C-reactive protein (high-sensitivity) concentration, mass concentration in serum/plasma
This test measures a protein produced by your liver in response to inflammation, helping detect low-level inflammation in your body.
["hs-CRP helps track subtle inflammation that may not show up in other tests."]
Key facts at a glance
- LOINC
- 93353-1
- Short code
- CD64N
- Synonyms
- CD64 Ag EntNum Neut FC
- Category
- chemistry
- Sample
- serum
- Container
- EDTA (lavender-top) blood collection tube; heparinized tubes may be acceptable per laboratory protocol
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Critical range
- — – 2 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- flow-cytometry
- CPT
- 86356
- SNOMED
- 313069005
- Specimen volume
- 3–5 mL whole blood in EDTA tube; minimum 1 mL for pediatric samples
- Stability
- Specimen should be processed within 4–6 hours of collection when stored at room temperature (18–25°C). If delayed, refrigerate at 2–8°C and analyze within 24 hours. Do not freeze whole blood specimens.
- 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 monitor chronic conditions like heart disease, arthritis, or other inflammatory disorders. It can also be used to assess risk for future health issues, such as heart attacks or strokes, especially in people with no obvious symptoms of inflammation.
What Does a High or Low Result Mean?
Elevated levels may indicate ongoing inflammation, which can be linked to conditions like infections, autoimmune diseases, or metabolic issues. Lower-than-normal levels might suggest reduced inflammation, but they don’t always mean you’re healthy.
How Is This Test Performed?
A small blood sample is taken from a vein in your arm. The blood is sent to a lab where it’s analyzed to measure the protein concentration using a sensitive detection method.
What Should You Expect Before or After the Test?
No special preparation is needed, but inform your doctor about any medications you’re taking, as some may affect results. After the test, you may experience mild bruising or soreness at the injection site, which usually goes away quickly.
Reference range
CD64 expression on neutrophils is typically expressed as antibodies per cell (Ab/cell) or mean fluorescence intensity (MFI). Reference values vary by laboratory; generally, a CD64 index or absolute CD64 molecules per neutrophil <1.0 Ab/cell is considered normal. Values between 1.0–2.0 may be borderline, and values >2.0 are suggestive of infection or sepsis.N/A
No special patient preparation required. Fasting is not necessary. Recent administration of immunomodulatory therapies (e.g., corticosteroids, IVIG, G-CSF) may affect CD64 expression and should be noted on the requisition.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
hs-CRP
Frequently asked questions
What does a high hs-CRP level mean?
Can lifestyle changes lower my hs-CRP level?
Is hs-CRP the same as a regular C-reactive protein test?
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