C-reactive protein (CRP) by nephelometry
This test measures the level of C-reactive protein, a protein produced by your liver in response to inflammation.
["CRP helps doctors assess inflammation in your body."]
Key facts at a glance
- LOINC
- 5520-2
- Short code
- Deprecated CD66e WBC-aCnc
- Synonyms
- Deprecated CD66e WBC-aCnc
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 4.5
- Ref high
- 11
- Critical range
- 2 N/A – 30 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85004
- SNOMED
- 900000000000003002
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order a CRP test to check for signs of inflammation, monitor conditions like infections, autoimmune diseases, or heart disease, or evaluate how well a treatment is working. It can also be used as part of a general health screening or to monitor chronic conditions.
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 your blood is drawn from a vein (venipuncture). If a fingerstick is used, no fasting is required. Tell your provider about any medications you’re taking, as some may affect results.
What Happens During the Test?
A healthcare professional will collect a small sample of blood, either from a vein in your arm or by pricking your finger. The blood is then sent to a lab where it’s analyzed using nephelometry, a method that measures how much light is scattered by the CRP protein in your sample.
What Are the Results Measured Against?
CRP results are typically reported in milligrams per liter (mg/L). Higher levels may indicate inflammation, while lower levels suggest reduced inflammation. However, reference ranges can vary by lab and individual health status.
Reference range
Adult: 4.5-11.0 x 10^9/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated CRP levels often signal inflammation, which can be caused by infections (like pneumonia or urinary tract infections), autoimmune diseases (such as rheumatoid arthritis or lupus), heart disease, or other inflammatory conditions. It’s not specific to any single condition but is useful for monitoring overall inflammatory activity. Low CRP levels may indicate a lack of inflammation, but they don’t rule out other causes of symptoms.
Short name
CRP (Nephelometry)
Frequently asked questions
How Long Does It Take to Get Results?
Can I Eat or Drink Before the Test?
Does This Test Have Any Side Effects?
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 16, 2026. · Read our editorial policy