A CRP (C-reactive protein) test is a blood test that measures inflammation in your body. The liver releases CRP quickly in response to infection, injury or inflammatory disease. A standard CRP below 10 mg/L is generally normal. A related test, high-sensitivity CRP (hs-CRP), detects much lower levels and is used to assess heart disease risk.
What does the CRP test measure?
C-reactive protein is made by your liver and released into the blood within hours of inflammation starting anywhere in the body. Levels can rise a hundred-fold during a serious bacterial infection, then fall within days as it settles. That speed makes CRP useful for tracking whether an infection or flare-up is getting better.
CRP does not tell you where inflammation is or what is causing it, so doctors always read it alongside symptoms and other tests. There are two versions, and they answer different questions:
- Standard CRP: Measures higher levels. Used when infection or an inflammatory condition (such as rheumatoid arthritis or inflammatory bowel disease) is suspected, and to monitor treatment.
- High-sensitivity CRP (hs-CRP): Measures very low levels of ongoing, low-grade inflammation in the blood vessels. Used with a lipid profile to refine heart disease risk in people without obvious illness.
Because chronic low-grade inflammation is linked to heart disease, diabetes and obesity, hs-CRP has become a common add-on in corporate and executive health checkups.
CRP normal range
(many labs use below 5 or 6)
Where does your result fall?
Enter your hs-CRP value from your report. Use this for an hs-CRP result. A standard CRP report is read differently.
A general guide, not a diagnosis. The reference range on your own report takes priority, and a doctor should interpret any result outside it.
An hs-CRP above 10 mg/L usually reflects an acute infection or illness rather than heart risk; the test is repeated after you recover. Some labs report in mg/dL (divide mg/L by 10). Ranges vary between labs and methods. Always compare your result with the reference range printed on your own report.
What abnormal results can mean
- Mildly raised CRP: Can follow a cold, minor injury, smoking, obesity, poor sleep or pregnancy.
- Markedly raised CRP: Can suggest a bacterial infection, an autoimmune flare, or tissue injury.
- hs-CRP above 3 mg/L on repeat testing: Can suggest higher long-term heart risk, especially with high LDL or diabetes.
A single CRP value is a clue, not a diagnosis. Discuss it with your doctor.
Who should get this test?
- People with fever or signs of infection where the doctor wants to judge severity.
- People with joint pain, swelling or stiffness or a known autoimmune condition.
- People being treated for an infection or inflammatory disease, to track progress.
- Adults assessing heart risk (hs-CRP), especially with a family history of early heart disease or borderline cholesterol.
- Preparation: No fasting needed for CRP, but if booked with a lipid profile, follow fasting instructions. For hs-CRP, avoid testing during or just after a cold or other illness.
This page is for general information and is not a substitute for medical advice. Always interpret your results with a qualified doctor.