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C-Reactive Protein (CRP) by Immunoassay, Plasma

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of C-reactive protein in your blood plasma, a protein produced by the liver in response to inflammation.

Quick summary

["CRP helps identify and monitor inflammation in your body."]

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

Key facts at a glance

LOINC
35648-5
Short code
CRP Quint SerPl Qn HS
Synonyms
CRP Quint SerPl Qn HS
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
3
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
high-sensitivity
CPT
86140
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 conditions like infections, autoimmune diseases, or after surgery. It can also help assess risk for heart disease or other inflammatory conditions.

What Does a High or Low CRP Level Mean?

A higher CRP level often indicates inflammation, which can be linked to infections, injuries, or diseases like rheumatoid arthritis or heart disease. A very low level may suggest no active inflammation, but it’s not always definitive.

How Is the Test Performed?

A blood sample is taken from a vein in your arm. The plasma portion is then analyzed using an immunoassay method to measure CRP levels.

What Are Common Uses?

This test is commonly used to screen for inflammation, monitor chronic conditions, or evaluate response to treatment for inflammatory diseases.

Reference range

Normal: <3.0 mg/LN/A

Specimen: serum

No special preparation required. CRP may be affected by acute illness.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP Plasma

Frequently asked questions

What does a CRP test tell me about my health?
A CRP test helps your healthcare provider assess whether inflammation is present in your body, which can signal potential infections, autoimmune diseases, or other health concerns. It doesn’t diagnose a specific condition but may prompt further testing if needed.
How soon will I get my results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing schedule. Your provider will discuss the meaning of your results with you.
Can I eat or drink before this test?
You can eat and drink normally before this test, as it doesn’t require fasting. However, follow any specific instructions your provider gives you for your particular situation.
  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