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C-reactive protein (CRP) mass concentration in 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 doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or after injury."]

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

Key facts at a glance

LOINC
4518-7
Short code
Comp Fact D SerPl-mCnc
Synonyms
Comp Fact D SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 CRP testing to check for signs of inflammation. This could be due to suspected infections, conditions like rheumatoid arthritis, heart disease, or to monitor treatment progress for certain illnesses.

What Does a High or Low CRP Level Mean?

Elevated CRP levels often indicate inflammation or infection. Very high levels may suggest severe conditions like sepsis or large tissue damage. Low levels may suggest reduced inflammation, but they don’t always mean you’re healthy.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum or plasma for testing.

What Are Common Uses?

CRP is commonly used to screen for infections, monitor chronic inflammatory diseases, evaluate heart disease risk, and assess response to treatments like steroids or biologics.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CRP plays a critical role in identifying and managing inflammatory conditions. It’s a simple, non-invasive test that helps guide treatment decisions by providing insight into your body’s inflammatory response.

Short name

CRP

Frequently asked questions

How soon will I get my results?
Results are typically available within 1 to 3 business days, depending on lab processing times. Your healthcare provider will discuss the meaning of your results with you.
Is there anything I should do before the test?
Avoid strenuous exercise or taking anti-inflammatory medications (like ibuprofen) 24 hours before the test, as they may affect results. Fasted blood samples are often used but are not required for CRP.
Can CRP levels change with diet or lifestyle?
While diet and lifestyle factors like smoking or obesity can influence inflammation, CRP levels alone don’t directly reflect these factors. Your provider will consider overall health context when interpreting results.
  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