C-reactive protein (CRP) by nephelometry (serum/plasma)
This test measures the level of C-reactive protein, a protein produced by your liver in response to inflammation or infection.
["CRP helps doctors assess inflammation in your body."]
Key facts at a glance
- LOINC
- 7188-6
- Short code
- CATFHR
- Synonyms
- Catfish BasoBnd Ab Qn
- Category
- chemistry
- Sample
- whole-blood
- Container
- Sodium heparin (green-top) or EDTA (lavender-top) tube for whole blood basophil assays
- Units
- N/A
- Ref low
- 0
- Ref high
- 10
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 2 years
- Method
- Basophil histamine release assay (flow cytometry or fluorometric method)
- CPT
- 86003
- SNOMED
- 428523007
- Specimen volume
- 5-10 mL whole blood
- Stability
- Sample must be processed within 4-6 hours of collection; do not refrigerate. Maintain at room temperature (18-25°C) during transport to laboratory.
- Hemolysis max
- 100
- Lipemia max
- 200
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test to check for signs of inflammation, infection, or other health conditions like heart disease, autoimmune disorders, or kidney problems. It can also be used to monitor treatment progress for conditions causing chronic inflammation.
What Does a High CRP Level Mean?
Elevated CRP levels often indicate inflammation, which can be caused by infections (like pneumonia or urinary tract infections), injuries, or inflammatory diseases (like rheumatoid arthritis). However, CRP alone doesn’t diagnose a specific condition—it’s usually one piece of a larger picture.
What Does a Low CRP Level Mean?
Low CRP levels typically suggest minimal inflammation. However, very low levels might raise concerns if inflammation is expected (e.g., after surgery or treatment for an infection). Your provider will interpret results in the context of your medical history and other tests.
How Is This Test Performed?
A small blood sample is drawn from a vein in your arm. The blood is sent to a lab where it’s analyzed using nephelometry, a method that measures how much light is scattered by proteins in the sample. Results are usually available within a few hours to a day.
Reference range
Negative: <10% histamine release above baseline. Positive: ≥10% histamine release above baseline. Results interpreted in context of clinical history and other allergy test findings.N/A
No special preparation required. Patients should continue their usual medications unless otherwise directed by their physician. Antihistamine use generally does not interfere with basophil activation or histamine release assays as the test measures direct cellular response.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: CRP as a Marker of Inflammation
Short name
CRP
Frequently asked questions
Why might my CRP test be ordered?
What if my CRP level is normal but I still feel unwell?
Can CRP levels change with diet or exercise?
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