C-reactive protein (CRP) concentration in serum/plasma
This test measures the level of C-reactive protein, a protein produced by the liver in response to inflammation in your body.
["CRP helps doctors assess inflammation, often used to monitor conditions like infections or autoimmune diseases."]
Key facts at a glance
- LOINC
- 111866-0
- Short code
- Reached area Endscpy
- Synonyms
- Reached area Endscpy
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- endoscopy
- 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 CRP tested?
Doctors may order CRP tests to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or evaluate responses to treatments. It can also help identify infections or other inflammatory processes in the body.
What does a CRP test involve?
A small blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab for analysis. CRP levels are measured using an immunoassay method, which detects the protein in your blood.
What might affect CRP levels?
Several factors can influence CRP levels, including infections (like colds or flu), injuries, certain medications, smoking, and chronic health conditions. Stress and physical activity can also temporarily affect results.
What do CRP results mean?
Higher-than-normal CRP levels often indicate inflammation. While elevated CRP can signal infections or autoimmune diseases, it doesn’t always pinpoint the exact cause. Doctors use CRP results alongside other tests and symptoms to guide diagnosis and treatment.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
CRP is a key marker for identifying and monitoring inflammation. It’s widely used in both acute settings (e.g., sepsis) and chronic conditions (e.g., cardiovascular disease risk assessment). While not specific to any single disease, CRP helps guide decisions about further testing or treatment adjustments.
Short name
CRP
Frequently asked questions
What does a high CRP level mean?
A low CRP level usually means there is little to no inflammation detected in your blood. However, it doesn’t rule out other conditions that might not cause inflammation. Your doctor will consider the full clinical picture when interpreting results.
Yes, CRP levels can fluctuate. They may rise quickly in response to infections or injuries and can take time to return to normal. Chronic conditions may also cause steady, lower-level inflammation that can be monitored over time.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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