C-reactive protein (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 doctors assess inflammation, often used to monitor conditions like infections, autoimmune diseases, or after surgery."]
Key facts at a glance
- LOINC
- 34544-7
- Short code
- Comp C3 + C4 Pnl SerPl-mCnc
- Synonyms
- Comp C3 + C4 Pnl SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 of inflammation, meaning it rises when your body fights off infections, heals injuries, or responds to conditions like arthritis or heart disease. High levels may signal an active inflammatory process, while low levels suggest reduced inflammation.
When This Test Is Ordered
Your healthcare provider may order CRP testing to check for infections, monitor chronic conditions like rheumatoid arthritis, evaluate heart health, or assess response to treatment for conditions causing inflammation.
What to Expect Before the Test
No special preparation is needed. You may have a blood draw at a clinic or lab, where a small needle is used to collect serum or plasma. If you’re on blood thinners, inform your provider beforehand.
What the Results Mean
Results are typically reported in milligrams per liter (mg/L). While reference ranges vary by lab, very high levels may indicate severe inflammation or infection, while very low levels could suggest no active inflammation. Your provider will interpret results in the context of your overall health.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated CRP levels often correlate with conditions like infections (e.g., pneumonia, urinary tract infections), autoimmune diseases (e.g., lupus, rheumatoid arthritis), or acute events like heart attacks or strokes. It’s also used to monitor treatment effectiveness, such as for rheumatoid arthritis or inflammatory bowel disease. However, CRP alone isn’t diagnostic—it’s one piece of the puzzle, often combined with other tests.
Short name
CRP (Serum/Plasma)
Frequently asked questions
How often will I need this test?
Can lifestyle changes affect CRP levels?
What if my CRP is persistently high?
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