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C-reactive protein (CRP) by nephelometry

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

This test measures a protein in your blood that rises when your body is responding to inflammation, infection, or injury.

Quick summary

["CRP helps track inflammation levels for conditions like infections, autoimmune diseases, or heart disease."]

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

Key facts at a glance

LOINC
9902-8
Short code
P wave dur L-AVL
Synonyms
P wave dur L-AVL
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
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 It’s Ordered

Your doctor may order this test to monitor inflammation, check for signs of infection, or evaluate conditions like rheumatoid arthritis, heart disease, or after surgery.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on blood thinners, let your doctor know.

What the Results Mean

Higher CRP levels often indicate inflammation, but results alone don’t diagnose a condition. Your doctor will compare them to your symptoms and other tests.

Common Conditions Monitored

This test is used to assess inflammation in conditions like infections (e.g., pneumonia), autoimmune diseases (e.g., lupus), or after procedures (e.g., heart surgery).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (High-Sensitivity)

Frequently asked questions

What causes CRP levels to change?
CRP rises with infections, injuries, or autoimmune activity. It may also increase with stress, certain medications, or pregnancy. It typically returns to normal once the cause resolves.
How soon will I get my results?
Results are usually available within 24–48 hours, depending on your lab. Your doctor will discuss them with you.
Can I lower CRP levels naturally?
Yes! Reducing inflammation may involve diet (e.g., anti-inflammatory foods), exercise, stress management, and avoiding smoking. Always ask your doctor before trying new approaches.
  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