Nonspecific inflammatory marker (serum/plasma) measured by nephelometry
This test measures a protein in your blood that rises when your body is fighting inflammation, infection, or injury.
["CRP helps doctors track inflammation and guide treatment for conditions like infections, autoimmune diseases, or post-surgery recovery."]
Key facts at a glance
- LOINC
- 40740-3
- Short code
- OF Incubated NFr RBC
- Synonyms
- OF Incubated NFr RBC
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 4.2
- Ref high
- 5.9
- Critical range
- 2 N/A – 7 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85041
- SNOMED
- 900000000000003001
- 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 CRP testing to monitor symptoms of inflammation, check for infections (like pneumonia or appendicitis), or assess how well you’re responding to treatment for conditions like rheumatoid arthritis or heart disease. It can also help evaluate risks for heart disease or other chronic inflammatory conditions.
What to Expect Before the Test
No special preparation is needed. You may have blood drawn from a vein in your arm, similar to other blood tests. If you’re on blood thinners, let your doctor know before the test.
What the Results Mean
CRP levels vary depending on health status. Higher levels often indicate inflammation, but they can also be influenced by factors like recent illness, stress, or certain medications. Your doctor will interpret results in the context of your overall health and symptoms.
Common Conditions Monitored
CRP is commonly used to diagnose or monitor conditions such as infections (e.g., bacterial infections), autoimmune diseases (e.g., lupus, rheumatoid arthritis), heart disease, or post-surgical inflammation.
Reference range
Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated CRP levels are a general marker of inflammation and can signal underlying health issues. While it’s not specific to any single condition, it’s a useful tool for doctors to assess overall inflammatory activity and guide treatment decisions. CRP levels alone don’t diagnose a condition but often help guide further testing or treatment plans.
Short name
CRP (C-Reactive Protein)
Frequently asked questions
What causes CRP levels to change?
How soon will I get my results?
Can I lower my CRP levels naturally?
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 17, 2026. · Read our editorial policy