What C-Reactive Protein (CRP) Levels Can Tell You About RA (2024)

Doctors can use your C-reactive protein (CRP) levels to help diagnose rheumatoid arthritis and see how well your treatment plan is working. Levels typically rise if you have inflammation or certain health conditions.

CRP is a protein that’s produced by your liver in response to cytokines, primarily IL-6, which are secreted by immune system cells. It can be found in your blood.

The levels of CRP in your blood will rise when you have an infection or major tissue injury. CRP levels in your blood also rise in response to inflammation. High CRP levels will fall when the underlying trigger is under control.

The autoimmune disease rheumatoid arthritis (RA) causes a lot of inflammation in addition to symptoms such as swollen and painful joints.

Keep reading to learn how CRP levels can be used to aid in the diagnosis and treatment of RA.

Your CRP levels should be within the normal range if you don’t have any infections or chronic inflammatory conditions such as RA.

CRP is usually measured in milligrams of CRP per liter of blood (mg/L). Normal CRP levels are typically below 3.0 mg/L. Keep in mind that the normal reference range often varies between labs.

C-reactive protein level (in milligrams per liter of blood) in adultsWhat it means
Below 3.0normal
3.0–10.0slightly elevated, which may signify a variety of conditions such as pregnancy, the common cold, or gingivitis
10.0–100.0moderately elevated, which signifies infection or an inflammatory condition such as rheumatoid arthritis (RA), Crohn’s disease, or lupus
100.0–500.0elevated, which signifies infection, inflammation of the blood vessels, or major trauma
500.0 and aboveseverely elevated, which signifies severe bacterial infection

A high-sensitivity CRP (hsCRP) test can detect levels below 10.0 mg/L. This kind of test is performed primarily to determine a person’s risk for heart disease.

hsCRP levels (in milligrams per liter of blood) in adultsWhat it means for heart disease risk
Below 1.0low risk
1.0–3.0moderate risk
3.0–10.0high risk

Any CRP level above 100 mg/L is considered elevated and may be dangerous depending on different factors, including your medical history and the underlying cause of the elevation.

Research from 2017 found that high CRP levels were associated with many diagnoses, including rheumatologic diseases.

However, the most common diagnosis was infection. CRP levels above 500 mg/L are associated with a high rate of bacterial infection.

If your CRP levels are high, you will likely need to see a healthcare professional for a diagnosis and the next steps. It is important to address high CRP levels quickly to determine the cause of inflammation and treat the root condition.

No single test can confirm that you have RA. However, measuring levels of CRP in your blood can be part of a comprehensive diagnosis. A doctor can use your CRP levels to track the degree of inflammation over time.

If you’re getting tested for RA, the doctor will likely order a standard CRP test rather than an hsCRP test.

To confirm a diagnosis of RA, the doctor will:

  • analyze results from other lab tests, such as the rheumatoid factor antibody test and cyclic citrullinated peptide (CCP) antibody test
  • assess levels of morning stiffness and the amount of swelling and pain in your joints
  • document the duration of your symptoms
  • examine X-rays of the hands and feet to check for erosions or bone damage

All you need to do for the CRP test is give a blood sample. Once your blood is drawn, it will go to a lab for testing. Your doctor will tell you the results, or you may be able to check them online.

There’s almost no risk associated with having blood drawn for the CRP test. However, reactions such as minor bruising or soreness are possible with any blood draw.

Once your doctor confirms an RA diagnosis, they may order occasional CRP tests. Your CRP levels are useful in indicating how well your treatments are working.

For instance, if you try a new medication, your doctor may test your CRP levels a few weeks after you start it.

If your levels have dropped, the medication is probably helping. If your CRP levels rise, your doctor will know that you’re having a flare-up. You may need to adjust your medications or try a new treatment.

Measuring CRP levels is not a perfect method for diagnosing RA or determining the effectiveness of treatment. This is because CRP is not specific to RA. Elevated levels of CRP can indicate any infection or a different inflammatory condition.

On the other hand, some people with RA may have normal CRP levels. An older study published in 2009 looked at databases of patients living with RA in Finland (Jyväskylä), and the United States (Nashville, Tennessee) over a period of 25 years.

Results showed that 44% of the patients in Finland and 58% of the patients in the United States had normal CRP test results at presentation.

RA can affect anyone at any age, although it’s more common in women and often first appears in middle age.

If you have symptoms of the condition, such as joint pain, joint swelling, or nodules, speak with a doctor. They can use a variety of tests, including a CRP test, to confirm a diagnosis.

If it turns out that you have RA, your doctor can help you get started on a treatment plan that helps you manage your symptoms and prevent joint damage. Treatment may involve a combination of medications and natural remedies.

What C-Reactive Protein (CRP) Levels Can Tell You About RA (2024)


What C-Reactive Protein (CRP) Levels Can Tell You About RA? ›

CRP levels are often persistently elevated in patients with RA, with levels of >20 mg/L frequently reported at baseline in randomized clinical trials (RCTs) of drugs to treat RA [35].

What level of CRP indicates RA? ›

RA causes inflammation. In response, the body releases CRP into the bloodstream. Doctors measure CRP levels as part of the diagnosis and management of RA. While many factors influence a person's CRP levels, and there is no definitive normal range, CRP levels above 10 mg/l suggest substantial inflammation.

What level of C reactive protein is concerning? ›

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 an alarming level of CRP? ›

A CRP test result of more than 10 mg/dL is generally considered a marked elevation. This result may indicate any of the following conditions: Acute bacterial infections. Viral infections.

What are the inflammation markers for rheumatoid arthritis? ›

People with rheumatoid arthritis often have an elevated erythrocyte sedimentation rate (ESR, also known as sed rate) or C-reactive protein (CRP) level, which may indicate the presence of an inflammatory process in the body.

What lab values indicate RA? ›

The normal level of anti-CCP is less than 20 Units. (At Hospital for Special Surgery, anti-CCP is reported in Units. Some labs report this same result using a different measurement notation, that is, as less than 20 EU/ml.) A level above 20 suggests the possibility of RA.

How high is CRP in autoimmune disease? ›

1.0 to 10.0 mg/dL: Moderate elevation (Systemic inflammation such as RA, SLE, or other autoimmune diseases, malignancies, myocardial infarction, pancreatitis, bronchitis). More than 10.0 mg/dL: Marked elevation (Acute bacterial infections, viral infections, systemic vasculitis, major trauma).

What kind of inflammation causes high CRP? ›

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.
  • pericarditis, which is inflammation of the lining of the heart.

What happens if CRP C-reactive protein 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.

What cancers have high CRP? ›

Additionally, elevated CRP levels are associated with poor survival in many malignant tumors, such as soft tissue sarcoma, prostate cancer, breast cancer, renal cell carcinoma, colorectal cancer, non-small-cell lung cancer, malignant lymphoma, and pancreatic cancer (10, 13-20).

What is a risky CRP level? ›

C-Reactive Protein Test Result
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
More than 50.0 mg/dLSevere elevation
1 more row
Feb 19, 2024

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.

How much CRP level is 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).

What is a positive number for rheumatoid arthritis? ›

A normal, healthy amount of rheumatoid factor is less than 20 units per milliliter (<20 U/mL). Your provider might also refer to your test as being negative or positive. A negative result means you have a normal amount of RF in your blood. Positive means you have high levels of rheumatoid factor.

What test is highly specific to rheumatoid arthritis? ›

A related blood test known as anti-cyclic citrullinated peptide (anti-CCP) test is also available. Anti-CCPs are antibodies also produced by the immune system. People who test positive for anti-CCP are very likely to develop rheumatoid arthritis, but not everybody with rheumatoid arthritis has this antibody.

What is considered a high RA level? ›

A rheumatoid factor level over 100 is strongly associated with autoimmune diseases like RA. To compare, typical findings are less than 60 u/ml. In addition to RA, a high rheumatoid factor can also point to cancer, chronic infections, Sjögren's disease, bacterial endocarditis, or other autoimmune disorders.

What is CRP in reactive arthritis? ›

When a person has an inflammatory condition like reactive arthritis, signs of inflammation are present in the blood. A blood sample may be taken to test for inflammatory markers such as: CRP. When there is inflammation in the body, the liver produces a protein called C-Reactive Protein (CRP).

What is a normal rheumatoid factor level? ›

A normal, healthy amount of rheumatoid factor is less than 20 units per milliliter (<20 U/mL). Your provider might also refer to your test as being negative or positive. A negative result means you have a normal amount of RF in your blood. Positive means you have high levels of rheumatoid factor.

How to confirm rheumatoid arthritis? ›

See a GP if you have these symptoms so they can try to determine the cause.
  1. Seeing a GP. A GP will do a physical examination, checking your joints for any swelling and to assess how easily they move. ...
  2. Blood tests. ...
  3. Rheumatoid factor and anti-CCP antibodies. ...
  4. Joint scans. ...
  5. Assessing your physical ability. ...
  6. Further information.

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