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 identify inflammation, often used to monitor conditions like infections or autoimmune diseases."]
Key facts at a glance
- LOINC
- 77344-0
- Short code
- DEVCLT
- Synonyms
- CC # Implnt dev Cult
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, leak-proof, wide-mouth container without preservatives (e.g., sterile screw-cap urine cup or sterile wide-mouth jar). For catheters, a sterile specimen cup is appropriate. For orthopedic hardware and large devices, a sterile 50 mL conical tube or sterile specimen jar is recommended.
- Units
- N/A
- Ref low
- 15
- Ref high
- 20
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- culture
- CPT
- 87077
- SNOMED
- 441510005
- Specimen volume
- Entire implanted device (catheter segment, prosthesis, hardware) submitted when possible. If device is large, submit representative segments. Sonicate with 50-400 mL of sterile saline or Ringer's lactate depending on device size; minimum 1-5 mL of sonicate fluid plated. Catheter tips: submit 3-5 cm distal segment.
- Stability
- Submit to laboratory as soon as possible. Room temperature: ≤2 hours. Refrigerated (4°C): ≤24 hours. Do not freeze. Sonicate fluid should be processed within 2 hours of device sonication. Delayed processing may result in overgrowth of contaminating organisms or death of fastidious pathogens, leading to false-negative or false-positive results.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 48–120 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order this test to check for signs of inflammation, monitor chronic conditions like arthritis or heart disease, or evaluate responses to treatments. It can also help diagnose infections or assess risks for certain health issues.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast before the test if it’s part of a broader blood panel, but CRP alone typically doesn’t require fasting. Bring any medications you’re taking to your appointment.
What Happens During the Test?
A healthcare provider will draw blood from a vein, usually in your arm. The blood sample is sent to a lab for analysis using nephelometry, a method that measures how much light is scattered by the protein in your blood.
What Are Possible Results?
Results are reported in milligrams per liter (mg/L). Higher levels may indicate inflammation, infections, or other health concerns. Your doctor will interpret the results in the context of your overall health and symptoms.
Reference range
Negative: No growth or <15 CFU/device (sonication method); Interpretation depends on clinical context, device type, and presence of symptoms. Generally, ≥15-20 CFU per device from sonicate fluid or ≥1 CFU from direct catheter culture is suggestive of true infection.N/A
No special patient preparation is required prior to device removal. The implanted device should be removed aseptically and submitted to the microbiology laboratory promptly in a sterile container without fixatives or preservatives. If the device cannot be transported immediately, it may be stored at room temperature for up to 2 hours or refrigerated at 4°C for up to 24 hours. Avoid contamination of the device with skin or environmental flora during removal.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CRP (Serum/Plasma)
Frequently asked questions
How long does it take to get my CRP test results?
Can I eat or drink before my CRP test?
What if my CRP level is high?
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