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C-reactive protein (CRP) by nephelometry (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, often used to monitor conditions like infections or autoimmune diseases."]

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

Key facts at a glance

LOINC
33935-8
Short code
cCP IgG SerPl-aCnc
Synonyms
cCP IgG SerPl-aCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 check for signs of inflammation, monitor chronic conditions like arthritis or heart disease, or evaluate responses to treatments. It can also help diagnose infections or assess risks for certain health issues.

What Does a High or Low CRP Level Mean?

A high CRP level often signals inflammation, which can be due to infections, injuries, or autoimmune diseases. A low level may indicate no active inflammation, but it doesn’t rule out other conditions. Your results will be interpreted by your doctor in the context of your overall health.

How Is the Test Performed?

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

What Are Common Causes of Abnormal Results?

High CRP levels can be caused by infections (like pneumonia or urinary tract infections), autoimmune diseases (such as rheumatoid arthritis), heart disease, or other inflammatory conditions. Low levels may occur with no inflammation, but can also be influenced by medications or certain health conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP (Nephelometry)

Frequently asked questions

What questions might I have about this test?
This test is often used as a general marker for inflammation and can help guide treatment decisions. It’s not specific to any single condition but provides a broad overview of your body’s inflammatory response. If you have specific symptoms or concerns, discuss them with your healthcare provider.
How often should I get this test?
The frequency depends on your medical condition and treatment plan. Your doctor will determine how often you need this test based on your individual needs and health status. Regular monitoring may be necessary for chronic conditions like arthritis or heart disease.
Can I prepare for this test?
No special preparation is needed for this blood test. You may have some discomfort from the needle, but it usually goes quickly. If you are on blood thinners or have a history of bleeding issues, let your healthcare provider know before the test.
  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