C-reactive protein (CRP) – Serum/Plasma Concentration
This test measures the level of C-reactive protein, a protein produced by your liver in response to inflammation or infection in your body.
["CRP helps track inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]
Key facts at a glance
- LOINC
- 42374-9
- Short code
- N men sg Y Ag Islt Ql Aggl
- Synonyms
- N men sg Y Ag Islt Ql Aggl
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- aggl
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why CRP Matters in Your Health
CRP is a marker that signals your body’s immune response. It rises when tissues are damaged, infections occur, or inflammatory conditions (like arthritis) are present. Your doctor may order this test to check for hidden inflammation or to guide treatment for conditions like heart disease or autoimmune disorders.
When This Test Is Done
CRP tests are commonly performed to evaluate general inflammation, monitor chronic conditions (e.g., rheumatoid arthritis), or assess risk for conditions like heart disease. They may also be used before or after surgeries to monitor healing or detect complications.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a metabolic panel. Avoid strenuous activity or taking anti-inflammatory medications (like ibuprofen) for 48 hours before testing, as they can affect results.
What the Results Mean
Results are interpreted based on your overall health and medical history. Higher-than-normal levels may indicate inflammation, infection, or other health issues. Your doctor will discuss findings in the context of your symptoms and other tests.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
CRP is a key marker for diagnosing and managing inflammatory diseases. Low levels may suggest no active inflammation, while elevated levels can prompt further investigation into infections, autoimmune conditions, or other systemic issues. It’s also used to monitor treatment effectiveness in chronic inflammatory disorders.
Short name
CRP
Frequently asked questions
What causes CRP levels to change?
How long does it take to get results?
Can I take anything to lower my 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