Cerebrospinal Fluid (CSF) Testing
- Also Known As:
- CSF Analysis
- Spinal Fluid Analysis
- Formal Name:
- Cerebrospinal Fluid Analysis

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At a Glance
Why Get Tested?
To diagnose a disease or condition affecting the central nervous system such as meningitis, encephalitis, bleeding around the brain, cancer, or autoimmune disorder
When To Get Tested?
When your health care provider suspects that your symptoms are due to a condition or disease involving your central nervous system
Sample Required?
A sample of cerebrospinal fluid (CSF) collected by a health care practitioner from the lower back using a procedure called a lumbar puncture or spinal tap
Test Preparation Needed?
You will be instructed to empty your bladder and bowels prior to sample collection. It will be necessary to lie still in a curled-up fetal position during the collection and to lie flat and still for a time period after the collection.
What is being tested?
Cerebrospinal fluid (CSF) is a clear, watery liquid that flows around the brain and spinal cord, surrounding and protecting them. CSF testing is performed to evaluate the level or concentration of different substances and cells in CSF in order to diagnose conditions affecting the brain and spinal cord (central nervous system).
CSF is produced and secreted by the choroid plexus, a special tissue that has many blood vessels and that lines the small cavities or chambers (ventricles) in the brain. The total CSF volume is 3-5 ounces (90-150 mL) in adults and 0.3-2 ounces (10-60 mL) in newborns. CSF is continually produced, circulated, and then absorbed into the blood. About 17 ounces (500 mL) of CSF are produced each day. This rate of production means that all the CSF is replaced every few hours.
A protective, semi-permeable barrier separates the brain from the bloodstream. This blood-brain barrier allows some substances to cross and prevents other substances from crossing. Importantly, it helps keep large molecules, toxins, and most blood cells away from the central nervous system. Any condition that disrupts this protective barrier may result in a change in the normal level or makeup of CSF. Because CSF surrounds the brain and spinal cord, testing a sample of CSF can be very valuable in diagnosing a variety of conditions affecting the central nervous system.
Although a sample of CSF may be more difficult to obtain than, for example, urine or blood, the results of CSF testing may reveal more directly the cause of central nervous system conditions. The following are some examples:
- Meningitis, an infection of the layers that cover the brain and spinal cord (meninges), and encephalitis, an infection in the brain
- Autoimmune diseases that affect the central nervous system, such as multiple sclerosis
- Cancers of the central nervous system or cancers that have spread to the central nervous system, such as leukemia
- Alzheimer disease, an irreversible form of dementia
Common Questions
Details on CSF Tests
View Sources
Sources Used in Current Review
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Sources Used in Previous Reviews
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