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

Quick summary

["CRP helps doctors assess 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
77492-7
Short code
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Synonyms
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Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
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 rheumatoid arthritis or heart disease, or evaluate your response to treatment. It can also help identify infections or other inflammatory processes in your body.

What Does a High or Low CRP Level Mean?

Elevated CRP levels often indicate inflammation or infection, but they can also be influenced by factors like stress, certain medications, or obesity. Low levels may suggest reduced inflammation, but they don’t always mean you’re healthy.

Sample Collection and Preparation

A blood sample is taken from a vein, usually in your arm. The blood is processed to separate plasma, which is then analyzed for CRP levels using a specialized nephelometry method.

Common Conditions Monitored

CRP is commonly used to monitor conditions such as cardiovascular disease, autoimmune disorders (e.g., lupus, rheumatoid arthritis), and to guide decisions about treatments like antibiotics or steroids.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP is a non-specific marker of systemic inflammation. While it doesn’t pinpoint the exact cause of inflammation, it provides a broad indicator useful for diagnosis, treatment planning, and disease management. Elevated levels may prompt further testing or adjustments in care.

Short name

CRP (Plasma)

Frequently asked questions

What triggers CRP levels to rise?
CRP levels can rise due to infections (like pneumonia or urinary tract infections), injuries, surgeries, or certain medical conditions such as autoimmune diseases. Stress, smoking, obesity, and some medications can also affect CRP levels.
How often should I get this test?
The frequency depends on your medical condition and treatment plan. Your healthcare provider will determine how often you need this test, whether it’s routine monitoring or part of a specific evaluation.
Can lifestyle changes affect CRP levels?
Yes, lifestyle factors like diet, exercise, smoking, and managing chronic conditions (e.g., diabetes, hypertension) can influence CRP levels. Small, sustainable changes often lead to better overall health and may help lower 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