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C-reactive protein (CRP) by nephelometry

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

This blood test measures the level of C-reactive protein, a protein made by your liver that rises in response to inflammation in your body.

Quick summary

["CRP helps doctors check for inflammation, which can signal infections, injuries, or other health issues."]

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

Key facts at a glance

LOINC
94653-3
Short code
City of trav
Synonyms
City of trav
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

What Is C-Reactive Protein Used For?

CRP is often used to monitor conditions like heart disease, autoimmune disorders, or infections. High levels may indicate inflammation that needs further investigation.

How Is This Test Done?

A small blood sample is taken from your arm, usually by a healthcare professional. The lab then uses a special method (nephelometry) to measure CRP levels in your serum.

Why Might I Need This Test?

Your doctor may order this test to assess inflammation, track chronic conditions, or evaluate symptoms like fever, joint pain, or unexplained fatigue.

What Are Common Results?

Results are not given in absolute numbers here, but doctors compare them to your individual baseline or clinical context. Very high levels may need further testing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a marker for systemic inflammation. Elevated levels can signal infections, autoimmune diseases, or other inflammatory processes, guiding treatment decisions.

Short name

CRP (High-Sensitivity)

Frequently asked questions

Why do I need a high-sensitivity CRP test?
High-sensitivity CRP is more sensitive than standard CRP, helping detect low-level inflammation that might not be visible with other tests. It’s often used in heart disease risk assessment or monitoring autoimmune conditions.
What does a normal CRP level mean?
A normal result doesn’t mean no inflammation exists—it means your body’s response is within typical ranges for your health status. Doctors interpret results alongside symptoms and other tests.
Can I eat or drink before this test?
You may eat and drink normally unless your doctor specifies otherwise. Avoiding alcohol or certain medications (like NSAIDs) for 24 hours before testing may improve accuracy.
  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