C-reactive protein (CRP) by nephelometry

Your doctor may order a CRP (C-reactive protein) blood test when they suspect inflammation somewhere in your body. It is often used to look into symptoms such as fever, fatigue, or unexplained pain, to monitor a long-term condition, or to see whether a treatment is working as expected.

Your healthcare provider may order this test to check for early signs of inflammation, monitor conditions like autoimmune diseases, or evaluate risk factors for heart disease or other health issues. High-sensitivity CRP is particularly useful for detecting mild inflammation that might not be detected by standard CRP tests.

Very little preparation is needed for a CRP blood test. You can usually eat and drink normally beforehand, and you can generally keep taking your regular medications unless your doctor tells you otherwise. Let the person drawing your blood know if you have ever felt faint during a blood draw.

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on blood thinners, let your provider know before the test.

CRP results are reported in milligrams per liter (mg/L). Higher-than-normal levels usually point to inflammation somewhere in the body, which may come from an infection, an injury, or a chronic illness. A single high result does not reveal the exact cause, so your doctor will review it alongside your symptoms and other test results.

Results are not provided as a single numeric range since reference values vary by lab and condition. Your provider will interpret the result in relation to your overall health and symptoms. Elevated levels may suggest inflammation, infection, or other underlying health concerns.

CRP testing is commonly used to follow conditions that involve ongoing inflammation, such as rheumatoid arthritis, lupus, inflammatory bowel disease, infections, and recovery after surgery or injury. Repeat tests over time can show whether treatment is bringing inflammation under control.

This test is often used to monitor conditions such as cardiovascular risk, rheumatoid arthritis, lupus, or other inflammatory diseases. It can also help guide treatment decisions for chronic conditions.