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C-reactive protein (CRP) concentration in serum/plasma

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

This test measures the level of C-reactive protein, a protein produced by your liver in response to inflammation in your body.

Quick summary

["CRP helps identify inflammation, often used to monitor conditions like infections or autoimmune diseases."]

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

Key facts at a glance

LOINC
6353-7
Short code
C trach Ag Tiss Ql IF
Synonyms
C trach Ag Tiss Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 CRP Matters

CRP is a marker for inflammation, which can occur due to infections, injuries, or certain medical conditions. High levels may signal an active inflammatory process, helping doctors assess risk for conditions like heart disease or rheumatoid arthritis.

What Does CRP Tell You?

CRP levels can indicate whether inflammation is present but don’t always pinpoint the exact cause. It’s often used alongside other tests to guide treatment decisions.

When Is This Test Ordered?

Your doctor may order CRP testing to check for infections, monitor chronic conditions (like arthritis or heart disease), or evaluate symptoms like fever, pain, or swelling.

What to Expect Before the Test

No special preparation is needed. A blood sample is taken from a vein, usually in your arm. You may feel a slight pinch, but it’s quick and painless.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

How long does it take to get my CRP results?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will discuss them with you during your follow-up visit.
Can I eat or drink before this test?
You can eat and drink normally before the test. No fasting is required.
Does CRP change with age or gender?
Yes, CRP levels can vary with age, health status, and certain medications. Your doctor will consider these factors when interpreting your results.
  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