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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 substance produced by your liver in response to inflammation or infection in your body.

Quick summary

["CRP helps doctors assess inflammation, track infections, or monitor conditions like arthritis or heart disease."]

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

Key facts at a glance

LOINC
35467-0
Short code
m-CPP SerPl Ql
Synonyms
m-CPP SerPl Ql
Category
chemistry
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 Might You Need This Test?

Your doctor may order CRP testing to check for signs of inflammation, monitor chronic conditions (such as rheumatoid arthritis or heart disease), or evaluate infections like pneumonia or appendicitis. It can also help guide treatment decisions for conditions like autoimmune diseases.

What Does the Test Involve?

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 Uses?

CRP is often used to screen for or monitor conditions where inflammation plays a role, such as detecting early signs of infections, assessing the activity of autoimmune diseases, or evaluating the risk of heart disease.

What Do Results Typically Mean?

Results may indicate inflammation, infection, or other health issues, but they are usually interpreted alongside other symptoms, medical history, and test results. Elevated levels may prompt further investigation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

What does a high CRP level mean?
A high CRP level often suggests inflammation or infection in your body, which may require further medical evaluation to determine the cause.
Can CRP levels change with diet or exercise?
While diet and exercise can influence overall health, CRP levels are primarily a marker of inflammation and may not be directly affected by short-term lifestyle changes.
How soon after a possible infection or injury would CRP levels start to rise?
CRP levels can begin to rise within days of an infection or injury, but the exact timing depends on the cause and individual health factors.
  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