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 or infection.
["CRP helps track inflammation in your body."]
Key facts at a glance
- LOINC
- 33614-9
- Short code
- CDT
- Synonyms
- CDT Other/Tf MFr SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube; plasma acceptable in lithium heparin or EDTA tubes
- Units
- N/A
- Ref low
- 0
- Ref high
- 1.7
- Critical range
- — – 2.5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–99 years
- Method
- Capillary electrophoresis or HPLC (High-Performance Liquid Chromatography)
- CPT
- 82373
- SNOMED
- 395143008
- Specimen volume
- 1-2 mL of serum or plasma
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 3 months; avoid repeated freeze-thaw cycles
- Hemolysis max
- 50
- Lipemia max
- 100
- Icterus max
- 25
- 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, monitor conditions like arthritis, infections, or heart disease, or evaluate responses to treatments. It can also help diagnose or monitor certain infections or autoimmune disorders.
What to Expect Before the Test
No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
Higher CRP levels often indicate inflammation, but they can also be influenced by factors like stress, recent illness, or certain medications. Your provider will interpret results in the context of your overall health and symptoms.
Common Conditions Monitored
CRP is commonly used to monitor conditions such as rheumatoid arthritis, infections (like pneumonia or sepsis), heart disease, and inflammatory bowel disease. It can also help assess how well you’re responding to treatments for these conditions.
Reference range
CDT (Carbohydrate-Deficient Transferrin) ratio: <1.7% (varies by laboratory and methodology); Asialo + Monosialo + Disialo transferrin fractions within established reference limitsN/A
No special preparation required. Patient should abstain from alcohol consumption for at least 2 weeks prior to testing for accurate baseline assessment, though acute alcohol intake does not significantly affect CDT levels in the short term.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: CRP as an Inflammation Marker
Short name
CRP (Nephelometry)
Frequently asked questions
What causes elevated CRP levels?
Can CRP levels be affected by diet or lifestyle?
How often should CRP levels be checked?
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 15, 2026. · Read our editorial policy