Serum or plasma mass concentration of C-reactive protein (CRP)
This test measures the amount of C-reactive protein in your blood, a protein produced by your liver in response to inflammation.
["CRP helps doctors assess inflammation in your body."]
Key facts at a glance
- LOINC
- 4503-9
- Short code
- C4BP
- Synonyms
- C4b BP SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or plain red-top tube
- Units
- N/A
- Ref low
- 0.18
- Ref high
- 0.55
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Enzyme-linked immunosorbent assay (ELISA) or nephelometry
- Specimen volume
- 1 mL serum
- Stability
- Stable for 8 hours at room temperature, 2 days at 2–8°C, or 3 months at -20°C
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
What Is C-Reactive Protein (CRP)?
C-reactive protein (CRP) is a marker your immune system produces when tissues are damaged or inflamed. It’s often measured to check for infections, autoimmune conditions, or other inflammatory processes. CRP isn’t specific to any single condition—it’s a general indicator of your body’s inflammatory response.
Why Might You Need This Test?
Your doctor may order CRP testing to monitor chronic conditions like arthritis, heart disease, or inflammatory bowel disease. It can also help track how well treatments are working or detect new inflammation after surgery, injury, or illness. In some cases, it’s used as part of a broader screening for cardiovascular risk.
How Is the Test Performed?
A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure CRP levels. The test is quick and typically done as part of a routine blood draw.
What Do Results Mean?
Results are usually reported in milligrams per liter (mg/L). Higher levels may suggest inflammation, infection, or other underlying issues, but interpretation depends on your overall health and symptoms. Your doctor will discuss the results with you.
Reference range
0.18–0.55 g/L (varies by laboratory and assay method)N/A
No special patient preparation required. Specimen should be collected before any immunosuppressive therapy when possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CRP Level
Frequently asked questions
How often do I need this test?
What happens if my CRP levels are high?
Can I influence my CRP levels?
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