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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 your body.

Quick summary

["CRP helps doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]

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

Key facts at a glance

LOINC
31295-9
Short code
C trach B IgM Ser-aCnc
Synonyms
C trach B IgM Ser-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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 CRP Matters in Your Health

CRP is a marker of inflammation, meaning it rises when your body is fighting off infections, healing from injury, or dealing with conditions like arthritis or heart disease. High levels may signal an ongoing inflammatory process that could affect other parts of your body.

What Triggers CRP Levels to Change

CRP can increase due to infections (like pneumonia or urinary tract infections), injuries, surgeries, or certain medical conditions such as rheumatoid arthritis, lupus, or heart disease. Stress, smoking, and certain medications may also influence CRP levels.

How CRP Levels Are Interpreted

There’s no single ‘normal’ range for CRP because it varies by individual and health status. Doctors use it as a tool to compare your level to your baseline or to track changes over time, especially if you have a known inflammatory condition.

Common Uses for CRP Testing

Doctors often order CRP tests to check for infections, evaluate heart disease risk, monitor autoimmune diseases, or assess response to treatments like steroids. It can also help guide decisions about when to start or stop certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP’s Role in Diagnosis and Management

Short name

CRP

Frequently asked questions

What causes my CRP levels to be high?
High CRP levels can be caused by infections, chronic inflammation, autoimmune diseases, or other health issues like heart disease. If your doctor notices elevated CRP, they may investigate further to identify the underlying cause, such as through additional tests or lifestyle changes.
Will CRP levels always be high if I have an infection?
Not always. CRP levels rise in response to inflammation, but some infections or conditions may not cause a significant increase. Your doctor will consider CRP alongside other symptoms, test results, and clinical findings to make a diagnosis.
How often should I get a CRP test?
The frequency depends on your health condition and doctor’s recommendations. If you have a chronic condition like arthritis or heart disease, CRP testing may be part of regular monitoring. If you’re healthy, it’s usually only ordered if symptoms suggest inflammation or infection.
  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