CSF analysis

Definition

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

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. 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.

Your doctor will ask you to lie flat for at least one hour after the lumbar puncture. You may develop a headache after the lumbar puncture. If it happens, drinking caffeinated beverages such as coffee, tea or soda may help.

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
• Bacteria (including that which causes syphilis, using a VDRL test)
• Cell count
• Chloride
• Cryptococcal antigen
• Glucose
• Glutamine
• Lactate dehydrogenase
• Oligoclonal banding to look for specific proteins
• Myelin basic protein 
  
• Total protein
• Whether there are cancerous cells present
• Opening pressure 
  

Normal Results

Normal results include:

• 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 (110 to 125 mmol/L)
• Fungus: None
• Glucose: 50 to 80 mg/dL or 2.77 to 4.44 mmol/L (or greater than two-thirds of blood sugar level)
• Glutamine: 6 to 15 mg/dL (410.5 to 1,026 micromol/L)
• Lactate dehydrogenase: less than 40 U/L
• Oligoclonal bands: 0 or 1 bands that are not present in a matched serum sample
• Protein: 15 to 60 mg/dL (0.15 to 0.6 g/L)
• Opening pressure: 90 to 180?mm of water
• Myelin basic protein: Less than 4ng/mL

Normal value ranges may vary slightly among different laboratories. Talk to your provider 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.

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
• Multiple sclerosis (MS)
• Alzheimer disease
• Amyotrophic lateral sclerosis (ALS)
• Pseudotumor Cerebrii
• Normal pressure hydrocephalus

References

Euerle BD. Spinal puncture and cerebrospinal fluid examination. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care. 7th ed. Philadelphia, PA: Elsevier; 2019:chap 60.

Griggs RC, Jozefowicz RF, Aminoff MJ. Approach to the patient with neurologic disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 396.

Karcher DS, McPherson RA. Cerebrospinal, synovial, serous body fluids, and alternative specimens. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 29.

Rosenberg GA. Brain edema and disorders of cerebrospinal fluid circulation. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 88.