Cerebrospinal fluid (CSF) analysis is a group of laboratory tests that measure chemicals in the fluid that surrounds and protects the brain and spinal cord. The tests may look for proteins, sugar (glucose), and other substances.
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. Less common ways to take a fluid sample include:
- Cisternal puncture
- Removal of CSF from a tube that is already in the CSF, such as a shunt, ventricular drain, or pain pump
- Ventricular puncture
After the sample is taken, it is sent to the laboratory for evaluation.
How to prepare for the test
Your health care provider will tell you how to prepare for 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: 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/dL(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/dL
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
Note: mg/dL = milligrams per deciliter
What abnormal results mean
Griggs RC, Jozefowicz RF, Aminoff MJ. Approach to the patient with neurologic disease. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 403.
Rosenberg GA. Brain edema and disorders of cerebrospinal fluid circulation. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC, eds. Bradley’s Neurology in Clinical Practice. 6th ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap 59.
Martorana A, Sancesario GM, Esposito Z, et al. Plasmin system of Alzheimer’s disease: CSF Analysis. J Neural Transm. 2012:119:763-769.