C-reactive protein (CRP) in serum/plasma

Why CRP Matters in Your Health

CRP is a marker for inflammation, which is your body’s way of responding to injury, infection, or illness. High levels may signal conditions like infections, autoimmune diseases (such as rheumatoid arthritis), or other inflammatory processes. Your doctor may order this test to monitor your condition, check for hidden inflammation, or guide treatment adjustments.

When This Test Is Ordered

Doctors often request CRP testing if you have symptoms like fever, joint pain, or unexplained fatigue. It may also be used to evaluate conditions like heart disease, kidney disease, or to monitor chronic illnesses like lupus or rheumatoid arthritis. Some doctors check CRP levels before surgeries or during follow-ups for ongoing health concerns.

What to Expect Before the Test

No special preparation is needed for most CRP tests. If your blood is drawn, you may have a small needle inserted into your arm. If you’re having a urine test, you’ll likely collect a sample at home or in a clinic. Always follow your healthcare provider’s instructions for timing (e.g., fasting may not apply for CRP).

What the Results Mean

Results are usually reported in milligrams per liter (mg/L). A normal range isn’t always the same for everyone, as it can vary by lab and individual health. High CRP levels may indicate inflammation, while very low levels might suggest no active inflammation. Your doctor will interpret results in the context of your overall health and symptoms.