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

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

This test measures the amount of C-reactive protein in your blood. CRP is a protein produced by your liver in response to inflammation or infection.

Quick summary

["CRP helps doctors assess inflammation, infection, or risk of future health issues like heart disease."]

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

Key facts at a glance

LOINC
5619-2
Short code
Cr Bld-mCnc
Synonyms
Cr Bld-mCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is CRP Used For?

Doctors may order CRP to check for infections (like pneumonia or urinary tract infections), monitor chronic conditions (such as arthritis or heart disease), or evaluate how your body is responding to treatment. It can also help identify risks for conditions like heart attacks or stroke.

How Is the Test Done?

A blood sample is taken from a vein, usually in your arm. The blood is sent to a lab where it is processed to measure CRP levels using a sensitive test method.

What Does a High or Low CRP Level Mean?

High CRP levels often signal inflammation, infection, or autoimmune activity. Low levels may indicate no active inflammation, but they don’t always mean you’re healthy. Your doctor will interpret results in the context of your symptoms and medical history.

Common Causes of Abnormal CRP Levels

Elevated CRP can be caused by infections (bacterial, viral, or fungal), injuries, surgeries, or conditions like rheumatoid arthritis, lupus, or heart disease. Low CRP might be normal, but it can also occur with certain medications or in people with very mild inflammation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CRP

Frequently asked questions

Why might my doctor ask for this test?
Your doctor may order CRP to monitor your condition, check for hidden inflammation, or assess your risk for future health problems like heart disease or certain cancers. It’s often used alongside other tests to guide treatment decisions.
What should I do if my CRP level is high?
If your CRP is high, your doctor may recommend treatments to reduce inflammation (like medications, lifestyle changes, or addressing infections). Follow their advice and report any new symptoms to avoid worsening your condition.
Can diet or exercise affect CRP levels?
Yes! Eating a heart-healthy diet, staying active, and managing stress can help lower CRP levels over time. Avoiding smoking and limiting processed foods may also support better inflammation control.
  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