Protein, CSF

Diagnostic Use

CSF protein is largely an ultrafiltrate of plasma, and is predominantly made up of low molecular weight and medium molecular weight proteins. In normal health, the protein concentration of CSF is approximately 100-fold less than that of plasma.

There are many causes of an elevated CSF protein. Therefore this test is a non-specific biomarker of CNS pathology that may be of some diagnostic use when applied to the relevant clinical context.

Department

Core Biochemistry

Delphic Registration Code

CSFB

Turnaround Time

2 hours

Test Code

3761

Specimen Type

• CSF

Specimen Requirements

Tube/Container Type:

Preferred

• Pottle

Preferred Sample Volume (ml)

0.2

Additional Specimen Information

Heavily blood stained specimens and specimens containing clots are unsuitable for analysis

Aliquot Instructions

Minimum Volume (ml)

0.2

Interpretation

Elevations of CSF protein may occur for a number of reasons.  The table below is adapted from Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 6th Edition (Rifai, Horvath & Wittwer) and is a non-exhaustive list of some of the more common causes of a high CSF protein.  The result should be interpreted in the clinical context which will allow for a narrowing of the differential diagnosis.

 

Increase in permeability of blood-brain barrier	Meningitis (bacterial, viral, fungal), encephalitis, CNS neoplasms
Intrathecal production of protein (usually immunoglobulin)	Multiple sclerosis and other demyelinating conditions (e.g. Guillain-Barre syndrome).
Cerebral haemorrhage	Sub-arachnoid haemorrhage, subdural haematoma, intracerebral haemorrhage
Mechanical obstruction of CNS flow	Spinal cord tumour or abscess
Specimen contamination	Traumatic tap

 

A common cause of a high CSF protein is contamination with venous blood due to a traumatic collection (bloody tap).  CSF protein can be markedly elevated depending upon the degree of contamination.  CSF protein results usually should not be interpreted in blood-stained specimens.

Reference Intervals

0.15 – 0.40 g/L

This reference interval applies to adult patients where the CSF is collected from a lumbar puncture.  The CSF protein concentration tends to be higher in neonates, and is lower in CSF specimens collected from the ventricular system.

Test Method

Spectrophotometry (pyrogallol red) on a Beckman Coulter AU5822 analyser.

Non-Funded Test Cost

$11.11 (Exclusive of GST)

Billing Code

3761

Contact Information

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