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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 your liver in response to inflammation or infection in your body.

Quick summary

["CRP helps doctors assess inflammation and track 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
59421-8
Short code
N men sg A+B+C+W135+Y Ag CSF Ql LA
Synonyms
N men sg A+B+C+W135+Y Ag CSF Ql LA
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
la
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may order CRP testing to monitor chronic conditions such as rheumatoid arthritis, heart disease, or inflammatory bowel disease. It can also help detect infections, evaluate response to treatment, or check for signs of inflammation after surgery or injury.

What to Expect Before the Test

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

What the Results Mean

Higher CRP levels often indicate inflammation, but they can also rise with fever, stress, or certain medications. Your results will be compared to a general reference range provided by your lab.

Common Conditions Monitored

CRP is used to monitor conditions like infections (e.g., pneumonia), autoimmune diseases (e.g., lupus), or to check for signs of heart attack or stroke risk in some patients.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP’s Role in Healthcare

Short name

CRP (Serum/Plasma)

Frequently asked questions

How often will I need this test?
The frequency depends on your condition. Some patients need CRP checked monthly, while others may only need it once or twice a year. Your doctor will guide you on timing based on your treatment plan.
Can diet or exercise affect CRP levels?
Yes, lifestyle factors like diet, exercise, and weight can influence CRP levels. Reducing inflammation through healthy eating, regular activity, and avoiding smoking may lower CRP levels over time.
What if my CRP is elevated?
If your CRP is elevated, your doctor may recommend further testing or adjustments to your treatment plan. This could include treating an infection, managing an autoimmune condition, or exploring lifestyle changes to reduce inflammation.
  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