C-reactive protein (serum/plasma) concentration
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
- 88455-1
- Short code
- CALEV
- Synonyms
- CEV Ab.IgG & IgM panel Ser IF
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top clot activator tube; aliquot into sterile transport vial
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Immunofluorescence Assay (IFA)
- CPT
- 86651
- SNOMED
- 395128001
- Specimen volume
- 1-2 mL serum (minimum 0.5 mL)
- Stability
- Serum stable for 7 days at 2-8°C; for extended storage, freeze at -20°C or below. Avoid repeated freeze-thaw cycles. Hemolyzed or lipemic specimens may yield unreliable results.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 48–168 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order a CRP test to check for signs of inflammation, monitor chronic conditions like rheumatoid arthritis or lupus, or evaluate your response to treatment. It can also help identify infections or determine if you’re healing properly after surgery or injury.
What to Expect Before the Test
No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw a blood sample. If you’re concerned about pain or discomfort, let your healthcare provider know.
What the Results Mean
Higher-than-normal CRP levels often indicate inflammation, but they can also be raised due to other factors like stress, certain medications, or obesity. Your doctor will interpret results in the context of your overall health and symptoms.
Common Conditions Monitored
CRP is commonly used to track conditions such as cardiovascular disease, infections (like pneumonia or sepsis), inflammatory bowel disease, and autoimmune disorders like lupus or rheumatoid arthritis.
Reference range
IgG: Negative (<1:16); IgM: Negative (<1:16). Titer ≥1:16 considered positive and suggestive of past (IgG) or recent/acute (IgM) infection.N/A
No special patient preparation is required. Fasting is not necessary. Specimen should be collected prior to administration of blood products or immunoglobulin therapy when possible, as these may interfere with serological results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
CRP is a sensitive marker of inflammation but isn’t specific to any single condition. Elevated levels may prompt further testing (like blood cultures or imaging) to identify the underlying cause. Low or normal levels don’t rule out inflammation entirely, especially in chronic conditions.
Short name
CRP
Frequently asked questions
What does a high CRP level mean?
Can diet or exercise affect CRP levels?
Is CRP tested only in blood, or can it be in other fluids?
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