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C-reactive protein (CRP) by nephelometry

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

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

Quick summary

["CRP helps identify and monitor inflammation, often used to check for infections or other health conditions."]

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

Key facts at a glance

LOINC
18578-5
Short code
J Pnt ST Amp+80ms L-V5
Synonyms
J Pnt ST Amp+80ms L-V5
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 Is This Test Done?

Your healthcare provider may order this test to check for signs of inflammation, monitor chronic conditions like arthritis or heart disease, or evaluate responses to treatments. It can also help diagnose infections, such as pneumonia or sepsis, or assess risks for conditions like heart attacks or kidney disease.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it’s a blood draw, but confirm with your provider. Avoid strenuous activity or excessive stress on the day of testing.

How the Test Works

A small sample of blood is drawn from a vein in your arm. The lab then uses a nephelometry method to measure CRP levels, which is compared to a reference range to determine results.

What the Results Mean

Results are reported in milligrams per liter (mg/L). Higher-than-normal levels may indicate inflammation, infection, or other underlying health issues. Your provider will interpret results in the context of your medical history and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Neph)

Frequently asked questions

What causes CRP levels to be high?
CRP levels can rise due to infections (like flu or urinary tract infections), injuries, surgeries, or certain medical conditions such as rheumatoid arthritis, lupus, or heart disease. Stress, smoking, or certain medications may also temporarily affect CRP levels.
How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on lab processing times. Your provider will contact you once they’re ready to discuss findings.
Can lifestyle changes affect CRP levels?
Yes, lifestyle factors like diet, exercise, smoking, and stress can influence CRP levels. Reducing inflammation through healthy eating, regular physical activity, and avoiding smoking may help lower CRP levels over time.
  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