C-Reactive Protein (Blood) - Health Encyclopedia (2024)

Does this test have other names?


What is this test?

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. CRP is a protein made by the liver and sent into the bloodstream. Blood levels may be higher when you have inflammation or an infection. Because CRP levels often go up before you have symptoms of pain or fever and drop down as you recover, the CRP test is especially useful for tracking infections.

Because CRP is part of the immune system, your levels of it rise whenever you have inflammation in your body. But the test doesn't show where the inflammation is or what is causing it.

A high-sensitivity CRP test (hs-CRP) may be used to measure your heart disease risk even if you seem healthy. It can find much smaller changes in CRP levels than the regular CRP test.

Why do I need this test?

You may need this test if your healthcare provider thinks you have an infection. For example, it may be osteomyelitis, which involves bone. 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. CRP levels can alsorise when you have a viral infection. But they don’t go as high as during a bacterial infection.

Your healthcare provider may also order the test if they think you have an inflammatory condition or an autoimmune disease, such as rheumatoid arthritis. CRP levels are higher in people with these conditions. This test may also be used to watch flare-ups and recovery. Symptoms of rheumatoid arthritis include joint swelling and pain, morning stiffness, tiredness, weight loss, and low-grade fevers.

If you are being treated for a long-term inflammatory condition or an infection, this test may be used to see if the treatment is working.

The more specialized CRP test for heart disease risk is not covered in this article.

What other tests might I have along with this test?

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. It's not as sensitive as the CRP. But it's easy to do and gives more information. So many healthcare providers will order it at the same time.

  • Antinuclear antibody (ANA) test. The ANA test measures autoantibodies that attack your cells. This is important in diagnosing some autoimmune diseases, such as lupus.

  • Rheumatoid factor (RF). This test is done to help diagnose and monitor rheumatoid arthritis.

  • Anticyclic citrullinated peptide (anti-CCP) antibodies. This test is done to help diagnose and monitor rheumatoid arthritis.

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

The normal range for this test depends on the lab and the procedure used in the lab. 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.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore.

What might affect my test results?

A number of things may cause your CRP levels to be slightly higher than normal. These include obesity, lack of exercise, cigarette smoking, and diabetes.

Certain medicines can cause your CRP levels to be lower than normal.These include nonsteroidal anti-inflammatory drugs (NSAIDs), aspirin, and steroids.

How do I get ready for this test?

You don’t need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, and supplements you are taking. This includes medicines that don’t need a prescription and any illegal drugs you may use.

C-Reactive Protein (Blood) -  Health Encyclopedia (2024)


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.

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.

Should I be concerned if my C-reactive protein is high? ›

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.

How to lower C-reactive protein levels? ›

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.

What range of CRP is considered low-grade chronic inflammation? ›

Low levels of CRP can be measured accurately, and it is thus possible to identify individuals with low-grade inflammation (LGI), defined as CRP measurement above 3 mg/L but below 10 mg/L [2,3].

What inflammation does CRP show? ›

C-reactive protein is a hom*opentameric acute-phase inflammatory protein that exhibits elevated expression during inflammatory conditions such as rheumatoid arthritis, some cardiovascular diseases, and infection.

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.

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).

What level of CRP indicates sepsis? ›

CRP was measured in ICU-admitted patients with systemic inflammatory response syndrome and compared using a cutoff of 50 mg/L with the gold standard for diagnosing sepsis, taken as isolation of organism from a suspected source of infection or the Centers for Disease Control criteria for clinical sepsis.

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, ...

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).

What is a high sensitivity level of C-reactive protein? ›

Here are what the results mean: hs-CRP level lower than 1.0 milligrams per liter (mg/L) – low risk of CVD (heart disease) hs-CRP level of 1.0 mg/L to 3.0 mg/L – moderate risk of CVD. hs-CRP level of more than 3.0 mg/L – high risk of CVD.

What does it mean if your C-reactive protein is above 15? ›

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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