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

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

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

Quick summary

["CRP helps identify and monitor inflammation, often used to check for infections or other inflammatory conditions."]

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

Key facts at a glance

LOINC
13272-0
Short code
N men sg C Ab Ser-aCnc
Synonyms
N men sg C Ab Ser-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 healthcare provider may order this test to evaluate signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, check for infections (such as bacterial infections), or assess response to treatment for inflammatory diseases.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast before the test if it’s done on an empty stomach, but this depends on the lab’s protocol. Bring any medications you’re taking to your appointment.

How the Test Works

A small sample of your blood is drawn from a vein, typically in your arm. The blood is then sent to a lab where it is analyzed to measure CRP levels using an immunoassay method.

What the Results Mean

Results are reported as a concentration value (e.g., milligrams per liter). Higher than normal levels may indicate inflammation, infections, or other health issues. Your provider will interpret the results in the context of your medical history and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP (Serum/Plasma)

Frequently asked questions

What causes CRP levels to be higher than usual?
CRP can rise due to infections (like pneumonia or urinary tract infections), injuries, surgeries, or certain medical conditions such as autoimmune diseases (e.g., rheumatoid arthritis). Stress, smoking, or certain medications may also temporarily affect CRP levels.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on the lab’s processing time. Your healthcare provider will contact you once they have the results.
Can I eat or drink before this test?
Most labs do not require fasting for CRP testing, but always follow your provider’s instructions. If fasting is required, avoid food and liquids (except water) for 8–12 hours before the test.
  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