C-reactive protein (CRP) mass concentration in serum/plasma

Why Is This Test Done?

Your doctor may order a CRP test to check for signs of inflammation in your body. This can help diagnose conditions like infections (e.g., pneumonia), autoimmune diseases (e.g., rheumatoid arthritis), or to monitor how well you’re responding to treatment for these conditions. It may also be used before surgery or to assess risk for heart disease.

What Does a High or Low CRP Level Mean?

A high CRP level often indicates inflammation, which can be caused by infections, injuries, or certain medical conditions. A low CRP level usually means there’s less inflammation. However, CRP alone doesn’t diagnose a specific condition—it’s often used alongside other tests for a full picture.

How Is the CRP Test Performed?

A small blood sample is taken from a vein in your arm. The blood is then sent to a lab where it’s analyzed to measure CRP levels. The test typically takes a few minutes to collect, and results are usually available within a few days.

What Are Common Causes of Abnormal CRP Levels?

CRP levels can be elevated due to infections (like flu or pneumonia), injuries, surgeries, or certain medical conditions such as rheumatoid arthritis, lupus, or heart disease. They may also rise after childbirth or during stress. Low CRP levels might suggest a lack of inflammation, but they can also occur in people with very mild or chronic conditions.