CSF analysis

Definition

Cerebrospinal fluid (CSF) analysis is a group of laboratory tests that measure proteins, sugar (glucose), and other chemicals in the fluid that surrounds and protects the brain and spinal cord.

Alternative Names

Cerebrospinal fluid analysis

How the test is performed

A sample of CSF is needed. A lumbar puncture, also called a spinal tap, is the most common way to collect this sample. For information on this procedure, see lumbar puncture. Other methods for collecting CSF are rarely used, but may be recommended in some cases. See also:

• Cisternal puncture
• Removal of CSF from a tube that is already in the CSF, such as a shunt or ventricular drain
• Ventricular puncture

After the sample is taken, it is sent to the laboratory for evaluation.

How to prepare for the test

See: Lumbar puncture

How the test will feel

See: Lumbar puncture

Why the test is performed

Analysis of CSF can help detect certain conditions and diseases. All of the following can be, but are not always, measured in a sample of CSF:

• Antibodies and DNA of common viruses
• Bacteria (including that which causes syphilis; see:VDRL test)
• Cell count
• Chloride
• Cryptococcal antigen
• Glucose
• Glutamine
• Lactate dehydrogenase
• Oligoclonal banding to look for specific proteins
• Total protein
• Whether there are cancerous cells present

Normal Values

• Antibodies and DNA of common viruses: None
• Bacteria: No bacteria grows in a lab culture
• Cancerous cells: No cancerous cells present
• Cell count: less than 5 white blood cells (all mononuclear) and 0 red blood cells
• Chloride: 110 to 125 mEq/L
• Fungus: None
• Glucose: 50 to 80 mg/100 mL (or greater than two-thirds of blood sugar level)
• Glutamine: 6 to 15 mg/dL
• Lactate dehydrogenase: less than 2.0 to 7.2 U/mL
• Oligoclonal bands: 0 or 1 bands that are not present in a matched serum sample
• Protein: 15 to 60 mg/100 dL

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

An abnormal CSF analysis result may be due to many different causes, including:

• Cancer
• Encephalitis (such as West Nile and Eastern Equine)
• Hepatic encephalopathy
• Infection
• Inflammation
• Reye syndrome
• Meningitis due to bacteria, fungus, tuberculosis, or a virus

What the risks are

For information regarding risks of a spinal tap, see: Lumbar puncture

References

Griggs RC, Józefowicz RF, Aminoff MJ. Approach to the patient with neurologic disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 418.