C-reactive protein (2024)

Acute phase reactants - CRP

C-reactive protein (CRP) is produced by the liver. The level of CRP rises when there is inflammation in the body. It is one of a group of proteins, called acute phase reactants that go up in response to inflammation. The levels of acute phase reactants increase in response to certain inflammatory proteins called cytokines. These proteins are produced by white blood cells during inflammation.

This article discusses the blood test done to measure the amount of CRP in your blood.

How the Test is Performed

A blood sample is needed. This is most often taken from a vein. The procedure is called a venipuncture.

How to Prepare for the Test

No special steps are needed to prepare for this test.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others may feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the Test is Performed

The CRP test is a general test to check for inflammation in the body. It is not a specific test. This means it can reveal that you have inflammation somewhere in your body, but it cannot pinpoint the exact location or reason. The CRP test is often done with the ESR (erythrocyte or sedimentation rate) test which also looks for inflammation.

You may have this test to:

Check for flare-ups of inflammatory diseases such as rheumatoid arthritis, lupus, or vasculitis.
Determine if anti-inflammatory medicine is working to treat a disease or condition.

A more sensitive CRP test, called a high-sensitivity C-reactive protein (hs-CRP) assay, is available to determine a person's risk for heart disease.

Normal Results

Normal CRP values vary from lab to lab. The levels often increase slightly with age, female sex and in African Americans. The majority of healthy adults have levels less than 0.3 mg/dL.

However, a low CRP level does not always mean that there is no inflammation present. Levels of CRP may not be increased in people with rheumatoid arthritis and lupus. The reason for this is unknown.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your health care provider about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

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.

A positive test means you have inflammation in the body. The cause of a high CRP cannot always be determined. Some include:

Cancer
Heart attack
Infection
Inflammatory bowel disease (IBD)
Rheumatoid arthritis, lupus, and related diseases
Rheumatic fever

According to the American Heart Association, results of the hs-CRP can be interpreted as follows:

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.

Note: Positive CRP results also occur during the last half of pregnancy or with the use of birth control pills (oral contraceptives).

Risks

Risks associated with having blood drawn are slight, but may include:

Excessive bleeding
Fainting or feeling lightheaded
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)

References

Dietzen DJ, Willrich MAV. Amino acids, peptides, and proteins. In: Rifai N, Chiu RWK, Young I, Burnham CD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. St Louis, MO: Elsevier; 2023:chap 31.

Haberman R, Fors Nieves CE, Cronstein BN, Saxena A. Acute phase reactants. In: Firestein GS, Budd RC, Gabriel SE, Koretzky GA, McInnes IB, O'Dell JR, eds. Firestein & Kelley's Textbook of Rheumatology. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 60.

Mora S, Libby P, Ridker PM. Primary prevention of cardiovascular disease. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 25.

Version Info

Last reviewed on: 1/25/2023

Reviewed by: Neil J. Gonter, MD, Assistant Professor of Medicine, Columbia University, NY and private practice specializing in Rheumatology at Rheumatology Associates of North Jersey, Teaneck, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

FAQs

What does it mean if CRP C is high? ›

A high CRP is more than 10mg/L. This shows that there is inflammation somewhere in your body. Other tests might be necessary to find out where or which specific illness or infection is causing the inflammation. If you are being treated for an infection or inflammation, your CRP levels should decrease.

Know More ›

What level of C-reactive protein is concerning? ›

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.

See Details ›

What is an alarming CRP? ›

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.

Discover More Details ›

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.

Get More Info ›

Should I be concerned if my CRP is high? ›

If your CRP test results reveal that you have high levels of CRP, it doesn't necessarily mean that you have a medical condition that needs treatment, especially if they're only slightly elevated. Several factors, such as smoking, recent injury and certain health conditions, can raise your CRP levels.

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.

Tell Me More ›

What cancers have 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).

Know More ›

Is CRP a tumor marker? ›

Elevated CRP levels (> 10 μg/ml) are associated with active, advanced cancer disease.

Get More Info ›

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.

Keep Reading ›

What medications affect C-reactive protein? ›

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, ...

Know More ›

What foods should you avoid if you have high CRP? ›

Avoid Foods That Cause Inflammation: Processed meals, sugary snacks, and excessive consumption of red meat can all contribute to inflammation. Limiting these foods in your diet can help lower CRP levels.

View Details ›

Can dehydration cause high CRP levels? ›

This is particularly concerning as high CRP levels, potentially exacerbated by factors like dehydration and certain dietary habits, can indicate a dangerous level of inflammation in the body.

Know More ›

What are the symptoms of C reactive protein? ›

Or it may be a potentially life-threatening condition called sepsis or blood poisoning. Symptoms of sepsis may include fever and chills, headache, pain, nausea, vomiting, confusion, rash, and shortness of breath. The level of CRP in your blood goes up within a few hours of a serious infection.

View Details ›

What CRP level indicates Crohn's disease? ›

Conclusion: CRP elevation in Inflammatory Bowel Disease is associated with active disease determined endoscopically, histologically, or radiographically. In both CD and UC, a CRP > 2.0 mg/dL predicts findings of active ileal disease at ileocolonoscopy.

Know More ›

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.

Show Me More ›

What does C-reactive protein cardiac mean? ›

Your level of C-reactive protein can be an indicator of how at risk you are for developing cardiovascular problems. This is because the development of atherosclerosis (laying down of cholesterol inside the blood vessel walls) is associated with inflammation within the vessel walls.