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

Table of Contents

What is a c-reactive (CRP) protein test? What is it used for? Why do I need a CRP test? What happens during a CRP test? Will I need to do anything to prepare for the test? Are there any risks to the test? What do the results mean? Is there anything else I need to know about a CRP test? References FAQs References

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

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

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

FAQs

What is an alarming level of 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.

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What is an acceptable CRP level? ›

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).

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How important is C-reactive protein test? ›

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 ...

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What is the most appropriate diagnostic test for CRP? ›

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.

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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 rows

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What is a safe 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.

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What is a critical level of CRP? ›

It is unclear if a minor rise of 0.3 to 1 mg/dL in CRP levels is a cause for concern. The hs-CRP is more precise and may be used to further understand these results. CRP levels from 1 mg/dL to 10 mg/dL are thought to be a moderate increase. CRP Levels greater than 10 mg/dL are considered a marked increase.

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What is the most common cause of high CRP? ›

Significantly elevated CRP levels tend to occur with severe infections, such as bacterial or fungal infections. Bacterial infection is responsible for about 90% of the cases involving CRP levels higher than 50 mg/l.

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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 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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Is CRP related to cholesterol? ›

However, your CRP can't tell us everything. It's important to look at it in relation to your cholesterol, specifically low-density lipoprotein (LDL). LDL is considered the bad cholesterol because it collects in your arteries and can cause blockages. Your CRP modifies your LDL level.

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

What should I do if my C-reactive protein is positive? If by "positive" you mean it's at a high level, talk to your doctor. They may recommend lifestyle changes (diet and exercise) or taking a statin.

How accurate is a CRP test? ›

Most adults with little or no inflammation have CRP levels less than 0.3 mg/dL. In some rare cases, CRP levels read low in people with inflammatory conditions like lupus or rheumatoid arthritis. Still, CRP tests are quite accurate in showing inflammation.

What are the two types of CRP tests? ›

The standard test measures high levels of the protein to find different diseases that cause inflammation. The hs-CRP test measures low levels and focuses on the risk of heart disease and stroke.

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What is the CRP normal range? ›

Normal Range of CRP Levels

S.No.	CRP Level	Inference
1.	< 3 mg/L	Normal
2.	3 mg/L - 10 mg/L	Normal or minor elevation
3.	10 mg/L - 100 mg/L	Moderate elevation
4.	100 mg/L - 500 mg/L	Marked elevation

1 more row

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What level of CRP indicates sepsis? ›

Initial CRP levels did not differ among patients with sepsis or septic shock (median CRP level day 1 in sepsis: 150 (97–225) mg/l; septic shock: 127 (79–219) mg/l; p = 0.092). However, in the presence of septic shock, CRP was shown to increase until day 10 of ICU hospitalization (median 179 (66–225) mg/l).

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What is the highest CRP can go? ›

Normal Range of CRP Levels

S.No.	CRP Level	Inference
1.	< 3 mg/L	Normal
2.	3 mg/L - 10 mg/L	Normal or minor elevation
3.	10 mg/L - 100 mg/L	Moderate elevation
4.	100 mg/L - 500 mg/L	Marked elevation

1 more row

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Is 20 a high CRP level? ›

The patients with the very highest levels of hsCRP —5 to 10, 10 to 20, or even greater than 20 mg/L—are, in fact, at the very highest risk. These are not false positives. These data help to explain why those with periodontal disease, arthritis, and other systemic inflammatory disorders all have higher vascular risk.

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