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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 protein produced by your liver in response to inflammation.

Quick summary

["CRP helps identify inflammation in your body, often used to monitor conditions like infections, autoimmune diseases, or heart disease."]

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

Key facts at a glance

LOINC
38767-0
Short code
CT IAC-R
Synonyms
CT IAC-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 doctor may order a CRP test to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or evaluate symptoms such as fever, joint pain, or swelling. It can also help assess risk for heart disease or guide treatment decisions for infections.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually causes only mild discomfort. If you’re on blood thinners or have a history of bleeding issues, let your doctor know.

What the Results Mean

CRP levels can vary based on health status, age, and other factors. Higher than normal levels may suggest inflammation, but they don’t always pinpoint the exact cause. Your doctor will interpret results in the context of your medical history and other tests.

Common Conditions Monitored

CRP is often used to track conditions like infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., rheumatoid arthritis, lupus), or inflammatory heart disease. It may also help evaluate response to treatment or detect early signs of complications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

CRP

Frequently asked questions

What does a high CRP level mean?
A high CRP level often indicates inflammation in your body, which can be caused by infections, injuries, or autoimmune diseases. However, it doesn’t always show the exact cause, so your doctor will consider other factors. Chronic, low-level CRP may signal long-term inflammation linked to conditions like heart disease or certain cancers.
What does a low CRP level mean?
Low CRP levels usually mean there’s little to no inflammation detected in this test. However, they don’t rule out inflammation entirely—some conditions may not raise CRP. Your doctor may use CRP alongside other tests to get a full picture.
Can CRP levels change with diet or exercise?
Yes, lifestyle factors like diet, exercise, and smoking can influence CRP levels. Reducing inflammation through healthy habits may lower CRP, but results depend on overall health and medical conditions.
  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