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C-reactive protein (CRP) 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 doctors assess inflammation, which can be linked to infections, injuries, or autoimmune conditions."]

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

Key facts at a glance

LOINC
35952-1
Short code
CT Appendix
Synonyms
CT Appendix
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct
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 monitor conditions like arthritis, heart disease, or infections. It can also help check for signs of inflammation after surgery or injury.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into a vein (usually in your arm) to draw blood. This is quick and usually painless.

What the Results Mean

Higher CRP levels may indicate inflammation, but they can also be influenced by factors like fever, stress, or certain medications. Your doctor will interpret results in the context of your overall health.

Common Conditions Monitored

Elevated CRP is often seen in conditions like rheumatoid arthritis, lupus, or heart attack risk. It can also signal infections, such as pneumonia or appendicitis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Inflammation Marker)

Frequently asked questions

What causes CRP levels to change?
CRP levels can rise due to infections, injuries, autoimmune diseases, or certain medications. They may also fluctuate with stress, diet, or physical activity.
How often should I get this test?
Your doctor will determine how often you need this test based on your health condition and symptoms. Regular monitoring may be needed for chronic inflammation or ongoing treatment.
Can I eat or drink before the test?
You can eat and drink normally before the test unless your doctor specifies otherwise. Blood tests don’t require fasting unless directed for other reasons.
  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