C-reactive protein (CRP) by nephelometry (plasma)
This test measures the level of C-reactive protein in your blood, a protein produced by your liver in response to inflammation.
["CRP helps doctors assess inflammation in your body."]
Key facts at a glance
- LOINC
- 55784-3
- Short code
- WBC nRBC cor # Mar
- Synonyms
- WBC nRBC cor # Mar
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- 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
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- 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 infections, autoimmune diseases, or heart disease, or evaluate responses to treatments. CRP levels can also help determine if you’re at risk for certain health issues over time.
What to Expect Before the Test
No special preparation is needed. You may have a small needle inserted into your arm to draw a blood sample. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
Higher CRP levels often indicate inflammation, but they can also be elevated due to infections, injuries, or other health conditions. Your provider will interpret the results in the context of your overall health and symptoms.
Common Conditions Monitored
This test is commonly used to monitor conditions like rheumatoid arthritis, lupus, heart disease, or infections. It can also help track how well certain treatments are working.
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.
Clinical Significance: CRP is a marker for systemic inflammation. While it doesn’t pinpoint the cause of inflammation, it helps guide decisions about further testing, treatments, or lifestyle changes. Elevated levels may prompt additional evaluations to identify underlying causes.
Short name
CRP (Plasma)
Frequently asked questions
What causes CRP levels to be higher than usual?
How soon will I get my results?
Can I eat or drink before 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 16, 2026. · Read our editorial policy