C-reactive protein (CRP) by nephelometry (serum/plasma)
This blood test measures the level of C-reactive protein, a protein produced by the liver in response to inflammation or infection.
["CRP helps track inflammation in your body."]
Key facts at a glance
- LOINC
- 81142-2
- Short code
- PTPN22 c.1858C>T Bld/T Ql
- Synonyms
- PTPN22 c.1858C>T Bld/T Ql
- Category
- coagulation
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- molgen
- CPT
- 85610
- SNOMED
- 396252006
- 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 arthritis, heart disease, or infections, or evaluate responses to treatments. It can also help assess risk for certain health issues, such as heart disease or autoimmune disorders.
What Does a High or Low CRP Level Mean?
Elevated CRP levels often indicate inflammation, which can be linked to infections, injuries, or inflammatory diseases. Very high levels may suggest severe conditions like sepsis or autoimmune disorders. Low levels usually mean minimal inflammation, but this can vary depending on your overall health and medical history.
How Is the CRP Test Performed?
A small blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab where it is analyzed using nephelometry, a method that measures how much light is scattered by the protein in your blood sample.
What Should You Do Before the Test?
To get the most accurate results, avoid strenuous exercise or consuming very large amounts of red meat, alcohol, or fatty foods 24 hours before your test. If you are on certain medications, like nonsteroidal anti-inflammatory drugs (NSAIDs), inform your healthcare provider before the test.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
CRP is a useful marker for identifying and monitoring inflammation, but it is not definitive on its own. It is often used alongside other tests and clinical evaluations to provide a clearer picture of your health status, especially in diagnosing and managing chronic inflammatory conditions or infections.
Short name
CRP
Frequently asked questions
What does CRP measure exactly?
Can CRP levels change based on diet or lifestyle?
Is CRP the same as a white blood cell count?
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