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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 the 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
35897-8
Short code
CT Guided UE Bx
Synonyms
CT Guided UE Bx
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct
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 chronic conditions like arthritis or heart disease, or evaluate responses to treatments. It can also help diagnose infections or assess risk for certain health issues.

What Does a High CRP Level Indicate?

Elevated CRP levels often signal inflammation, which can be caused by infections, injuries, autoimmune diseases, or other health problems. However, a single high result doesn’t always mean an immediate issue—your doctor will consider other factors.

What Does a Low CRP Level Indicate?

Low CRP levels usually mean there is little to no inflammation in your body, which may be normal if you’re healthy. However, very low levels can sometimes raise concerns about underlying conditions that need further evaluation.

How Is This Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it is analyzed using nephelometry, a method that measures how much light is scattered by the protein in your blood.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP plays a key role in identifying and managing inflammatory conditions. It’s often used alongside other tests to guide treatment decisions, such as adjusting medications for conditions like rheumatoid arthritis or monitoring recovery from surgery or infection.

Short name

CRP (Serum/Plasma)

Frequently asked questions

What does a CRP test measure?
A CRP test measures the concentration of C-reactive protein in your blood, which rises when your body is inflamed or fighting infection.
Can CRP levels change over time?
Yes, CRP levels can fluctuate depending on your health status, recent infections, medications, or other factors. Your doctor will interpret results in the context of your overall health and medical history.
Does diet affect CRP levels?
Yes, diet can influence CRP levels. Eating a balanced diet rich in fruits, vegetables, and omega-3 fatty acids may help reduce inflammation, while unhealthy diets high in processed foods can increase CRP levels.
  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