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C-reactive protein (CRP) by nephelometry

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

This test measures the level of C-reactive protein in your blood, a marker often used to assess inflammation or infection.

Quick summary

["CRP helps track inflammation, guiding decisions about treatments or further testing."]

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

Key facts at a glance

LOINC
6503-7
Short code
N men sg Y Ag CSF Ql IA
Synonyms
N men sg Y Ag CSF Ql IA
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order CRP testing to check for signs of inflammation, infection, or other health conditions like heart disease or autoimmune disorders. It can also help monitor responses to treatments.

What Does a High or Low CRP Level Mean?

Elevated CRP levels often indicate inflammation or infection, but they can also be raised due to other factors like stress, certain medications, or chronic conditions. Low levels may suggest reduced inflammation, but they don’t always mean you’re healthy.

Sample Collection and Preparation

A blood sample is drawn from a vein, usually in your arm. The blood is processed to separate serum or plasma for testing. This test does not require fasting.

Common Conditions Monitored

CRP is commonly used to monitor conditions like rheumatoid arthritis, infections (e.g., pneumonia, sepsis), and to evaluate the risk of heart disease or stroke. It may also be checked after surgery or injury to track healing progress.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP (Nephelometry)

Frequently asked questions

What Does CRP Measure?
CRP is a protein produced by the liver in response to inflammation or infection. It rises quickly in the bloodstream when your body is fighting illness or injury.
How Often Should I Get Tested?
The frequency depends on your medical condition and treatment plan. Your healthcare provider will determine how often to check CRP levels based on your needs.
Can CRP Levels Change Without a Clear Cause?
Yes, CRP can be elevated due to stress, recent illness, or certain medications. It’s important to discuss any concerns with your provider to understand the context.
  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