Understanding Your Laboratory Test: What It Is, How It Is Done, and Why It Is Ordered
A test that measures the percentage of basophils (a type of white blood cell) in the fluid surrounding the brain and spinal cord.
{"The test uses a lumbar puncture (spinal tap) to collect cerebrospinal fluid (CSF)","It counts the percentage of basophils among all white blood cells in the fluid","Normal CSF has very few or no basophils","Elevated levels may indicate infection, inflammation, or other conditions","Results help doctors diagnose and monitor diseases affecting the central nervous system"}
Key facts at a glance
- LOINC
- 71662-1
- Short code
- CSF BASO
- Synonyms
- Basophils NFr.DF CSF Manual
- Category
- chemistry
- Sample
- csf
- Container
- Sterile CSF collection tube (tube #3 or #4 recommended for cell counts to minimize blood contamination from traumatic tap); polypropylene cryotube acceptable
- Units
- N/A
- Ref low
- 0
- Ref high
- 5
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- manual-count
- CPT
- 89051
- SNOMED
- 395007009
- Specimen volume
- 0.5-1.0 mL of cerebrospinal fluid
- Stability
- Cell counts should be performed within 1-2 hours of collection for optimal accuracy. If delayed, specimen may be refrigerated at 2-8°C for up to 4 hours; however, cell viability decreases over time.
- Hemolysis max
- 200
- TAT
- 1–4 hours
- Order
- routine
This test is a laboratory evaluation that provides your healthcare team with important information about your health. It can help detect a medical condition, monitor an existing problem, or check how well a treatment is working for you.
The CSF Basophil Count test measures the percentage of basophils (a type of white blood cell) in the cerebrospinal fluid (CSF). CSF is the clear, protective fluid that surrounds the brain and spinal cord. Basophils are a component of the immune system and are normally found in very low numbers in healthy CSF.
The test is usually performed by a trained healthcare professional, such as a nurse or phlebotomist, in a clinic, hospital, or laboratory. Depending on the type of test, a small sample of blood, urine, or other body material may be collected, and the procedure is typically quick, allowing you to return to your normal activities soon afterward.
A healthcare provider collects a sample of cerebrospinal fluid through a procedure called a lumbar puncture (spinal tap). During this procedure, a needle is inserted into the lower back to draw out fluid from the space around the spinal cord. The sample is then examined under a microscope in a laboratory, where a technician manually counts and calculates the percentage of basophils relative to other white blood cells present.
Your doctor may order this test to help determine the cause of symptoms you are experiencing, screen for certain diseases before they cause noticeable problems, or monitor a condition you already have. The results help guide decisions about your diagnosis, treatment plan, and overall care.
This test is typically ordered when a doctor suspects an infection, inflammation, or other abnormality in the brain or spinal cord. It helps distinguish between different types of conditions affecting the central nervous system and can provide important diagnostic information when patients have symptoms such as severe headache, fever, neck stiffness, or neurological changes.
Reference range
Basophils: 0%; Leukocytes (total WBC): 0-5 cells/μL in adults. Basophils are rarely present in normal CSF.N/A
No fasting required. Lumbar puncture should be performed under sterile conditions. Patient should remain still during the procedure. Local anesthesia may be administered at the discretion of the performing physician.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
In healthy individuals, cerebrospinal fluid typically contains very few or no basophils. Elevated basophil levels in CSF (basophilia) may indicate conditions such as bacterial or viral meningitis, fungal infections, parasitic infections, inflammatory conditions like multiple sclerosis, certain leukemias, or other diseases affecting the central nervous system. The interpretation of results requires consideration of other CSF findings (such as total white blood cell count, protein, and glucose levels) and the patient's clinical symptoms. Your healthcare provider will explain what your specific results mean in the context of your overall health condition.
Frequently asked questions
Does the test require fasting?
How long does it take to get results?
Is the lumbar puncture procedure painful?
What are the risks of a lumbar puncture?
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