Basophilsfld
A basophil count measures the number of basophils, a type of white blood cell, in your blood or body fluid.
{"Basophils are white blood cells that play a key role in allergic reactions and inflammation","This test helps doctors diagnose conditions affecting your immune system","Normal basophil counts are relatively low; significant changes may indicate underlying health issues"}
Key facts at a glance
- LOINC
- 35071-0
- Short code
- BASO-BF
- Synonyms
- Basophils # Fld
- Category
- chemistry
- Sample
- serum
- Container
- Sterile body fluid collection container; EDTA (lavender-top) tube preferred for cell count and differential analysis; heparinized tubes acceptable for some body fluids
- Units
- N/A
- Ref low
- 0
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Automated cell counting with flow cytometry and microscopic differential; body fluid analysis performed on automated hematology analyzers with manual microscopic confirmation when indicated
- CPT
- 89051
- SNOMED
- 442940003
- Specimen volume
- Minimum 1 mL for cell count; 3-5 mL preferred for complete analysis including differential
- Stability
- Refrigerated (2-8°C): 24 hours for accurate cell count and differential. Specimens should be analyzed as soon as possible, preferably within 2 hours of collection, to prevent cell degradation.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 1–4 hours
- Order
- routine
What is this test?
The basophil count test measures the number of basophils in your blood. Basophils are the least common type of white blood cell, making up less than 1% of all white blood cells. Despite their small numbers, they play an important role in your immune system by releasing histamine during allergic reactions and fighting parasitic infections.
This test is typically performed as part of a complete blood count (CBC) with differential, which measures the different types of white blood cells in your blood. The test uses a blood sample, usually drawn from a vein in your arm.
Reference range
Reference ranges for basophils in body fluid vary by fluid type. Pleural fluid: typically <100 cells/μL; Peritoneal fluid: typically <100 cells/μL; Synovial fluid: typically absent or rare; CSF: typically 0 cells/μL. Clinical interpretation should be performed in conjunction with total nucleated cell count and clinical context.N/A
No fasting required. Patient preparation depends on the specific body fluid being collected. For paracentesis, thoracentesis, or lumbar puncture, follow standard sterile collection protocols.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings2
Frequently asked questions
Do I need to fast before this test?
Is the test painful?
What do abnormal results mean?
Can medications affect my basophil count?
Sources
- 1
- 2
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