C-reactive protein (CRP) concentration, measured by nephelometry
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
- 19168-4
- Short code
- CEAPLEURAL
- Synonyms
- CEA Plr-aCnc
- Category
- chemistry
- Sample
- fluid
- Container
- Sterile, leak-proof, screw-cap container (plain or heparinized tube); no anticoagulant preferred unless cell count required
- Units
- N/A
- Ref low
- 0
- Ref high
- 5
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (Chemiluminescent or Electrochemiluminescent)
- CPT
- 82378
- SNOMED
- 104736003
- Specimen volume
- 5-10 mL of pleural fluid
- Stability
- Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 300
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your healthcare provider may order a CRP test to check for signs of inflammation, monitor chronic conditions, or evaluate responses to treatments. It’s sometimes used alongside other tests to help diagnose conditions like infections, heart disease, or certain types of arthritis.
What to Expect Before the Test
No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, similar to other routine blood tests. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
CRP levels can vary depending on your health status. Higher-than-normal levels may indicate inflammation, while lower levels suggest reduced inflammation. Your results will be compared to a reference range specific to your situation, such as whether you have an active illness or chronic condition.
Common Conditions Monitored
CRP is often used to monitor conditions like rheumatoid arthritis, lupus, or other autoimmune diseases. It may also help track infections, heart disease progression, or reactions to treatments like steroids.
Reference range
NCBI: CEA <5 ng/mL (non-smokers <2.5)N/A
No fasting required. Thoracentesis is performed under sterile conditions by a qualified healthcare provider. Local anesthesia is typically administered. Patients should inform their physician of any bleeding disorders or anticoagulant use prior to the procedure.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CRP (Nephelometry)
Frequently asked questions
How often should I get this test?
Can diet or exercise affect CRP levels?
What if my CRP levels are high?
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 17, 2026. · Read our editorial policy