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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, a protein produced by the liver in response to inflammation in your body.

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
30619-1
Short code
CT SIJ
Synonyms
CT SIJ
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 This Test Is Done

Doctors 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 unexplained fatigue. It can also help determine if an infection is present or if your body is overreacting to an injury or illness.

What to Expect Before the Test

No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before the draw if your lab uses a different method, but this is not always required. Your blood will be drawn from a vein, usually in your arm, and you may feel a slight pinch or discomfort for a few seconds.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL). Higher than normal levels may indicate inflammation, infection, or other health issues. Your doctor will interpret results based on your symptoms, medical history, and other tests.

Common Conditions Monitored

CRP is often used to track conditions like cardiovascular disease, inflammatory bowel disease, or to evaluate responses to treatments for autoimmune disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: CRP as a Marker of Inflammation

Short name

CRP Level

Frequently asked questions

What does a high CRP level mean?
A high CRP level often signals inflammation in your body, which can be caused by infections (like pneumonia or urinary tract infections), autoimmune diseases (like rheumatoid arthritis), or other conditions that trigger an immune response. It’s not specific to one illness, so doctors use it alongside other tests to guide diagnosis.
Can CRP levels change over time?
Yes, CRP levels can fluctuate. They may rise quickly in response to acute infections or injuries and then drop once the body heals. Chronic conditions like arthritis may cause steady, lower-level CRP elevation, so monitoring over time helps track disease activity.
Is CRP the same as a white blood cell count?
No, CRP is a protein produced by the liver in response to inflammation, while white blood cell counts measure the number of immune cells in your blood. Both are useful but provide different insights into health.
  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