C-reactive protein (CRP) concentration, serum/plasma

Why CRP Testing Matters

CRP is a marker that signals your body’s immune response. High levels may indicate infections, autoimmune diseases, or other inflammatory processes. Your doctor may order this test to assess risk for conditions like heart disease or to monitor treatment progress for conditions such as rheumatoid arthritis or infections like pneumonia.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic or liver panel. Bring any medications you’re currently taking, as some may affect results.

Common Uses of CRP Testing

Doctors often use CRP to evaluate suspected infections (e.g., urinary tract infections, sepsis), track chronic inflammatory diseases (e.g., lupus, inflammatory bowel disease), or assess cardiovascular risk. It can also guide decisions about starting or adjusting medications.

How Results Are Interpreted

Results are typically reported in milligrams per liter (mg/L). While reference ranges vary by lab, very high levels (above 10 mg/L) often signal severe inflammation or infection. Your doctor will interpret results in the context of your symptoms and medical history.