Serum/plasma concentration of C-reactive protein (CRP) measured by nephelometry
This test measures the level of C-reactive protein, a protein produced by your liver in response to inflammation or infection.
["CRP helps track inflammation in your body, often used to check for infections or other health conditions causing swelling."]
Key facts at a glance
- LOINC
- 110262-3
- Short code
- C4
- Synonyms
- C4 Msmt SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top vacutainer tube
- Units
- N/A
- Ref low
- 16
- Ref high
- 47
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–999 years
- Method
- Immunoturbidimetric assay
- CPT
- 86160
- SNOMED
- 44778000
- Specimen volume
- 1.0 mL serum (minimum 0.5 mL)
- Stability
- Room temperature: 2 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 100
- Icterus max
- 25
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test to monitor conditions like infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., rheumatoid arthritis), or to check for signs of inflammation after surgery or injury. It can also help evaluate heart disease risk or response to treatment.
What Does a High or Low CRP Level Mean?
Elevated CRP levels often indicate inflammation, but they don’t always pinpoint the exact cause. High levels may signal infections, autoimmune diseases, or other health issues. Very low levels might suggest no active inflammation, but they don’t rule out all causes.
How Is the Test Performed?
A blood sample is taken from a vein in your arm. The blood is sent to a lab where it’s analyzed using a nephelometry method to measure CRP levels precisely.
What Are Common Results and Next Steps?
Results are typically reported in milligrams per liter (mg/L). If your CRP is elevated, your provider may recommend further testing (e.g., blood cultures, imaging) or adjust treatments to address the underlying cause.
Reference range
Adult: 16-47 mg/dL (0.16-0.47 g/L). Pediatric reference ranges vary by age; consult laboratory-specific reference intervals for patients under 18 years.N/A
No special patient preparation required. Fasting is not necessary. Specimen collection should occur prior to administration of blood products or complement-modulating therapies when clinically feasible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
CRP is a useful marker for inflammation but isn’t definitive on its own. It’s often used alongside other tests (e.g., blood cultures, imaging) to guide diagnosis and treatment decisions.
Short name
CRP (Nephelometry)
Frequently asked questions
What does a CRP test measure?
How soon after an injury or illness will CRP levels change?
Can CRP levels be affected by medications?
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