Felis ISSN 2398-2950

Cerebrospinal fluid: protein

Synonym(s): CSF

Contributor(s): Laurent Garosi


  • Total protein and protein fractions vary with type of central nervous sytem (CNS) pathology and etiology.
  • The concentration of protein in CSF is very low and is comprised almost entirely of albumin.
  • It is normally higher in the lumbar sample than the cerbellomedullary cistern one.
  • Increased protein in the cerebrospinal fluid (CSF) is a sensitive indicator of CNS disease, but it is the least specific change observed on CSF analysis.
  • It may be due to altered permeability of the blood-brain barrier (mainly albumin) and/or intrathecal immunoglobulin production.


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  • Because of its low concentration, specialized techniques and reagents are needed for quantitative analysis.
  • Precipitation and dye-binding methods.
  • Urinary protein reagent strips for detection of grossly elevated total protein.
  • Protein electrophoresis Serum protein electrophoresis  →   relative proportions, eg albumin versus globulin, helps identify source of protein: via increased permeability of blood-brain barrier or from local source (production by meninges).
  • The protein concentration in CSF is too low to be quatified using refractometry Refractometer.
  • In-house semi-quantitative approximation of the protein content can be performed using a standard urine dipstick bearing in mind that dipsticks are more efficient at detecting albumin and may give a false-negataive result in case of increased globulins. Protein can reliably be considered elevated based on a dipstick reading of 2+ or greater Urinalysis: protein.
  • Protein in CSF can be further analysed for the albumin quotient which detects disruptions in the blood-brain barrier, and for increased globulins, which indicates intrathecal production.


  • Widely available at commecial laboratories.
  • Urine dipstick semi-quantitative analysis can be done in practice.

Result Data

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Further Reading


Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Rand J S, Parent J, Percy D, Jacobs R (1994) Clinical, cerebrospinal fluid, and histological data from twenty-seven cats with primary inflammatory disease of the central nervous system. Can Vet J 35, 103-110 PubMed.
  • Jacobs R M, Cochrane S M, Lumsden J H, Norris A M (1990) Relationship of cerebrospinal fluid protein concentration determined by dye-binding and urinary dipstick methodologies. Can Vet J 31, 587-588.
  • Rand J S, Parent J, Jacobs R, Johnson R (1990) Reference intervals for feline cerebrospinal fluid: biochemical and serologic variables, IgG concentration, and electrophoretic fractionation. Am J Vet Res 51, 1049-1054.

Other sources of information

  • Wamsley H & Alleman A R (2004) Clinical pathology. In: BSAVA Manual of Canine and Feline Neurology. Platt S R & Olby N J (eds). British Small Animal Veterinary Association, Quedgely, Gloucester. pp 42-53.
  • Chrisman C L (1992) Cerebrospinal fluid analysis. Vet Clin North Am 22, 781-809.