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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 (CRP) in your blood, a protein produced by your liver in response to inflammation.

Quick summary

["CRP helps identify inflammation, which can signal infections, injuries, or other health issues."]

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

Key facts at a glance

LOINC
26231-1
Short code
CT Extr-R
Synonyms
CT Extr-R
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ct
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 a CRP test to check for signs of inflammation in your body. This can help diagnose conditions like infections (such as pneumonia or urinary tract infections), autoimmune diseases (like rheumatoid arthritis), or to monitor treatment progress for conditions that cause chronic inflammation.

What to Expect During the Test

A small blood sample is taken from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The sample is then sent to a lab for analysis.

What the Results Mean

CRP levels can vary widely depending on your health status. Higher than normal levels may indicate inflammation, while lower levels suggest less inflammation. Your results will be interpreted by your healthcare provider in the context of your overall health and medical history.

Common Conditions Monitored

CRP is often used to monitor conditions such as heart disease, infections, and inflammatory diseases. 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

Frequently asked questions

What causes CRP levels to be higher than usual?
CRP levels can rise due to infections (like colds, flu, or urinary tract infections), injuries, surgeries, or certain medical conditions such as autoimmune diseases (like lupus or rheumatoid arthritis). Stress, smoking, and some medications can also affect CRP levels.
How often should I get this test?
The frequency of CRP testing depends on your medical needs. Your healthcare provider will determine how often you need this test based on your symptoms, medical history, and treatment plan.
Can diet or lifestyle changes affect CRP levels?
Yes, lifestyle factors like diet, exercise, smoking, and weight can influence CRP levels. Eating a healthy diet, staying active, and avoiding smoking may help lower inflammation and CRP levels over time.
  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