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.

If you've already been diagnosed with an infection or a chronic disease that causes inflammation, you may need this test to monitor your condition and treatment. CRP levels rise and fall depending on how much inflammation is in your body. If your CRP levels fall, it's a sign that your treatment for inflammation is working or you're healing on your own.

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

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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/
  10. 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
  11. 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
  12. 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/
  13. 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
  14. 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
  15. 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
C-Reactive Protein (CRP) Test: MedlinePlus Medical Test (2024)

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.

What does C-reactive protein CRP indicate? ›

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.

What is an acceptable CRP level? ›

Interpretation of CRP levels:

Less than 0.3 mg/dL: Normal (level seen in most healthy adults). 0.3 to 1.0 mg/dL: Normal or minor elevation (can be seen in obesity, pregnancy, depression, diabetes, common cold, gingivitis, periodontitis, sedentary lifestyle, cigarette smoking, and genetic polymorphisms).

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.

What level of CRP indicates arthritis? ›

Normal C-reactive protein (CRP) levels
C-reactive protein level (in milligrams per liter of blood) in adultsWhat it means
10.0–100.0moderately elevated, which signifies infection or an inflammatory condition such as rheumatoid arthritis (RA), Crohn's disease, or lupus
4 more rows

What infections cause 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.

What happens if C-reactive protein is positive? ›

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.

What autoimmune disease causes high C-reactive protein? ›

A 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.

What is a critical level of CRP? ›

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 safe CRP level? ›

Normal Range of CRP Level in the Blood

A normal range falls between 0 to 3 milligrams per liter (mg/L) of blood. Elevated levels may signal an underlying health concern. While there is no such thing as a “low” CRP level, the normal range is generally less than 0.9 mg/dL.

What cancers cause high CRP? ›

Elevated CRP levels have been found to be associated with several cancers, including breast, lung, gastric, and colorectal cancer, hepatocellular carcinoma, and renal carcinoma (Roxburgh and McMillan, 2010; Wu et al., 2011).

When should I worry about CRP? ›

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.

What CRP level needs antibiotics? ›

◦ In cases of high CRP values (i.e.,: >75 mg/L) it is strongly suggested to start treatment with antibiotics, due to a high risk of a non-self-limiting infection, or to refer to a hospital (10).

What is a normal CRP level for inflammation? ›

C-Reactive Protein Test Result
CRP LEVELCLASSIFICATION
Less than 0.3 mg/dL (milligrams per deciliter)Normal
0.3 to 1.0 mg/dLNormal or minor elevation
1.0 to 10.0 mg/dLModerate elevation
More than 10.0 mg/dLMarked elevation
1 more row
Feb 19, 2024

How to bring CRP levels down? ›

Eating a heart-healthy diet (e.g., eating plenty of anti-inflammatory foods such as salmon, tuna, and plant-based proteins, avoiding processed meat, consuming omega-3 fatty acids or monounsaturated fatty acids, and including more fresh fruits and vegetables)10. Reducing stress.

What is CRP for joint infection? ›

Serum C-reactive protein (CRP) is an important test in the initial diagnosis of prosthetic joint infection (PJI). There is no widely accepted algorithm for the resolution of PJI. Surgeons have traditionally used CRP to determine if the infection has resolved.

When should I be worried about high C-reactive protein? ›

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.

How do you treat high C-reactive protein? ›

There's no doubt that the very best way to lower CRP is through exercise, weight loss, and dietary control; of course, those are all proven already to lower vascular risk. There is a paper that came out in February comparing the Atkins diet, the Zone diet, the Weight Watchers diet, and the Ornish diet.

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

Where patients tested positive for raised inflammatory markers, 15 per cent were caused by disease such as an infection, autoimmune condition or cancer. In the remaining 85 per cent of patients with raised inflammatory markers, no relevant disease could be found. These results are known as 'false positives'.

What are the five inflammatory markers? ›

The most frequently used inflammatory markers include acute-phase proteins, essentially CRP, serum amyloid A, fibrinogen and procalcitonin, and cytokines, predominantly TNFα, interleukins 1β, 6, 8, 10 and 12 and their receptors and IFNγ.

Top Articles
Latest Posts
Recommended Articles
Article information

Author: Greg Kuvalis

Last Updated:

Views: 5415

Rating: 4.4 / 5 (55 voted)

Reviews: 94% of readers found this page helpful

Author information

Name: Greg Kuvalis

Birthday: 1996-12-20

Address: 53157 Trantow Inlet, Townemouth, FL 92564-0267

Phone: +68218650356656

Job: IT Representative

Hobby: Knitting, Amateur radio, Skiing, Running, Mountain biking, Slacklining, Electronics

Introduction: My name is Greg Kuvalis, I am a witty, spotless, beautiful, charming, delightful, thankful, beautiful person who loves writing and wants to share my knowledge and understanding with you.