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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, a protein produced by your liver in response to inflammation or infection.

Quick summary

["CRP helps doctors assess inflammation, track infections, or monitor conditions like autoimmune diseases."]

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

Key facts at a glance

LOINC
9690-9
Short code
Cr Spec-mCnc
Synonyms
Cr Spec-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 chronic conditions like arthritis or heart disease, or evaluate responses to treatments. It’s also used to detect infections, such as pneumonia or sepsis, especially in people with weakened immune systems.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Higher than normal levels may indicate inflammation, infection, or other health issues. Lower levels might suggest no active inflammation. Your provider will interpret results in the context of your medical history and symptoms.

Common Conditions Monitored

CRP is often used alongside other tests to monitor conditions like rheumatoid arthritis, lupus, heart disease, or infections. It can also help guide decisions about starting or stopping certain 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 high CRP level mean?
A high CRP level often signals inflammation or infection, but it can also appear in people without symptoms. Your provider will consider other factors, like symptoms, medical history, and test results, to understand what’s causing it.
Can I eat or drink before this test?
You can eat and drink normally before this test unless your provider gives specific instructions. Blood tests don’t require fasting unless they’re for other substances like cholesterol or glucose.
How often is CRP tested?
The frequency depends on your health condition. Some people get CRP tested monthly, yearly, or only when symptoms or other test results suggest inflammation is present.
  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