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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 the liver in response to inflammation in your body.

Quick summary

["CRP helps identify inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]

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

Key facts at a glance

LOINC
18558-7
Short code
J Pnt ST Amp+60ms L-AVR
Synonyms
J Pnt ST Amp+60ms L-AVR
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
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 check for signs of inflammation. It can help diagnose conditions like infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., rheumatoid arthritis), or to monitor how well you’re healing after surgery or an injury.

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, let your provider know before the test.

What the Results Mean

Higher CRP levels often indicate inflammation, but they can also be affected by factors like fever, stress, or certain medications. Your provider will interpret the results in the context of your overall health and symptoms.

Common Conditions Monitored

Elevated CRP is commonly seen in infections, inflammatory diseases, or after trauma. It’s also used to track response to treatments for conditions like heart disease or cancer.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a marker for systemic inflammation. While it doesn’t pinpoint the cause of inflammation, it helps guide treatment decisions and monitor disease activity in conditions like rheumatoid arthritis, sepsis, or cardiovascular risk assessment.

Short name

CRP Level

Frequently asked questions

What causes CRP levels to be high?
High CRP levels can result from infections (like flu or urinary tract infections), autoimmune diseases (like lupus or arthritis), heart disease, trauma, or certain medications. Stress, obesity, or smoking may also influence results.
How often should I get this test?
Frequency depends on your health condition. Some people get CRP tests regularly (e.g., every few months) to monitor chronic inflammation, while others may need it only during illness or before procedures.
Can diet or lifestyle affect CRP levels?
Yes! A healthy diet (rich in fruits, vegetables, and omega-3s), regular exercise, and avoiding smoking can lower CRP levels. Stress management and weight control also play a role in reducing 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