C-reactive protein (CRP) by nephelometry (serum/plasma)
This test measures the level of C-reactive protein, a protein produced by the liver in response to inflammation in your body.
["CRP helps doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]
Key facts at a glance
- LOINC
- 17112-4
- Short code
- CD120A
- Synonyms
- CD120A Cells NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender-top) tube for whole blood flow cytometry
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry
- CPT
- 86359
- SNOMED
- 399007007
- Specimen volume
- 3-5 mL whole blood; minimum 1 mL for pediatric samples
- Stability
- Maintain at room temperature (18-25°C); analyze within 24-48 hours of collection for optimal cell viability. Do not refrigerate or freeze.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order a CRP test to check for signs of inflammation. This can help diagnose conditions like infections (such as pneumonia or appendicitis), monitor chronic diseases (like rheumatoid arthritis or lupus), or evaluate how well you’re healing after surgery or an injury. It can also be used to screen for certain heart conditions or to monitor treatment responses.
What to Expect Before the Test
No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, similar to other blood tests. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
CRP levels can vary depending on your health status. Higher than normal levels often indicate inflammation, but they can also be influenced by factors like recent illness, infection, or certain medications. Your provider will interpret the results in the context of your overall health and medical history.
Common Conditions Monitored
CRP is commonly used to monitor conditions such as autoimmune diseases (e.g., rheumatoid arthritis), infections, heart disease risk, and post-surgical healing. It can also help track responses to treatments like steroids or disease-modifying therapies.
Reference range
Reference ranges vary by laboratory and reporting method; results typically expressed as percentage of lymphocytes or absolute count (cells/μL). Consult laboratory-specific reference intervals for interpretation.N/A
No special preparation required. Inform the laboratory of any recent immunosuppressive therapy, corticosteroid use, or chemotherapy as these may affect lymphocyte subset counts.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CRP (NONE)
Frequently asked questions
What Does a High CRP Level Indicate?
What Does a Low CRP Level Indicate?
How Often Should I Get 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