C-reactive protein (CRP) by nephelometry (serum/plasma)
This test measures the level of C-reactive protein in your blood, a marker often used to check for inflammation or infection.
["CRP helps track inflammation, which may signal infections, autoimmune conditions, or other health issues."]
Key facts at a glance
- LOINC
- 71884-1
- Short code
- COHgb MFr.DF BldV
- Synonyms
- COHgb MFr.DF BldV
- Category
- hematology
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 12
- Ref high
- 17.5
- Critical range
- 7 N/A – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85018
- SNOMED
- 900000000000003004
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order CRP testing to monitor conditions like arthritis, infections (e.g., pneumonia, urinary tract infections), or to evaluate how your body responds to treatments. It can also help assess risk for heart disease or other inflammatory disorders.
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 doctor know before the test.
What the Results Mean
Higher CRP levels often indicate inflammation, but results alone don’t diagnose a specific condition. Your doctor will compare your results to your symptoms and other tests for context.
Common Conditions Monitored
CRP is used to monitor chronic conditions like rheumatoid arthritis, lupus, or heart disease. It may also help guide treatment decisions for infections or post-surgery recovery.
Reference range
Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
CRP is a sensitive marker for inflammation but isn’t specific to any single disease. Elevated levels can appear with infections, autoimmune diseases, or trauma, while normal levels don’t rule out inflammation entirely. Your doctor will interpret results in relation to your overall health and medical history.
Short name
CRP
Frequently asked questions
What causes CRP levels to change?
How often should I get this test?
Can diet or exercise 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