Skip to content

C-reactive protein (CRP) – Serum

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of C-reactive protein in your blood, which is a marker of inflammation.

Quick summary

["CRP helps doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or heart disease."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
77491-9
Short code
Deprecated Hind+Mid ft-L XR Ski Jump
Synonyms
Deprecated Hind+Mid ft-L XR Ski Jump
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order a CRP test to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or evaluate symptoms such as fever, joint pain, or swelling. It can also help determine if an infection is present or if your body is overreacting to an injury or illness.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually takes just a few minutes. If you’re on blood-thinning medication, let your doctor know before the test.

What to Expect During the Test

You’ll sit comfortably while a healthcare professional collects a blood sample from your arm. You might feel a slight pinch, but it’s generally quick and painless. The test itself is simple and doesn’t require any special care afterward.

Possible Results and Next Steps

Results may be reported as higher or lower than a reference range, but exact values aren’t provided here. Elevated CRP levels often signal inflammation, while normal levels suggest minimal inflammation. Your doctor will discuss the results with you and may recommend further testing or treatment if needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP is a useful marker for identifying and monitoring inflammation in the body. High levels can indicate infections, autoimmune diseases, or inflammatory conditions like heart disease or certain cancers. It’s also sometimes used to assess response to treatment or monitor disease activity in chronic conditions.

Short name

CRP

Frequently asked questions

How often should I get a CRP test?
The frequency depends on your health condition and why the test was ordered. Your doctor will determine how often you need it based on your medical needs, such as monitoring a chronic illness or evaluating symptoms of inflammation.
Can food or medications affect CRP levels?
While diet and exercise can influence inflammation, CRP levels are primarily a measure of your body’s response to inflammation rather than diet-specific. Some medications, like steroids, may affect CRP levels, so always inform your doctor about all medications you’re taking.
What does a high CRP level mean?
A high CRP level often signals inflammation, which could be due to infections, autoimmune diseases, or other inflammatory conditions. Your doctor will review your results in the context of your symptoms and medical history to determine the best next steps.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy