The body produces C-reactive protein (CRP) in response to inflammation. Measuring CRP levels in the blood can help with diagnosing and monitoring rheumatoid arthritis.
Blood tests can help confirm a diagnosis of RA. People with the disease often have elevated levels of certain proteins, including C-reactive protein (CRP), in their blood.
In this article, we look at the link between RA and CRP. We describe what CRP levels show and how to reduce them.
The liver makes CRP, a type of protein. When the immune system signals inflammation, the body sends CRP through the bloodstream to the affected area. Doctors measure CRP by how many milligrams there are in a liter of blood (mg/l).
High levels of CRP in the blood indicate chronic inflammation. This occurs with a wide range of health problems, such as:
Healthcare professionals measure CRP by analyzing blood samples. They typically take these measurements as part of regular diagnosis and management. A person does not need to fast beforehand.
In some cases, a doctor will request a high-sensitivity CRP (hs-CRP) test for a more accurate measurement. Usually, they do so when there is a risk of another issue, such as heart disease.
Like any other test involving a needle, a CRP test can cause:
Individual factors, such as age and medical history, can all affect CRP levels.
|CRP level (mg/L)||Assessment|
|Less than 0.3||A typical level in healthful adults|
|0.3 – 1||Minor elevation|
|More than 50||Severe elevation|
Conditions such as minor colds, pregnancy, and smoke inhalation can cause minor RCP elevation.
High levels of CRP mean there is inflammation in the body. This can help doctors to diagnose and manage RA.
For example, doctors may measure a person’s CRP levels during a treatment program to assess how effectively specific methods are reducing inflammation.
Complications of high levels
Over time, RA can cause complications. These may involve other parts of the body and elevated levels of inflammation. For this reason, doctors can monitor CRP levels to assess the risk of these complications.
For example, people with RA have an increased risk of heart disease. A doctor can assess an individual’s risk with a hs-CRP test, and a result above 3 mg/l indicates that the risk is high.
Other causes of high CRP levels
A wide variety of health conditions can cause inflammation, and determining why CRP levels are high usually requires further investigations.
The following factors can affect the results of a CRP test:
Prescription medications can reduce inflammation. The other goals of RA treatment are to relieve pain, manage symptoms, and reduce or eliminate the risk of permanent joint damage.
To reduce inflammation, a person may take:
- over-the-counter or prescription nonsteroidal anti-inflammatory drugs (NSAIDs)
- disease-modifying antirheumatic drugs (DMARDs), which suppress the immune system
- biologics, which can slow down or prevent the progression of RA
Doctors may recommend the use of DMARDs alongside NSAIDs and biologics. A doctor can also inject steroid-based medication directly into a joint to decrease inflammation.
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. Taking RA medications can help reduce levels of inflammation and CRP in the blood.