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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, which may signal infections, autoimmune conditions, or other health issues."]

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

Key facts at a glance

LOINC
50772-3
Short code
GQ1b Gangl IgG/IgM Ser IA-Rto
Synonyms
GQ1b Gangl IgG/IgM Ser IA-Rto
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
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 monitor conditions like infections, arthritis, or other inflammatory diseases. It can also help check for signs of inflammation after surgery or injury.

What Does a High or Low CRP Level Mean?

Elevated CRP levels may indicate an active infection, inflammation, or autoimmune disorder. Lower-than-normal levels might suggest reduced inflammation, but they don’t always mean you’re healthy.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The lab uses a special method called nephelometry to measure CRP levels accurately.

What Are Common Causes of Abnormal Results?

High CRP can be caused by infections (like pneumonia or urinary tract infections), autoimmune diseases (like rheumatoid arthritis), or other inflammatory conditions. Low CRP may occur with certain infections or after successful treatment of inflammation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP is a useful marker for monitoring inflammation but isn’t diagnostic on its own. It’s often used alongside other tests or symptoms to guide treatment decisions.

Short name

CRP (Neph)

Frequently asked questions

What does a CRP test measure?
A CRP test measures the amount of C-reactive protein in your blood, a protein produced by your liver in response to inflammation or infection.
Can CRP levels change with diet or exercise?
Diet and exercise can sometimes influence inflammation, but CRP levels are primarily a reflection of your body’s current inflammatory state, not just lifestyle factors alone.
How soon after a procedure or injury can CRP levels return to normal?
It depends on the cause—some people see CRP levels drop within days, while others may take weeks or longer, especially if inflammation is severe or ongoing.
  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