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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 in your blood, a protein produced by your liver in response to inflammation.

Quick summary

["CRP helps track 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
33135-5
Short code
GA from TC.Nimrod86
Synonyms
GA from TC.Nimrod86
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-estimated-from-tc-nimrod
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 or assess risks for conditions like heart disease.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours if your blood is drawn early in the morning. Wear a loose shirt for easy access.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a small pinch, but it usually doesn’t cause significant discomfort. The blood is then sent to a lab for analysis.

What the Results Mean

Results are reported in milligrams per liter (mg/L). Higher levels may indicate inflammation, infection, or other health issues, while lower levels may suggest no active inflammation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP’s Role in Health

Short name

CRP (Nephelometry)

Frequently asked questions

What Are Common Causes of Elevated CRP?
Elevated CRP can be caused by infections (like pneumonia or urinary tract infections), injuries, surgeries, or certain autoimmune diseases (e.g., rheumatoid arthritis). Chronic conditions like heart disease or diabetes may also lead to higher baseline CRP levels.
What Are Common Causes of Low CRP?
Low CRP levels are often normal and may indicate no active inflammation. However, very low levels could sometimes suggest an underlying condition that needs further evaluation, especially if symptoms persist.
How Often Should I Get This Test?
Your provider will determine how often you need this test based on your health status, symptoms, and treatment plan. Regular monitoring may be recommended for chronic conditions like heart disease or arthritis.
  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