity or monitoring the therapy.
If levels are consistently high, experts recommend talking to your doctor about the risk of coronary heart diseases or stroke. A minimum of two tests, separated by at least two weeks, should be used to determine consistently high levels.
A summary of 23 studies and sixty-five thousand participants show low, moderate, or high risk of CVD when hs-CRP levels are:
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.
The standard hs-CRP test is a simple blood test collected in the lab.
But there is a new and easier way to test your levels. An at-home inflammation test uses just a few drops with a finger prick and doesn’t require any visits to a doctor's office or a lab. You can order the test online and receive a kit by mail. CAP and CLIA-certified labs test the sample and you receive a physician reviewed report within a few days.
Recent studies suggest Vitamin D also plays an important role in inflammation and cardiovascular diseases. Therefore, it also checks for Vitamin D levels.
The American Heart Association recommends checking cholesterol levels (HDL, LDL, and total values) regularly. High cholesterol is well known predictor of poor heart health.
Fasting is not necessary before collecting the sample. However, reviewing medication prior to testing is important 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).
C-reactive protein levels show strong correlation to cardiovascular diseases. Therefore, any life style changes that reduce the risk of heart disease may lower CRP levels. Other modulators are:
Recent injuries or illness, such as sinus problems, flu, bacterial or viral infections, can raise CRP levels.
Statins lower CRP levels (Albert 2001).
Some medications, e.g., anti-inflammatory drugs, may 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 may also affect the levels.
The hs-CRP test does not check for heart disease–it measures 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–many factors determine your risk, including lifestyle, genes, and Framingham risk factors. A cholesterol and lipids test might help in further assessing this risk.
A single test is insufficient to determine the risk as short term illness and injuries can convolute the results. That's why experts recommend a second test within about two weeks.
Most of the recommendations for improving heart health will also lower CRP levels. Some of these recommendations include:
Healthy eating habits that include more fruits and vegetables. Certain spices and herbs are historically known to reduce inflammation (e.g., turmeric).
Regular exercise and physical activity.
Weight management especially around the waist.
Quitting smoking, as it is one of the biggest modulator of heart disease.
Controlling blood pressure and blood sugar levels.
Lower stress levels through meditation, yoga, and work-life balance.
C Reactive Protein (CRP) (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)