C-reactive protein (CRP) in plasma, measured by nephelometry
This test measures the level of C-reactive protein in your blood, a marker often checked for signs of inflammation or infection.
["CRP helps track inflammation, guiding decisions about treatment or further testing."]
Key facts at a glance
- LOINC
- 105642-3
- Short code
- CFREDNA
- Synonyms
- C. freundii compx DNA Spec Ql NAA+probe
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, leak-proof container appropriate for specimen type; serum separator tube (SST) for serum specimens; sterile transport tube or viral transport medium as required by testing laboratory protocol.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- probe-amp-tar
- CPT
- 87798 (infectious agent detection by nucleic acid, not otherwise specified)
- SNOMED
- 122455009 | Bacterial identification test (procedure)
- Specimen volume
- Minimum 1 mL serum; preferred 2-3 mL for adequate nucleic acid extraction. Volume requirements vary by specimen type and laboratory protocol.
- Stability
- Serum: stable for 24 hours at room temperature (20-25°C), 72 hours refrigerated (2-8°C), and up to 1 week at -70°C or below. Avoid repeated freeze-thaw cycles. Transport to laboratory on cold chain when delayed.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–72 hours
- Order
- routine
Why CRP is Tested
Doctors may order CRP testing to monitor conditions like infections, autoimmune diseases, or after surgery to check for inflammation. It can also help assess risk for heart disease or other chronic conditions.
What to Expect Before the Test
No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
Higher CRP levels often signal inflammation, but results alone don’t diagnose a specific condition. Your provider will interpret results in the context of your symptoms and medical history.
Common Conditions Monitored
CRP is used to monitor inflammation in conditions like rheumatoid arthritis, lupus, or after procedures like joint replacements. It may also be checked in people with suspected infections or heart disease.
Reference range
Negative (not detected). Reportable as Detected or Not Detected for Citrobacter freundii complex DNA.N/A
No special patient preparation required. Specimen should be collected prior to initiation of antimicrobial therapy whenever possible to maximize diagnostic yield.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: CRP is a nonspecific marker of inflammation. Elevated levels can indicate acute infections, chronic inflammatory diseases, or other systemic processes. It’s often used as a screening tool or to guide treatment adjustments, but it’s not definitive on its own.
Short name
CRP (Plasma) Nephelometry
Frequently asked questions
What causes CRP levels to rise?
How long does it take to get results?
Can diet or lifestyle affect CRP levels?
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