Basophilsnfrsnv
This test measures basophils and white blood cells in the fluid around your joints to help diagnose joint conditions.
{"A small sample of joint fluid is collected using a needle (arthrocentesis)","Elevated white blood cells often indicate inflammation, infection, or arthritis","Basophil count helps identify allergic or inflammatory joint conditions","Results guide treatment decisions for joint diseases","The procedure is generally safe but carries minor risks like infection or bleeding"}
Key facts at a glance
- LOINC
- 17833-5
- Short code
- SYNBASO
- Synonyms
- Basophils NFr Snv
- Category
- chemistry
- Sample
- fluid
- Container
- Sterile plain tube (red-top) or heparinized tube for synovial fluid collection; lavender-top (EDTA) tube acceptable for cell counts
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Manual microscopic differential cell count with Wright-Giemsa or May-Grünwald-Giemsa stained smear examined under light microscopy
- CPT
- 89051
- SNOMED
- 417270009
- Specimen volume
- 1-2 mL of synovial fluid minimum; 3-5 mL preferred for complete cell count and differential
- Stability
- Room temperature: 1 hour; Refrigerated (2-8°C): up to 24 hours; Cell morphology best preserved if analyzed within 1 hour of collection
- Hemolysis max
- 300
- TAT
- 1–4 hours
- Order
- routine
What is this test?
The Basophils/Leukocytes in Synovial Fluid test analyzes the fluid that lubricates your joints. Synovial fluid is a viscous liquid that helps joints move smoothly. This test counts two important components: leukocytes (white blood cells), which fight infection and inflammation, and basophils, a type of white blood cell involved in allergic reactions and inflammatory responses.
During the test, a doctor inserts a thin needle into your joint (usually the knee) to withdraw a small amount of synovial fluid. The fluid is then sent to a laboratory where specialists count the number of white blood cells and basophils under a microscope or using automated equipment.
Reference range
Normally absent or very rare (≤1% of leukocytes) in healthy synovial fluid. Basophils are typically not reported in routine synovial fluid analysis unless specifically identified.N/A
No special patient preparation required prior to arthrocentesis. Inform the ordering physician of any anticoagulant therapy as it may affect specimen collection.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings3
Frequently asked questions
Why do I need this test?
Is the joint fluid collection painful?
How should I prepare for the test?
When will I get my results?
Are there any risks from the joint fluid procedure?
Sources
- 1
- 2
- 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