✍️ Edited by Farhan Ahmed, Editor, MedTestBD · Last updated: July 2026
What is CRP?
C-Reactive Protein (CRP) is a protein produced by the liver in response to inflammation anywhere in the body. When tissues are damaged, infected, or inflamed, the liver rapidly releases CRP into the bloodstream. Because of this, CRP is one of the most useful and fast-responding markers of inflammation and infection available in routine blood testing.
Why is the CRP Test Done?
- To detect or confirm the presence of a bacterial infection (CRP rises very quickly — within hours of infection onset).
- To differentiate between bacterial and viral infections — CRP tends to rise much higher in bacterial infections.
- To monitor the progress of treatment — if CRP falls, the infection or inflammation is responding to treatment.
- To evaluate inflammatory conditions like rheumatoid arthritis, lupus, or inflammatory bowel disease.
- After surgery, to detect post-operative complications.
- High-sensitivity CRP (hs-CRP) — a more sensitive version — is used to assess cardiovascular disease risk.
Normal CRP Levels
- Normal: Less than 10 mg/L
- Mild inflammation: 10–40 mg/L
- Moderate to severe infection or inflammation: Above 40 mg/L
- Severe bacterial infection or major trauma: Can exceed 200 mg/L
A single CRP reading is not a diagnosis. It tells the doctor that inflammation exists, but not the exact cause. Follow-up tests and clinical assessment are always needed.
How to Prepare for the CRP Test
No special preparation or fasting is required for a standard CRP test. However, inform your doctor if you are currently taking anti-inflammatory medications like ibuprofen or corticosteroids, as these can artificially lower CRP values and affect interpretation.
CRP vs ESR — What is the Difference?
Both CRP and ESR (Erythrocyte Sedimentation Rate) are markers of inflammation, but CRP responds much faster — rising within 6–12 hours of an inflammatory stimulus, while ESR may take days. CRP is also more specific and returns to normal more quickly once the inflammation resolves, making it better for monitoring treatment progress.
Normal ranges cited on this page are based on MedlinePlus and WHO guidance. Prices are collected from public sources and may change — confirm with the facility before visiting. This information is for general reference only and is not medical advice. Always consult a qualified physician.
