CRP Test

The C-Reactive Protein (CRP) test is a blood test that measures the level of C-reactive protein in the blood. CRP is a protein produced by the liver and sent into the bloodstream in response to inflammation.

Purpose of the Test

The CRP test is used to:

• Detect and monitor inflammatory conditions such as infections, autoimmune disorders, and inflammatory diseases like rheumatoid arthritis and lupus
• Evaluate the severity of inflammation in the body
• Monitor the effectiveness of treatment for inflammatory conditions
• Assist in diagnosing and monitoring conditions such as coronary artery disease, stroke, and peripheral arterial disease

How the Test is Performed

A healthcare provider will:

• Take a blood sample from a vein in the arm using a needle and syringe or a finger prick
• Send the blood sample to a laboratory for analysis
• The laboratory will measure the level of CRP in the blood using a specialized test

Interpretation of Results

The results of the CRP test are measured in milligrams per liter (mg/L) or milligrams per deciliter (mg/dL). The normal range for CRP is:

• Less than 10 mg/L: Normal
• 10-100 mg/L: Mildly elevated, may indicate a low-grade inflammatory response
• 100-500 mg/L: Moderately elevated, may indicate a moderate inflammatory response
• Above 500 mg/L: Highly elevated, may indicate a severe inflammatory response or infection

Risk Factors and Limitations

The CRP test is not specific to any particular condition and can be influenced by various factors, including:

• Pregnancy and menstruation
• Obesity
• Aging
• Certain medications, such as oral contraceptives and steroids
• Recent surgery or trauma

Types of CRP Tests

There are two types of CRP tests:

• Standard CRP test: Measures the level of CRP in the blood, but may not detect low levels of inflammation
• High-sensitivity CRP (hs-CRP) test: More sensitive than the standard CRP test and can detect lower levels of inflammation, often used to evaluate cardiovascular risk