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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 in your blood, a marker often checked to assess inflammation or infection.

Quick summary

["CRP helps doctors track inflammation, infection risk, or response to treatment."]

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

Key facts at a glance

LOINC
5978-2
Short code
PAI2 PPP Chro-aCnc
Synonyms
PAI2 PPP Chro-aCnc
Category
chemistry
Sample
plasma
Container
Lavender-top (EDTA) or Green-top (Heparin)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
chromo
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 This Test Is Done

Your healthcare provider may order this test to monitor conditions like infections (e.g., pneumonia, urinary tract infections), inflammatory diseases (e.g., rheumatoid arthritis), or to check for signs of tissue damage. It can also help evaluate how well you’re responding to treatment for these conditions.

What to Expect Before the Test

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

What the Results Mean

Higher-than-normal CRP levels often indicate inflammation or infection, but results alone don’t diagnose a condition. Your provider will compare results with your symptoms and other tests.

Common Conditions Monitored

Elevated CRP is commonly seen in infections, autoimmune diseases (like lupus or arthritis), heart disease, or after surgery/injury. Low or normal levels suggest minimal inflammation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP (Plasma)

Frequently asked questions

What causes elevated CRP?
Elevated CRP can be caused by infections (bacterial, viral, or fungal), autoimmune diseases (e.g., rheumatoid arthritis, lupus), heart disease, trauma, or certain medications. Chronic conditions like obesity or metabolic syndrome may also lead to slightly elevated levels.
Can CRP levels change with diet or exercise?
Yes, lifestyle factors like diet, exercise, and smoking can influence CRP levels. Reducing inflammation through diet (e.g., Mediterranean diet), regular physical activity, and avoiding smoking may help lower CRP over time.
How often should CRP be checked?
Frequency depends on your health condition. If you have a chronic illness (e.g., arthritis), your provider may recommend periodic testing to monitor progression or treatment effectiveness. Acute infections may require testing only when symptoms arise.
  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