C-reactive protein (CRP) mass 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
- 6908-8
- Short code
- C4BF
- Synonyms
- C4 Fld-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or serum separator tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunonephelometry
- CPT
- 86160
- SNOMED
- 1153314008
- Specimen volume
- 1-2 mL of serum
- Stability
- Stable for 8 hours at room temperature; 2 days at 2-8°C; 2 months frozen at -20°C
- Hemolysis max
- 100
- Lipemia max
- 200
- Icterus max
- 40
- 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 arthritis or heart disease, or evaluate symptoms such as fever, joint pain, or unexplained fatigue. It can also help guide treatment decisions for infections or inflammatory disorders.
What Does a High or Low CRP Level Mean?
A higher than normal CRP level often indicates inflammation or infection. A low level suggests minimal inflammation, but it doesn’t rule out other conditions. Your results will be interpreted by your healthcare provider based on your overall health and symptoms.
Sample Collection and Preparation
A blood sample is drawn from a vein, usually in your arm. The blood is collected in a tube that separates serum or plasma from blood cells. This sample is then sent to a lab for testing.
Common Conditions Monitored
CRP is commonly used to monitor conditions like rheumatoid arthritis, lupus, heart disease, infections (e.g., pneumonia, sepsis), and other inflammatory or autoimmune diseases. It can also help track response to treatments.
Reference range
10-40 mg/dL (serum reference range; body fluid values interpreted in clinical context)N/A
No special patient preparation required. Fasting is not necessary.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CRP (Serum/Plasma)
Frequently asked questions
What Does CRP Measure?
How Often Should CRP Be Checked?
Can CRP Levels Change Without a Clear Cause?
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 15, 2026. · Read our editorial policy