CRP (C-Reactive Protein) levels, explained
CRP is a protein made by the liver that rises with inflammation anywhere in the body — a general marker of inflammatory activity.
What’s a normal CRP level?
Typical adult reference range, shown for orientation. Your report’s range may differ by lab, age, and sex — the analyzer uses your report’s own ranges when available.
What high and low CRP mean
A value outside the reference range is a flag, not a diagnosis. Here’s what each direction usually points to — and the most common causes.
High CRP signals active inflammation somewhere in the body — it tells you inflammation is present, but not where or why.
- Infection (bacterial or viral)
- Chronic inflammatory or autoimmune disease
- Tissue injury or recent surgery
- Obesity, smoking, or cardiovascular risk (mild hs-CRP elevation)
A low CRP is the desirable result — it indicates little or no measurable inflammation.
- Absence of significant inflammation (the normal, healthy state)
When a CRP result needs attention
A markedly high CRP (often >100 mg/L), or a rising CRP with fever or feeling unwell, suggests significant infection or inflammation and warrants prompt evaluation.
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CRP (C-Reactive Protein) — frequently asked questions
- What does a high CRP level mean?
- A high CRP means there is active inflammation in the body, but it is non-specific — it does not say where or why. Common causes include infection, injury or surgery, and chronic inflammatory or autoimmune conditions. Very high levels usually point to significant infection or inflammation.
- What is the difference between CRP and hs-CRP?
- They measure the same protein, but hs-CRP (high-sensitivity CRP) detects much lower concentrations. Standard CRP is used to track infection and inflammatory disease; hs-CRP is used to assess cardiovascular risk, where small differences in low-level inflammation matter.
- Can lifestyle lower CRP?
- Yes, for the low-grade inflammation reflected by hs-CRP. Losing excess weight, exercising, stopping smoking, improving sleep, and an anti-inflammatory diet can lower it. CRP driven by an acute infection or flare instead falls as the underlying cause resolves.
Related lab markers
- Ferritin →Ferritin is the protein that stores iron in your body — it is the single best blood marker of how much iron you have in reserve.
- ALT (Alanine Aminotransferase) →ALT is a liver enzyme released into the blood when liver cells are stressed or damaged — one of the most sensitive markers of liver health.
- Hemoglobin →Hemoglobin is the protein in red blood cells that carries oxygen — low hemoglobin defines anemia.
- All lab markers →Browse every biomarker guide in one place.
This page provides educational health information and does not replace professional medical advice, diagnosis, or treatment. Interpret any lab value with your clinician, who has your full medical context. For emergencies, contact emergency services.