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C-reactive protein (CRP) by nephelometry (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 identify inflammation, often used to monitor conditions like infections or autoimmune diseases."]

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

Key facts at a glance

LOINC
31508-5
Short code
M cap caprip Ab Bld Ql
Synonyms
M cap caprip Ab Bld Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
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 or assess risks for conditions like heart disease.

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, inform your provider beforehand.

What the Results Mean

Higher-than-normal CRP levels may indicate inflammation, infections, or certain diseases. Lower levels suggest reduced inflammation. Your results will be interpreted by your healthcare provider based on your medical history and symptoms.

Common Conditions Monitored

CRP is often used to monitor conditions such as rheumatoid arthritis, lupus, heart disease, or infections like pneumonia or sepsis. It can also guide treatment decisions for conditions like inflammatory bowel disease.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Nephelometry)

Frequently asked questions

How often will I need this test?
Is there any risk or discomfort with this test?
Can I eat or drink before this test?
You can eat and drink normally before the test unless your provider specifies otherwise. No fasting is required for this blood test.
If your CRP levels are high, your provider may investigate further to identify the cause of inflammation, such as infections, autoimmune diseases, or other health issues. If low, it may indicate reduced inflammation, but further evaluation is needed if symptoms persist.
What if my CRP levels are abnormal?
  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