C-reactive protein (CRP) concentration in serum/plasma
This test measures the level of C-reactive protein, a substance produced by the liver in response to inflammation in your body.
["CRP helps doctors assess inflammation, which can signal infections, injuries, or other health conditions."]
Key facts at a glance
- LOINC
- 19167-6
- Short code
- CEA
- Synonyms
- CEA SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube; plasma may be collected in lithium heparin or EDTA tubes
- Units
- N/A
- Ref low
- 0
- Ref high
- 3
- Critical range
- — – 10 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (chemiluminescent or electrochemiluminescent immunoassay)
- CPT
- 82378
- SNOMED
- 829290005
- Specimen volume
- 1-2 mL of serum or plasma
- Stability
- Room temperature: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 3 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 300
- Icterus max
- 25
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test to check for signs of inflammation, monitor conditions like arthritis, heart disease, or infections, or evaluate how your body is responding to treatment for certain illnesses.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it involves drawing blood from a vein. If you’re taking blood from a fingerstick, fasting isn’t required.
What Happens During the Test?
A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it’s usually over quickly. The blood sample is then sent to a lab for analysis.
What Are Possible Results?
Results are reported in milligrams per liter (mg/L) or micrograms per milliliter (µg/mL). Higher levels may indicate inflammation, while lower levels suggest reduced inflammation. Your results will be interpreted by your doctor based on your health history and symptoms.
Reference range
Non-smokers: <3.0 ng/mL (<3.0 ug/L); Smokers: <5.0 ng/mL (<5.0 ug/L). Reference values may vary by laboratory and assay methodology.N/A
No fasting required. No special patient preparation needed. Recent smoking status should be noted as it can elevate CEA levels. Inform the laboratory if the patient is a smoker.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CRP (Serum/Plasma)
Frequently asked questions
What does an elevated CRP level mean?
What if my CRP level is normal?
How often should I get this test?
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