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C-reactive protein (CRP) concentration

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

This test measures the level of C-reactive protein in your blood, a substance produced by your liver in response to inflammation.

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
36087-5
Short code
CT Head Ltd
Synonyms
CT Head Ltd
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

What CRP Measures

CRP is a protein that rises when your body is fighting inflammation. It’s not specific to any one condition but can signal widespread inflammation, which may be due to infections, injuries, or certain diseases like arthritis or heart disease.

Why It’s 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 fatigue that might suggest an underlying issue.

Common Uses

CRP is often used alongside other tests to help diagnose conditions like sepsis, rheumatoid arthritis, or heart disease. It can also be used to track how well treatment is working for inflammatory conditions.

What to Expect

A small blood sample is taken from a vein, usually in your arm. The process is quick and usually painless, though you might feel a slight pinch. Results are typically ready within a few days.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP

Frequently asked questions

How high or low CRP levels might be interpreted depends on your overall health, symptoms, and other test results. High CRP levels can indicate inflammation, while very low levels might suggest reduced immune response or certain medical conditions.
A CRP test alone doesn’t diagnose a specific condition. It’s often used as part of a broader evaluation to guide treatment decisions.
What causes CRP levels to change?
CRP levels can rise due to infections (like pneumonia or urinary tract infections), injuries, surgeries, or certain medications. They may also be elevated in conditions like rheumatoid arthritis, lupus, or heart disease. Stress, smoking, and obesity can also influence CRP levels.
How often should I get a CRP test?
Your doctor will determine how often you need a CRP test based on your health history, symptoms, and treatment plan. Regular monitoring may be recommended if you have chronic inflammatory conditions or risk factors for 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