C-reactive protein (CRP) mass concentration in 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, autoimmune diseases, or after surgery."]
Key facts at a glance
- LOINC
- 13085-6
- Short code
- C4NEPH
- Synonyms
- C4 NeF SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or serum separator tube (SST)
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Enzyme-linked immunosorbent assay (ELISA) or Hemolytic assay
- CPT
- 86161
- SNOMED
- 395128002
- Specimen volume
- 1-2 mL of serum
- Stability
- Stable for 24 hours at 2-8°C; for longer storage, freeze at -70°C or below. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 72–168 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order CRP testing to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or assess risk for heart disease. It can also help evaluate infections, injuries, or responses to treatments.
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 Happens During the Test?
Blood is collected in a tube and sent to a lab for analysis. The test typically takes a few minutes, and results are usually available within 24–48 hours.
What the Results Mean
Higher-than-normal 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.
Reference range
Negative: <1:5 titer or <20% of reference standard; Positive results reported as detected or quantified titerN/A
No fasting required. Patient should be well-hydrated. Avoid hemolyzed specimens.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CRP
Frequently asked questions
What causes elevated CRP levels?
Can CRP levels be affected by diet or lifestyle?
How often should CRP 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