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Serum or plasma concentration of C-reactive protein (CRP) measured by nephelometry

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 or infection in your body.

Quick summary

["CRP helps doctors track inflammation or infection and guide treatment decisions."]

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

Key facts at a glance

LOINC
23281-9
Short code
M myc capri Ab Ser Ql CF
Synonyms
M myc capri Ab Ser Ql CF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
comp-fix
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

What Is C-Reactive Protein (CRP) Used For?

CRP is often used to monitor conditions like infections (e.g., pneumonia, urinary tract infections), inflammatory diseases (e.g., rheumatoid arthritis, lupus), or after surgeries or injuries to check for signs of complications. It can also help assess risk for heart disease or other chronic conditions.

How Is CRP Tested?

Your blood sample is drawn and analyzed using a specialized nephelometry method, which detects CRP levels with high precision. Results are typically reported in milligrams per liter (mg/L).

Why Might I Need a CRP Test?

Your healthcare provider may order this test if you have symptoms of inflammation, infection, or if you’re at risk for conditions like heart disease. It can also be used to monitor treatment progress or check for recurring issues.

What Do CRP Results Mean?

CRP levels vary depending on health status. Higher than normal levels may indicate inflammation, infection, or other underlying issues. Your doctor 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 (Nephelometry)

Frequently asked questions

What causes CRP levels to change?
CRP levels rise in response to infections, injuries, or inflammatory diseases. Stress, certain medications, or recent procedures can also temporarily affect results. Avoiding strenuous activity or infections before testing may help get more accurate results.
How soon after a procedure or illness will CRP levels return to normal?
CRP levels typically return to baseline within days to weeks, depending on the cause. For example, after surgery or an infection, levels may drop within a few days, while chronic inflammation could take longer. Your doctor will track changes over time.
Can CRP levels be affected by diet or supplements?
Dietary changes or supplements (e.g., omega-3s, turmeric) may influence inflammation indirectly, but CRP itself isn’t directly affected by diet. Always discuss supplements with your doctor before testing.
  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