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CRP

A protein the liver releases within hours of inflammation starting anywhere in the body. It rises fast and falls fast, which makes it useful for tracking an active process — but it says nothing about where the inflammation is or what is causing it. A separate, more sensitive assay (hs-CRP) is used in cardiovascular risk research and reports much smaller numbers.

General information only — not a diagnosis, not treatment and not a substitute for your doctor. Reference ranges differ between laboratories, so the range printed on your own report is the one that counts, and only a clinician who knows your history can say what a result means for you. Never start, stop or change a medicine or supplement based on this page.

Usual adult reference range

The ranges below are typical adult reference intervals. Your own laboratory sets its own, printed next to your result, and that is the one to compare against.

Source: Typical adult reference interval published by clinical laboratories; the high-sensitivity assay used for cardiovascular risk stratification reports on a different scale. · checked 2026-09-02

What a high result generally indicates

A raised CRP means something inflammatory is happening: infection, injury, surgery, an autoimmune flare, and at the top of the range usually bacterial infection. The size of the rise is a rough guide to intensity, not to cause. Interpretation always needs the clinical picture.

What a low result generally indicates

A low or undetectable CRP is the normal state and is reassuring about active inflammation at that moment. It does not exclude every disease — some inflammatory conditions run with a normal CRP.

These are general patterns, not a diagnosis. Many things cause a high or low result, and the same figure means different things in different people. What yours means is a question for the doctor who ordered the test.

What affects this result

• Any recent infection, including a cold, raises it for days.
• Surgery and injury raise it steeply and predictably.
• Obesity raises baseline levels modestly.
• Smoking raises it; stopping lowers it.
• Oestrogen-containing contraceptives and hormone therapy raise it.
• Vigorous unaccustomed exercise raises it for a day or two.

Before the test

No fasting needed. Recent illness is worth mentioning to whoever ordered the test.

Any preparation instruction that comes with your test slip overrides this general note — follow the one your clinician or laboratory gave you.

The one thing to take from this page

The range above is a typical interval for orientation. Your own laboratory's range, printed beside your result, is the one that applies to you — and a result is only meaningful alongside your symptoms, your history, your medicines and your other tests. That reading is a clinician's job. This page cannot diagnose anything, cannot tell you to change a medicine or a supplement, and is not a substitute for the person who ordered your test.

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