C-Reactive Protein (CRP) Test: MedlinePlus Medical Test (2024)

What is a c-reactive (CRP) protein test?

A c-reactive protein test measures the level of c-reactive protein (CRP) in a sample of your blood. CRP is a protein that your liver makes. Normally, you have low levels of c-reactive protein in your blood. Your liver releases more CRP into your bloodstream if you have inflammation in your body. High levels of CRP may mean you have a serious health condition that causes inflammation.

Inflammation is your body's way of protecting your tissues and helping them heal from an injury, infection, or other disease. Inflammation can be acute (sudden) and temporary. This type of inflammation is usually helpful. For example, if you cut your skin, it may turn red, swell, and hurt for a few days. Those are signs of inflammation. Inflammation can also happen inside your body.

If inflammation lasts too long, it can damage healthy tissues. This is called chronic (long-term) inflammation. Chronic infections, certain autoimmune disorders, and other diseases can cause harmful chronic inflammation. Chronic inflammation can also happen if your tissues are repeatedly injured or irritated, for example from smoking or chemicals in the environment.

A CRP test can show whether you have inflammation in your body and how much. But the test can't show what's causing the inflammation or which part of your body is inflamed.

Other names: c-reactive protein, serum

What is it used for?

A CRP test may be used to help find or monitor inflammation in acute or chronic conditions, including:

Infections from bacteria or viruses
Inflammatory bowel disease, disorders of the intestines that include Crohn's disease and ulcerative colitis
Autoimmune disorders, such as lupus, rheumatoid arthritis, and vasculitis
Lung diseases, such as asthma

Your health care provider may use a CRP test to see if treatments for chronic inflammation are working or to make treatment decisions if you have sepsis. Sepsis is your body's extreme response to an infection that spreads to your blood. It's a life-threatening medical emergency.

Why do I need a CRP test?

You may need this test if you have symptoms of a bacterial infection, such as:

Fever or chills
Rapid heart rate
Rapid breathing
Nausea and vomiting

You may also need a CRP test if your provider thinks you may have a chronic condition that causes inflammation. The symptoms will depend on the condition.

What happens during a CRP test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This process usually takes less than five minutes.

Will I need to do anything to prepare for the test?

Some medicines may affect your results. So, tell your provider about any supplements or medicines that you take, including ibuprofen, aspirin, and other non-steroidal anti-inflammatory drugs (NSAIDS). Don't stop taking any prescription medicines without talking with your provider first.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

Your CRP test results tell you how much inflammation you have in your body. But your test results can't tell you what's causing the inflammation. To make a diagnosis, your provider will look at your CRP results along with the results of other tests, your symptoms, and medical history.

In general, healthy people have very low amounts of CRP in their blood. Any increases above normal mean you have inflammation in your body. But labs measure CRP levels in different ways, and they define "normal" CRP ranges differently, so it's best to ask your provider what your results mean.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a CRP test?

A CRP test is sometimes confused with a high-sensitivity-(hs) CRP test. They both measure CRP, but they are used for different conditions. An hs-CRP test measures very tiny increases in your CRP levels. It is used to estimate your risk of heart disease.

References

Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Sepsis; [reviewed 2021 Aug 17; cited 2022 Jun 8]; [about 4 screens]. Available from: https://www.cdc.gov/sepsis/what-is-sepsis.html
Cleveland Clinic: Health Library: Diagnostics & Testing [Internet]. Cleveland (OH): Cleveland Clinic; c2022.C-Reactive Protein (CRP) Test [reviewed 2022 May 17; cited 2022 Jun 8]; [about 14 screens]. Available from: https://my.clevelandclinic.org/health/diagnostics/23056-c-reactive-protein-crp-test
InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. What is an inflammation? 2010 Nov 23 [Updated 2018 Feb 22; cited 2022 Jun 8]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279298
LabCorp [Internet]. Burlington (NC): Laboratory Corporation of America® Holdings; c2022. Patient Test Information: C-Reactive Protein (CRP); [reviewed 2019; cited 2022 Jun 8]; [about 5 screens]. Available from: https://www.labcorp.com/help/patient-test-info/c-reactive-protein-crp
Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2022. C-reactive protein test; [cited 2022 Jun 3]; [about 5 screens]. Available from: https://www.mayoclinic.org/tests-procedures/c-reactive-protein-test/about/pac-20385228
Mayo Clinic: Mayo Medical Laboratories [Internet]. Mayo Foundation for Medical Education and Research; c1995–2022. Test ID: CRP: C-Reactive Protein, Serum: Clinical and Interpretive; [cited 2022 Jun 3]; [about 3 screens]. Available from: https://www.mayocliniclabs.com/test-catalog/overview/9731#Clinical-and-Interpretive
National Cancer Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; NCI Dictionary of Cancer Terms: inflammation; [cited 2022 Jun 3]; [about 3 screens]. Available from: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/inflammation
National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests; [updated 2022 Mar 24; cited 2022 Jun 3]; [about 7 screens]. Available from: https://www.nhlbi.nih.gov/health/blood-tests
Nehring SM, Goyal A, Patel BC. C Reactive Protein. [Updated 2021 Dec 28; cited 2022 Jun 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441843/
Nemours Children's Health System [Internet]. Jacksonville (FL): The Nemours Foundation; c1995–2022. Blood Test: C-Reactive Protein (CRP); [cited 2021 Sep]; [about 3 screens]. Available from: https://kidshealth.org/en/parents/test-crp.html
Quest Diagnostics [Internet]. Quest Diagnostics; c2000–2022. Test Center: C-Reactive Protein (CRP); [cited 2022 Jun 3]; [about 2 screens]. Available from: https://testdirectory.questdiagnostics.com/test/test-detail/4420/c-reactive-protein-crp?p=r&q=c%20reactive%20protein&cc=MASTER
Testing.com [Internet]. Seattle (WA): OneCare Media; c2022. Urinalysis; [modified 2021 Nov 9; cited 2022 Jun 3]; [about 9 screens]. Available from: https://www.testing.com/tests/c-reactive-protein-crp/
Testing.com [Internet]. Seattle (WA): OneCare Media; c2022. Urinalysis; [modified 2021 Nov 9; cited 2022 Jun 3]; [about 9 screens]. Available from: https://www.testing.com/glossary/#inflammation
University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2022. Health Encyclopedia: C-Reactive Protein (Blood); [cited 2022 Jun 3]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=c_reactive_protein_serum
UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2022. C-Reactive Protein (CRP) Test; [updated 2022 Jan 10; cited 2022 Jun 3]; [about 3 screens]. Available from: https://patient.uwhealth.org/healthwise/article/en-us/tu6309

FAQs

C-Reactive Protein (CRP) Test: MedlinePlus Medical Test? ›

A c-reactive protein test measures the level of c-reactive protein (CRP) in a sample of your blood. CRP is a protein that your liver makes. Normally, you have low levels of c-reactive protein in your blood. Your liver releases more CRP into your bloodstream if you have inflammation in your body.

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What is CRP C-reactive protein test? ›

What is the C-reactive protein (CRP) blood test? The C-reactive protein (CRP) test is a blood test that checks for inflammation in your body. CRP is a protein that is made in your liver and released into your bloodstream. Levels of CRP start to increase very soon after any inflammation or infection affects your body.

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What level of CRP is concerning? ›

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.

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What is the most common cause of high CRP? ›

Lifestyle: People who smoke, have obesity, or do little exercise may have higher-than-normal CRP levels. Minor injuries or infection: These conditions may temporarily raise CRP levels and conceal other potential conditions, such as diabetes or IBD.

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

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What happens when CRP is high? ›

Your liver releases more CRP into your bloodstream if you have inflammation in your body. High levels of CRP may mean you have a serious health condition that causes inflammation. Inflammation is your body's way of protecting your tissues and helping them heal from an injury, infection, or other disease.

Is a positive CRP good or bad? ›

Generally, a CRP level under 10 milligrams per liter (mg/L) is considered normal. If the level of CRP in your blood is higher than that, it may mean your body is having an inflammatory reaction to something. More tests will be needed to figure out what's causing the inflammation.

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What autoimmune disease causes high CRP? ›

That reaction causes inflammation, so high CRP levels tick one box for an autoimmune diagnosis. But that's just the tip of the iceberg. “The CRP will go up pretty much from any inflammation, which can be from infection or an inflammatory condition like rheumatoid arthritis, or even atherosclerosis,” says Dr. Kaplan.

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What is a critical level of 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).

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What is the danger level of CRP? ›

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.

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What cancers can CRP detect? ›

CRP is considered to be related to cancer progression, and increased serum levels of CRP have been detected in many carcinomas, such as colorectal (8), lung (9) and gastric cancer (10-12).

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What should I avoid if my CRP is high? ›

Limiting or avoiding inflammatory foods like refined carbohydrates, fried foods, red meat and processed meat can help reduce CRP. Instead, focus on eating more anti-inflammatory foods like leafy greens, nuts, fatty fish and whole grains.

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What infections are associated with high CRP? ›

Substantially raised CRP values are usually found in pneumonia,³^-⁶ and a high CRP value has been shown to be a strong predictor for this disease in general practice. However, raised CRP values may also be found in uncomplicated viral respiratory infections, particularly those caused by influenza virus and adenovirus.

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What medication is used to treat CRP? ›

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, ...

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Can high CRP cause joint pain? ›

This triggers inflammation, which causes joint pain, swelling, and stiffness. Blood tests can help confirm a diagnosis of RA. People with the disease often have elevated levels of certain proteins, including C-reactive protein (CRP), in their blood.

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What happens if high CRP is left untreated? ›

When CRP remains high, it is an indication of chronic inflammation. Elevated CRP is a risk factor for many chronic inflammation-related disorders, including cardiovascular disease, cancer, diabetes, obesity, and more.

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What should I do if my C-reactive protein is positive? ›

What's the Treatment for High C-Reactive Protein?

Eat a heart-healthy diet.
Get your high cholesterol down.
Keep your weight where it should be.
Exercise regularly.
If you have diabetes or high blood pressure, manage it.
If you smoke or use tobacco in another way, quit.
If you drink alcohol, do so responsibly.

Feb 19, 2024

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How to bring CRP levels down? ›

Limiting or avoiding inflammatory foods like refined carbohydrates, fried foods, red meat and processed meat can help reduce CRP. Instead, focus on eating more anti-inflammatory foods like leafy greens, nuts, fatty fish and whole grains.

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What happens if C-reactive protein is low? ›

What does a low CRP level mean? Since the normal CRP level is generally less than 0.9 mg/dL, there's no such thing as a lower than normal CRP level. If you previously had a high CRP result and now have a lower result, it likely means your inflammation is decreasing and/or your treatment for the inflammation is working.

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What does it mean when your inflammatory markers are elevated? ›

What does a raised inflammatory marker mean? Medical decisions will not be made solely on the results of an inflammatory marker test. Abnormal results suggest inflammation, but don't identify the cause: it might be as simple as a viral infection, or as serious as cancer.

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