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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 inflammation, which can signal infections, injuries, or other health issues."]

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

Key facts at a glance

LOINC
26108-1
Short code
XR Clavicle-R Views
Synonyms
XR Clavicle-R Views
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 conditions like arthritis, heart disease, or infections, or evaluate how your body responds to treatment for these conditions.

What Does a High CRP Level Mean?

Elevated CRP levels often indicate inflammation. While it doesn’t specify the cause, high levels can signal infections, autoimmune diseases, or other inflammatory processes that may need further investigation.

What Does a Low CRP Level Mean?

Low CRP levels usually mean there is little to no inflammation detected in your body. However, a very low level might not rule out mild inflammation, so results should always be interpreted by your healthcare provider.

How Is the CRP Test Performed?

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

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

CRP is a non-specific marker, meaning it rises in response to many types of inflammation. Doctors use it to monitor chronic conditions like rheumatoid arthritis or cardiovascular risks, track healing after surgery or injury, or diagnose infections.
Your CRP test results will be reviewed by your healthcare provider alongside other tests and symptoms to determine the best course of action.
What are the typical reference ranges for CRP?
CRP reference ranges vary by lab and individual health status. Low levels (typically below 1 mg/L) suggest minimal inflammation, while higher levels (above 10 mg/L) may indicate significant inflammation or infection. Your results should be discussed with your doctor.
Can CRP levels change over time?
Yes, CRP levels can fluctuate based on your health status, recent illnesses, medications, or lifestyle factors like diet and exercise. Regular monitoring may be needed for chronic conditions.
  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