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C-reactive protein (serum/plasma) concentration

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

This test measures the level of C-reactive protein, a protein made by your liver in response to inflammation in the 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
26666-8
Short code
C trach H Ab Ser Ql
Synonyms
C trach H Ab Ser Ql
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 rheumatoid arthritis or lupus, or evaluate recovery from an illness or procedure. It can also help determine if an infection is present or worsening.

What Does a High or Low Level Mean?

Elevated CRP levels often indicate inflammation or infection, while very low levels may suggest no active inflammation. However, results alone don’t diagnose a specific condition—your doctor will consider your full medical picture.

How Is the Test Performed?

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

What Are Common Uses?

Common reasons include monitoring chronic inflammatory diseases, assessing risk for heart disease, evaluating fever of unknown origin, or checking for signs of infection in people with weakened immune systems.

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 tell me about my health?
It tells your doctor whether inflammation is active in your body but doesn’t pinpoint the exact cause. It’s often used alongside other tests to help plan care.
How often should I get this test?
Your doctor will determine how often based on your medical needs—some people get it yearly, while others may need it more frequently if they have ongoing health concerns.
Can I prepare for this test?
No special preparation is needed, but avoid heavy meals or strenuous activity before the blood draw if instructed by your provider.
  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