FaridabadBy Dr B.C. Gupta, MD · 2026-09-15
A CRP test measures C-reactive protein, a substance the liver makes when there is inflammation somewhere in the body. It is one of the most commonly ordered blood tests when a doctor wants to know whether inflammation or infection is present.
What does the test measure?
The test measures the level of C-reactive protein in your blood. The level rises within hours when inflammation starts and falls again as it settles, which makes it useful for watching how an illness is progressing. A quantitative CRP gives a number, while a qualitative CRP gives a positive or negative result.
How is it different from ESR?
ESR, the erythrocyte sedimentation rate, is another marker of inflammation. Both are often ordered together. CRP tends to rise faster and fall faster, so it can reflect a sudden infection sooner, while ESR changes more slowly. Neither test says where the inflammation is or what is causing it, so the doctor uses them along with your symptoms.
How to prepare
The sample is a blood draw. Fasting is not usually needed for CRP. Results are often available the same day for the standard test.
What a raised result can mean
A raised CRP can occur with many conditions. Common causes include bacterial infection, viral illness, and inflammatory conditions such as arthritis. It can also rise after injury or surgery. A normal CRP does not rule out every illness, and a raised one does not by itself identify the cause, so the result is always read together with your history and examination.
When is it ordered?
Doctors order CRP to look for infection when the cause of fever or illness is unclear, to assess joint pain and swelling, and to follow up on a known inflammatory condition. It is included in the centre's arthritis screen and arthritis comprehensive profile, along with RA factor, ESR and uric acid.
This article is for general information only and is not medical advice. Always discuss your results and any health concerns with your doctor.
