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C-reactive protein (mass concentration) in serum/plasma

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

This test measures the amount 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 or autoimmune diseases."]

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

Key facts at a glance

LOINC
27365-6
Short code
Kappa LC Ur-mCnc
Synonyms
Kappa LC Ur-mCnc
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
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, monitor chronic conditions, or evaluate symptoms like fever, joint pain, or unexplained fatigue. It can also help guide treatment decisions for infections, heart disease, or other inflammatory disorders.

What to Expect During the Test

A blood sample is taken from a vein, usually in your arm. You may feel a slight pinch, but it’s quick and typically painless. No special preparation is usually needed, though your provider may advise fasting if the test is part of a broader metabolic evaluation.

Common Uses and Conditions

CRP is often used to monitor conditions like rheumatoid arthritis, lupus, or other autoimmune diseases. It may also help diagnose or track infections, heart disease risk, or responses to treatments like steroids.

Factors That Can Affect Results

Infections, injuries, or illnesses can raise CRP levels. Certain medications (like steroids) or smoking may also influence results. Stress, recent exercise, or pregnancy can sometimes affect readings, so it’s important to discuss your medical history with your provider.

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 high CRP level mean?
A high CRP level often signals inflammation, which can be caused by infections, autoimmune diseases, or other inflammatory processes. However, elevated CRP alone doesn’t always indicate a specific condition—it’s usually one piece of a larger picture evaluated alongside other tests and symptoms.
What does a low CRP level mean?
A low CRP level usually suggests minimal inflammation, but it can also occur in healthy individuals or those with controlled inflammatory conditions. Always discuss results with your healthcare provider, as they’ll consider your overall health and medical history.
Can CRP levels change over time?
Yes, CRP levels can fluctuate based on your health status, treatments, or underlying conditions. Regular monitoring may be needed to track changes, especially if you have chronic conditions like arthritis or heart disease.
  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