Overview
C-reactive protein (CRP) is a protein made by the liver. The level of CRP increases when there's inflammation in the body. A simple blood test can check your C-reactive protein level.
A high-sensitivity C-reactive protein (hs-CRP) test is more sensitive than a standard C-reactive protein test. That means the high-sensitivity test can find smaller increases in C-reactive protein than a standard test can.
The hs-CRP test can help show the risk of getting coronary artery disease. In coronary artery disease, the arteries of the heart narrow. Narrowed arteries can lead to a heart attack.
Why it's done
Your health care provider might order a C-reactive protein test to:
- Check for infection.
- Help diagnose a chronic inflammatory disease, such as rheumatoid arthritis or lupus.
- Learn your risk of heart disease.
- Learn your the risk of a second heart attack.
A note about CRP tests for heart disease
A high level of hs-CRP in the blood has been linked to an increased risk of heart attacks. Also, people who have had a heart attack are more likely to have another heart attack if they have a high hs-CRP level. But their risk goes down when their hs-CRP level is in the typical range.
An hs-CRP test isn't for everyone. The test doesn't show the cause of inflammation. So it's possible to have a high hs-CRP level without it affecting the heart.
An hs-CRP test may be most useful for people who have a 10% to 20% chance of having a heart attack within the next 10 years. This is known as intermediate risk. A health care provider can determine your risk using tests that look at your lifestyle choices, family history and overall health.
More Information
- Adult Still disease
- Giant cell arteritis
- Juvenile idiopathic arthritis
- Polymyalgia rheumatica
- Takayasu's arteritis
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How you prepare
Hard exercise, such as intense weight training or a long run, can cause a sudden jump in the C-reactive protein level. Your health care provider might ask you to avoid such activities before the test.
Some medicines can affect CRP level. Tell your care provider about the medicines you take, including those you bought without a prescription.
If your blood sample will be used for other tests, you may need to avoid food or drink for a period before the test. For example, if you're having an hs-CRP test to check for heart disease, you might have a cholesterol test, which requires fasting, at the same time.
Your health care provider tells you how to prepare for your test.
What you can expect
To take a sample of your blood, a health care provider places a needle into a vein in your arm, usually at the bend of the elbow. The blood sample goes to a lab for analysis. You can return to your usual activities right away.
Results
It can take a few days to get results. Your health care provider can explain what the test results mean.
C-reactive protein is measured in milligrams per liter (mg/L). Results equal to or greater than 8 mg/L or 10 mg/L are considered high. Range values vary depending on the lab doing the test.
A high test result is a sign of inflammation. It may be due to serious infection, injury or chronic disease. Your health care provider may recommend other tests to determine the cause.
Results for an hs-CRP test are usually given as follows:
- Lower risk of heart disease: Less than 2.0 mg/L
- Higher risk of heart disease: Equal to or greater than 2.0 mg/L
A person's CRP levels vary over time. A coronary artery disease risk assessment should be based on the average of two hs-CRP tests. It's best if they're taken two weeks apart. Values above 2.0 mg/L may mean an increased risk of heart attacks or risk of a repeat heart attack.
Hs-CRP level is only one risk factor for coronary artery disease. Having a high hs-CRP level doesn't always mean a higher risk of developing heart disease. Other tests results can help determine the risk.
Talk to your health care provider about your risk factors for heart disease and ways to try to prevent it. Lifestyle changes or medicines might help lower the risk of a heart attack.
Dec. 22, 2022
FAQs
Although there are limitations to what the CRP test can reveal, it is a relatively reliable way to measure inflammation. The higher the CRP levels, the greater amount of inflammation in the body.
What level of C-reactive protein is concerning? ›
You are at low risk of developing cardiovascular disease if your hs-CRP level is lower than 1.0 mg/L. You are at average risk of developing cardiovascular disease if your levels are between 1.0 mg/L and 3.0 mg/L. You are at high risk for cardiovascular disease if your hs-CRP level is higher than 3.0 mg/L.
What is a critical result for CRP? ›
Interpretation of CRP levels:
More than 10.0 mg/dL: Marked elevation (Acute bacterial infections, viral infections, systemic vasculitis, major trauma). More than 50.0 mg/dL: Severe elevation (Acute bacterial infections).
What is an alarming CRP? ›
A CRP test result of more than 50 mg/dL is generally considered severe elevation. Results over 50 mg/L are associated with acute bacterial infections about 90% of the time.
Is CRP a reliable marker? ›
Inflammation causes a rapid increase in CRP levels, which are often used clinically as reliable measures of disease activity and response to treatment in RA [2, 3, 5].
Is C-reactive protein reliable? ›
Increased C-reactive protein (CRP) levels are associated with various diseases such as cardiovascular diseases (CVDs), periodontal diseases, and other inflammatory diseases and can be an effective biomarker for predicting future risks of periodontal diseases.
What level of CRP indicates arthritis? ›
Normal C-reactive protein (CRP) levels
| C-reactive protein level (in milligrams per liter of blood) in adults | What it means |
|---|
| 10.0–100.0 | moderately elevated, which signifies infection or an inflammatory condition such as rheumatoid arthritis (RA), Crohn's disease, or lupus |
4 more rowsA wide variety of inflammatory conditions can cause elevated CRP levels, including :
- autoimmune conditions, including rheumatoid arthritis (RA), lupus, and certain types of inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis.
- pericarditis, which is inflammation of the lining of the heart.
Additionally, elevated CRP levels are associated with poor survival in many malignant tumors, such as soft tissue sarcoma, prostate cancer, breast cancer, renal cell carcinoma, colorectal cancer, non-small-cell lung cancer, malignant lymphoma, and pancreatic cancer (10, 13-20).
What is a risky CRP level? ›
C-Reactive Protein Test Result
| CRP LEVEL | CLASSIFICATION |
|---|
| 0.3 to 1.0 mg/dL | Normal or minor elevation |
| 1.0 to 10.0 mg/dL | Moderate elevation |
| More than 10.0 mg/dL | Marked elevation |
| More than 50.0 mg/dL | Severe elevation |
1 more rowFeb 19, 2024
Cyclooxygenase inhibitors (aspirin, rofecoxib, celecoxib), platelet aggregation inhibitors (clopidogrel, abciximab), lipid lowering agents (statins, ezetimibe, fenofibrate, niacin, diets), beta-adrenoreceptor antagonists and antioxidants (vitamin E), as well as angiotensin converting enzyme (ACE) inhibitors (ramipril, ...
What tests should be done if CRP is high? ›
Because the CRP test tells you only if you have inflammation and doesn't pinpoint what is causing it, your healthcare provider will likely order more tests. These may include: Erythrocyte sedimentation rate (ESR) test. Like the CRP, this test measures inflammation.
What is a bad CRP number? ›
In most cases, a CRP level of 50 mg/L or more indicates the existence of a bacterial infection in your body.
When should I worry about my CRP level? ›
CRP levels can vary widely depending on the underlying condition causing inflammation. Generally, a CRP level of less than 10 mg/L is considered normal. CRP levels between 10 and 100 mg/L indicate mild to moderate inflammation, while levels above 100 mg/L indicate severe inflammation.
What CRP level needs antibiotics? ›
The normal serum concentration of CRP is usually <10 mg/L but, in severe bacterial infections, it can rise as high as 500 mg/L.5 In the literature, various cut-off points have been proposed to distinguish between viral and bacterial infections, but there appears to be a consensus that a CRP value of <40 mg/L is ...
What are the limitations of CRP test? ›
Limitations of the CRP Test
A high CRP level does not automatically confirm the presence of a specific condition or infection. Instead, it only shows there's inflammation in the body, which could be due to many causes.
Is CRP test effective? ›
And while CRP tests are very effective in detecting inflammation in your body, additional tests may be needed to confirm the exact causes of this issue.
What illnesses does C-reactive protein show? ›
The C-reactive protein (CRP) test is used to find inflammation in your body. Inflammation could be caused by different types of conditions, such as an infection or autoimmune disorders like rheumatoid arthritis or inflammatory bowel disease. This test measures the amount of CRP in your blood.
What is the best test to check for heart problems? ›
An echocardiogram is a common test. It gives a picture of your heart using ultrasound, a type of X-ray. It uses a probe either on your chest or down your oesophagus (throat). It helps your doctor check if there are any problems with your heart's valves and chambers, and see how strongly your heart pumps blood.
