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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. It helps doctors assess whether inflammation is present and monitor conditions like infections, injuries, or autoimmune diseases.

Quick summary

["CRP helps track inflammation and guide treatment decisions."]

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

Key facts at a glance

LOINC
17769-1
Short code
WEEV Ab Titr CSF
Synonyms
WEEV Ab Titr CSF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why CRP Matters in Your Health

CRP is a marker that signals your body’s immune response. High levels often indicate inflammation, which can be caused by infections, injuries, or conditions like arthritis or heart disease. Doctors use CRP to monitor how your body is responding to treatment or to check for early signs of problems.

When You Might Need This Test

Your doctor may order CRP testing if you have symptoms like fever, pain, or swelling, or if you’re being evaluated for conditions like heart disease, infections, or autoimmune disorders. It’s also used during pregnancy to check for signs of infection.

How the Test Works

A small blood sample is taken from your arm. The blood is sent to a lab, where it’s analyzed to measure CRP levels. The test is quick and usually done as part of a routine blood draw.

What to Expect Before the Test

No special preparation is needed for this test. You can eat, drink, or take medications as usual. If you’re on blood thinners, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP (Serum/Plasma)

Frequently asked questions

How high or low CRP levels can affect your care?
High CRP levels may mean your body is fighting infection, experiencing inflammation, or having an autoimmune condition. Low levels might suggest your inflammation is under control, but they can also indicate certain health risks if consistently low.
What does a CRP test tell your doctor?
A CRP test helps your doctor determine if inflammation is present, guide treatment plans, and monitor chronic conditions. It’s especially useful for tracking how well you’re responding to treatments for conditions like arthritis or heart disease.
Can CRP levels change over time?
Yes, CRP levels can fluctuate based on your health status, recent infections, or treatments. Regular testing can help your doctor spot changes early and adjust care as needed.
  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