C-reactive protein, mass concentration in serum/plasma
This test measures the amount of C-reactive protein, a protein produced by the liver in response to inflammation in your body.
["CRP helps doctors assess inflammation and identify potential infections or other health issues."]
Key facts at a glance
- LOINC
- 12949-4
- Short code
- CDT
- Synonyms
- CDT SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube
- Units
- N/A
- Ref low
- 0
- Ref high
- 1.3
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–99 years
- Method
- Isoelectric focusing (IEF) or capillary electrophoresis
- CPT
- 82978
- SNOMED
- 395131000
- Specimen volume
- 1.0 mL serum
- Stability
- Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 50
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
What Is C-Reactive Protein Used For?
CRP is primarily used to monitor inflammation, track conditions like infections, autoimmune diseases, or post-surgery healing. It can also help evaluate risk for heart disease or other chronic conditions by indicating systemic inflammation.
How Is the Test Performed?
A blood sample is drawn from a vein, usually in your arm. The sample is then processed to separate serum or plasma, which is tested for CRP levels using an immunoassay method.
Why Might You Need This Test?
Your healthcare provider may order this test if you have symptoms of infection (like fever, pain), if you have an ongoing condition causing inflammation, or if you’re at higher risk for certain diseases (e.g., heart disease). It may also be used during follow-up for conditions like rheumatoid arthritis or after surgery.
What Do My Results Mean?
Results are interpreted based on clinical context rather than absolute values alone. Elevated CRP levels may signal inflammation, while lower levels suggest reduced inflammation. Your doctor will discuss findings in relation to your symptoms and medical history.
Reference range
Normal CDT (carbohydrate-deficient transferrin) values are typically <1.3% or <2.5% depending on assay methodology. Reference ranges should be established by the performing laboratory based on their specific method.N/A
No fasting required. Patient should abstain from alcohol for at least 2 weeks prior to testing for accurate assessment of chronic alcohol abuse. Recent heavy alcohol consumption within 24-48 hours may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CRP (Serum/Plasma)
Frequently asked questions
What causes CRP levels to change?
How soon will I get my results?
Can I eat or drink before this test?
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 11, 2026. · Read our editorial policy