C-reactive protein, mass concentration (serum/plasma)
This test measures the level of C-reactive protein, a protein produced by the liver in response to inflammation or infection in your body.
["CRP helps doctors assess inflammation and guide treatment for conditions like infections, autoimmune diseases, or after surgery."]
Key facts at a glance
- LOINC
- 12515-3
- Short code
- CEABF
- Synonyms
- CEA Fld-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or SST (Serum Separator Tube)
- Units
- N/A
- Ref low
- 0
- Ref high
- 3
- Critical range
- — – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Chemiluminescent Immunoassay (CLIA) / Electrochemiluminescence Immunoassay (ECLIA)
- CPT
- 82378
- SNOMED
- 82934-1
- Specimen volume
- 1.0-2.0 mL of serum
- 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
- 500
- 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 chronic conditions like arthritis or heart disease, or evaluate responses to treatments. It can also help identify infections or determine if your body is reacting to an injury or illness.
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’s done on an empty stomach, but this is rare for CRP. Bring any medications you’re taking to your appointment.
How the Test Works
A small blood sample is taken from a vein in your arm. The blood is sent to a lab, where it’s analyzed to measure CRP levels using a sensitive detection method.
What the Results Mean
Higher-than-normal CRP levels may indicate inflammation, infections, or other health concerns. Lower levels suggest reduced inflammation. Your results will be compared to standard reference ranges provided by your lab.
Reference range
Non-smokers: <3.0 ng/mL; Smokers: <5.0 ng/mL. Reference values vary by laboratory methodology and patient population.N/A
No fasting required. However, patients should avoid smoking for 24 hours prior to specimen collection as smoking can elevate CEA levels. Inform the laboratory of any recent diagnostic procedures, surgeries, or biopsies.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: CRP is a key marker for inflammation, often used alongside other tests to diagnose or monitor conditions like rheumatoid arthritis, sepsis, or cardiovascular disease. Elevated levels may prompt further testing or adjustments to treatment plans.
Short name
CRP (Serum/Plasma)
Frequently asked questions
What causes CRP levels to change?
How long does it take to get results?
Can diet or exercise affect 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 15, 2026. · Read our editorial policy