C-reactive protein (CRP) 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 doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]
Key facts at a glance
- LOINC
- 9928-3
- Short code
- Q wave Dpth L-I
- Synonyms
- Q wave Dpth L-I
- Category
- coagulation
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ekg
- CPT
- 85610
- SNOMED
- 396252006
- 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 Is This Test Done?
Your doctor may order this test to check for signs of inflammation, monitor chronic conditions like arthritis or heart disease, or evaluate your response to treatment. It can also help detect infections or inflammation in other parts of your body, such as your joints or blood vessels.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it involves drawing blood from your vein. Avoid strenuous activity or taking anti-inflammatory medications for 24 hours before testing, as they can affect results.
What Happens During the Test?
A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a brief pinch, but the procedure is quick and usually painless. The blood is then sent to a lab for analysis.
What Are the Possible Results?
Results are reported in milligrams per deciliter (mg/dL) or micrograms per milliliter (µg/mL). Higher than normal levels may indicate inflammation, infection, or certain medical conditions. Your doctor will interpret the results in the context of your overall health and symptoms.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated CRP levels often signal inflammation, which can be caused by infections, autoimmune diseases (such as rheumatoid arthritis), heart disease, or other inflammatory conditions. It’s a useful marker for monitoring disease activity, guiding treatment decisions, and assessing recovery. Low or normal levels may suggest no active inflammation, but further evaluation is needed if symptoms persist.
Short name
CRP (Serum/Plasma)
Frequently asked questions
How long does it take to get my results?
Can lifestyle changes affect CRP levels?
Is CRP the same as a complete blood count (CBC)?
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