Chemical tests
A few routine tests are usually performed on CSF samples.
  • CSF glucose - normal is about 2/3 the concentration of blood glucose. Glucose levels may decrease when cells that are not normally present use up (metabolise) the glucose. These may include bacteria or cells present due to inflammation (WBCs) or shed by tumours. Hence it is important to collect a blood specimen at the same time for comparison of glucose level.
  • CSF protein - only a small amount is normally present in CSF because proteins are large molecules and do not cross the blood/brain barrier easily. Decreases in CSF protein are not generally considered significant. Increases in protein are most commonly seen with:
If any of the initial tests are abnormal or if the doctor has reason to suspect a specific condition, then additional testing may be ordered. This may include one or more of the following:
  • CSF protein electrophoresis - separates different types of protein. Oligoclonal bands may be seen with multiple sclerosis and Lyme disease.
  • CSF IgG (Immunoglobulin G) - increased in some conditions, such as multiple sclerosis, herpes encephalitis, connective tissue diseases.
  • CSF amino acid analysis - may be requested in the investigation of several inherited metabolic diseases, particularly those presenting with unexplained seizures.

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