Basophilsnfrdfsnvmanual
This test measures the percentage of basophils (a type of white blood cell) in synovial fluid from a joint using manual microscopic examination.
{"Measures basophil percentage in joint fluid","Helps diagnose joint inflammation, infection, or arthritis","Performed by manually counting cells under a microscope","Part of a complete joint fluid analysis (cell count with differential)","Results help doctors determine the cause of joint swelling"}
Key facts at a glance
- LOINC
- 71621-7
- Short code
- SYNBASO
- Synonyms
- Basophils NFr.DF Snv Manual
- Category
- chemistry
- Sample
- fluid
- Container
- Sterile plain tube (red-top or screw-cap plastic tube) without anticoagulant for clot formation, or lavender-top (EDTA) tube for cell count preservation; sterile container for joint aspirate collection
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- manual-count
- CPT
- 89051
- SNOMED
- 46328008
- Specimen volume
- 1-5 mL of synovial fluid is recommended for complete fluid analysis including manual differential count
- Stability
- Room temperature: 1-2 hours for optimal cell preservation; Refrigerated (2-8°C): up to 24 hours in EDTA tube. Cell morphology degrades rapidly; immediate processing preferred.
- Hemolysis max
- 300
- TAT
- 1–4 hours
- Order
- routine
What is this test?
The Synovial Fluid Basophil Count is a laboratory test that determines the percentage of basophils (a type of white blood cell) in the total number of white blood cells (leukocytes) found in synovial fluid. Synovial fluid is a viscous liquid that lubricates joints and reduces friction between bones. This test is performed manually by a laboratory technician who examines the fluid under a microscope after staining a sample.
Reference range
Normally absent or rare (<1% of total leukocytes). Basophils are not typically present in healthy synovial fluid.N/A
Arthrocentesis should be performed under sterile conditions by a qualified healthcare professional. No specific patient fasting required. Discontinue non-essential anticoagulants if clinically feasible prior to aspiration, per physician direction.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Basophils are white blood cells that play a role in allergic reactions and inflammation. An elevated basophil count in synovial fluid may indicate inflammatory conditions such as rheumatoid arthritis, gout, or psoriatic arthritis. It may also suggest an allergic or hypersensitivity reaction within the joint. This test is typically performed as part of a complete synovial fluid analysis, which includes total white blood cell count, differential count (neutrophils, lymphocytes, monocytes, eosinophils, basophils), and examination for crystals or bacteria.
Frequently asked questions
Why do I need this test?
How is the sample collected?
Does the test have any risks?
What do abnormal results mean?
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