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C-reactive protein (CRP) in plasma by nephelometry

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

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

Quick summary

["CRP helps your doctor assess inflammation in your body."]

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

Key facts at a glance

LOINC
53947-8
Short code
EC stx1+stx2 + H7 fliC Spec NAA+probe
Synonyms
EC stx1+stx2 + H7 fliC Spec NAA+probe
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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

What Is C-Reactive Protein?

C-reactive protein (CRP) is a marker produced by your liver when your body experiences inflammation. It rises in response to infections, injuries, or other conditions that trigger inflammation, such as autoimmune diseases or certain chronic health conditions. CRP doesn’t specifically identify the cause of inflammation but helps track overall inflammatory activity.

Why Might You Need This Test?

Your healthcare provider may order a CRP test to monitor inflammation, check for infections, evaluate autoimmune diseases, or assess risk for heart disease. It’s often used alongside other tests to guide treatment decisions.

How Is the Test Done?

A blood sample is drawn from a vein in your arm. The plasma portion is then analyzed using nephelometry, a method that measures how much light scatters when CRP binds to antibodies.

What Do Results Mean?

Results are typically reported in milligrams per liter (mg/L). Higher CRP levels may indicate active inflammation, while lower levels suggest reduced inflammation. Interpretation depends on clinical context, including symptoms and other test results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP Plasma

Frequently asked questions

Why do I need this test?
Your doctor may use CRP levels to diagnose or monitor conditions like infections, heart disease, or inflammatory diseases. It can also help track how well your treatment is working for conditions like rheumatoid arthritis or lupus.
What if my CRP is high?
A high CRP level often signals inflammation, but it doesn’t always point to a specific cause. Your doctor will review your symptoms, medical history, and other tests to determine the next steps, such as further evaluation or treatment adjustments.
How often should I get this test?
Frequency depends on your health condition and treatment plan. Your doctor will let you know if regular monitoring is needed, such as for chronic diseases or after a recent injury or illness.
  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