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C-reactive protein (CRP) by nephelometry (plasma)

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

This test measures the level of C-reactive protein in your blood plasma, a protein produced by the liver in response to inflammation.

Quick summary

["CRP helps identify inflammation in your body."]

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

Key facts at a glance

LOINC
56521-8
Short code
11DC 1.5h p chal SerPl-mCnc
Synonyms
11DC 1.5h p chal SerPl-mCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 conditions like infections, autoimmune diseases, or heart disease, or evaluate responses to treatments. It can also help assess risk for future health issues, such as heart disease or certain cancers.

What Does a High or Low Level Mean?

Elevated CRP levels often indicate inflammation, which can be caused by infections, injuries, or conditions like arthritis or heart disease. Very low levels may suggest no active inflammation, but they can also be influenced by factors like age, genetics, or certain medications.

Sample Preparation and Testing Process

A blood sample is drawn from a vein, typically in your arm. The plasma portion is separated and tested using nephelometry, a method that measures how particles in the sample scatter light to detect protein levels.

Common Conditions Monitored

This test is commonly used to monitor conditions such as rheumatoid arthritis, lupus, infections (like pneumonia or sepsis), heart disease, and to evaluate the effectiveness of treatments targeting inflammation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Plasma)

Frequently asked questions

What does a CRP test tell me about my health?
A CRP test provides information about whether inflammation is present in your body. High levels may signal an ongoing issue like infection, autoimmune disease, or other inflammatory conditions, but it’s not definitive on its own. Your healthcare provider will consider the results in combination with other factors, such as symptoms and medical history.
How often should I get a CRP test?
The frequency of CRP testing depends on your medical condition and treatment plan. Some people may need it regularly, while others may only need it occasionally. Your healthcare provider will determine the best schedule for you based on your specific needs and health status.
Can CRP levels change with diet or lifestyle?
While diet and lifestyle factors, such as exercise, smoking, and stress, can influence inflammation in your body, CRP levels are primarily a reflection of current inflammatory processes. However, maintaining a healthy lifestyle may help reduce overall inflammation and potentially lower CRP levels over time.
  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