Inflammation
CRP blood test: what a high result means
What a CRP (C-reactive protein) result means, why CRP can be raised, and what to ask your doctor.
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Explain my results → Available on web, iOS & Android.What is CRP?
CRP, or C-reactive protein, is made by your liver and released into the blood when there is inflammation somewhere in the body. It rises within hours of an infection or injury and falls as you recover, so it is useful for spotting and tracking inflammation. CRP does not show where the inflammation is or what is causing it. A high-sensitivity CRP (hs-CRP) test is sometimes used to assess heart disease risk, mainly in the US; it is not routinely used for this in the NHS.
Why is this test done?
- To check for infection or inflammation
- To monitor inflammatory conditions, such as rheumatoid arthritis or inflammatory bowel disease
- To see whether treatment, such as antibiotics, is working
- After surgery, to check for complications
What does a high CRP mean?
A raised CRP means there is inflammation in the body. A small rise is very common; a large rise suggests a more significant infection or inflammation.
Possible reasons include:
- Bacterial or viral infections
- Inflammatory conditions, such as rheumatoid arthritis or Crohn's disease
- Recent surgery or injury
- Obesity and smoking, which can cause mild rises
- Some cancers
What does a low CRP mean?
A low CRP makes significant inflammation less likely, but it does not rule it out completely, for example very early in an infection or in some conditions and treatments.
Why we don't list a "normal range". Reference ranges differ between laboratories and can depend on your age, sex and whether you are pregnant. The range printed next to your result on your own report is the one that applies to you, so use that, and talk to your doctor about what your result means for you.
What can affect your CRP result?
- Recent infection, including minor colds
- Recent surgery, injury or hard exercise
- Pregnancy
- Medicines that reduce inflammation, such as steroids
- Some medicines that dampen the immune system, such as tocilizumab and JAK inhibitors (for example baricitinib or upadacitinib), which can stop CRP rising even during serious infection
Make sense of the whole report, not just one line
Results are easier to understand together. Patiently AI explains your report as a whole and writes personalised questions for your next appointment.
Try it with your own results → Paste, upload or photograph your results.Questions to ask your doctor
- What do you think is causing the inflammation?
- Is my CRP going up or down compared with before?
- Do I need other tests to find the cause?
- When should it be rechecked?
Frequently asked questions
What is the difference between CRP and ESR?
Both are markers of inflammation. CRP rises and falls quickly, within days. ESR changes more slowly and is affected by more factors, such as age and anaemia. Doctors often use them together.
Can a cold raise my CRP?
Yes. Even minor infections can cause a small rise in CRP that settles once you recover.
Does a high CRP mean something serious?
Not necessarily. CRP rises with many common, temporary problems. Your doctor will interpret it with your symptoms and other test results.
Can Patiently AI explain my CRP result?
Yes. Paste your results, or upload a photo, PDF or Word file, and Patiently AI explains them in plain English, sticking to the numbers and ranges on your own report rather than adding its own, and suggests questions to ask your doctor. It is free, needs no account, and removes identifying details on your device first.