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C-reactive protein (CRP) 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 surgery."]

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

Key facts at a glance

LOINC
12237-4
Short code
MuV Ag Spec Ql IF
Synonyms
MuV Ag Spec Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 a CRP test to check for signs of inflammation. This 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 a medical procedure.

What Does a High or Low CRP Level Mean?

A high CRP level often indicates inflammation or infection. A low level may suggest no active inflammation, but it doesn’t rule out other conditions. Your results will be interpreted by your doctor based on your full medical history and symptoms.

How Is the Test Performed?

A blood sample is taken from a vein in your arm. The blood is sent to a lab where it’s analyzed to measure CRP levels using an immunoassay method.

What Are Common Causes of Abnormal Results?

High CRP levels can occur with infections, injuries, autoimmune diseases, or certain medications. Low CRP levels may be normal if you have no inflammation, but they can also occur with certain medical conditions or medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum/Plasma)

Frequently asked questions

What does a CRP test measure?
A CRP test measures the concentration of C-reactive protein in your blood, a protein produced by your liver that rises when inflammation is present.
How soon will I get my results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing time. Your doctor will discuss them with you during your follow-up visit.
Can lifestyle changes affect CRP levels?
Yes, lifestyle factors like diet, exercise, and smoking can influence CRP levels. Reducing inflammation through healthy habits may lower CRP, but results vary by individual.
  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