C-reactive protein (CRP) concentration in 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 identify and monitor inflammation, often used to assess risk for conditions like heart disease or infections."]
Key facts at a glance
- LOINC
- 49139-9
- Short code
- CALIFV-IGM-CSF
- Synonyms
- CEV IgM Titr CSF IF
- Category
- chemistry
- Sample
- csf
- Container
- Sterile CSF collection tube (polypropylene screw-cap tube), tube #4 recommended for serology/infectious disease testing
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- Immunofluorescence (IFA)
- CPT
- 86651
- SNOMED
- 3129009
- Specimen volume
- 1-2 mL of cerebrospinal fluid
- Stability
- Refrigerated (2-8°C): up to 7 days. Frozen (-70°C or below): up to 30 days. Do not freeze at -20°C.
- Hemolysis max
- 200
- TAT
- 24–168 hours
- Order
- routine
What Is C-Reactive Protein?
C-reactive protein (CRP) is a marker your immune system produces when tissues are damaged or inflamed. It’s often checked alongside other blood tests to help doctors understand whether you have an infection, an inflammatory condition, or increased risk for heart problems.
Why Might You Need This Test?
Your doctor may order CRP testing if you have symptoms of inflammation, such as fever, pain, or swelling, or if you’re at higher risk for conditions like heart disease, autoimmune disorders, or certain infections. It can also be used to monitor treatment progress for chronic conditions.
How Is the Test Done?
A small blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure CRP levels. No special preparation is needed, but you may want to avoid strenuous activity or heavy meals before the test.
What Do Results Mean?
Results are reported in milligrams per liter (mg/L) or micrograms per milliliter (µg/mL). Higher than normal levels may indicate inflammation, infection, or other health concerns. Your doctor will interpret results in the context of your overall health and symptoms.
Reference range
Titer < 1:1 (Negative). A positive result is typically defined as a titer of ≥ 1:1 or greater, indicating intrathecal antibody synthesis. Reference ranges may vary by laboratory.N/A
No special patient preparation is required prior to lumbar puncture. Standard aseptic technique for CSF collection should be followed.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CRP
Frequently asked questions
What causes elevated CRP levels?
How often should CRP be checked?
Can CRP levels change with diet or exercise?
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