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C-reactive protein (serum/plasma concentration)

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

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

Quick summary

["CRP helps doctors assess inflammation, track infections, or monitor conditions like autoimmune diseases."]

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

Key facts at a glance

LOINC
21774-5
Short code
Chr 9 Ts Bld/T Ql
Synonyms
Chr 9 Ts Bld/T Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
cytogenetics
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is C-Reactive Protein Used For?

CRP is often used to monitor general inflammation in the body. It can help diagnose infections (such as pneumonia or urinary tract infections), track how well treatments for autoimmune diseases (like rheumatoid arthritis) are working, or check for signs of inflammation after surgery or injury.

How Is This Test Performed?

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

What Might High or Low CRP Levels Indicate?

Elevated CRP levels may suggest inflammation, infection, or an autoimmune condition. Very low levels might indicate a lack of inflammation, though they can also be due to certain medications or medical conditions. Your doctor will interpret results in the context of your symptoms and other tests.

How Often Is This Test Done?

The frequency depends on your health needs. Some people get CRP tested annually as part of a general health check, while others may have it done more often if they have chronic conditions like heart disease or arthritis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP plays a key role in identifying and managing conditions tied to inflammation. It’s a simple blood test that can help prevent complications by catching issues early, such as heart disease or infections. However, CRP alone isn’t diagnostic—it’s used alongside other tests and clinical findings.

Short name

CRP

Frequently asked questions

Why might my CRP test be done without symptoms of illness?
Your doctor may order a CRP test to monitor chronic conditions (like heart disease or arthritis), check for hidden inflammation, or assess recovery after surgery or an injury.
What could affect my CRP levels?
Factors like infections, injuries, stress, certain medications, or autoimmune diseases can raise CRP levels. Smoking, obesity, or poor diet may also influence results.
Can I prepare for this test?
No special preparation is needed, but avoid heavy meals or alcohol before the blood draw if instructed by your doctor.
  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