Test Entry - Detail

CSF - IgG Index

General

Clinical Use:

An increased ratio generally indicates increased permeability of the blood-brain barrier. Often performed on patients suspected of having multiple sclerosis. Increased levels of CSF IgG can be due to excess production of IgG within the central nervous system (multiple sclerosis and several other diseases) or it can be due to leakage (ie. increased barrier permeability) of plasma proteins into the CSF (due to inflammation eg idiopathic polyneuropathy, neurosyphilis, or trauma). To discriminate between these two possibilities, the IgG index is calculated from IgG and albumin measurements performed in CSF and serum. The calculation usually takes the following form: An elevated IgG index, which indicates increased production of IgG within the central nervous system, is found in about 90% of MS cases. An increased ratio (CSF/serum) generally indicates increased permeability of the blood brain barrier. It should be noted that increased permeability could mask moderate increases in CNS IgG synthesis.

Availability:

Samples are batched and tested 3 times a week.

Aliases/Synonyms:

CSF - IgG:Albumin Ratio, IgG Index (CSF), IgG:Albumin Ratio (CSF),

Code:

CIGG

Handling Instructions (to laboratory):

Send samples chilled.

Hyperlink:

Reference Interval:

<=0.034 g/L

Collection Requirements

Container:

CSF Tube 1 (CSF1), and, Serum Sep. Tube-SST (GOLD),

Sample Type:

See container

Minimum Collection Volume:

500uL

Collection Instructions:

Processing Requirements

Alternate Containers:

Processing Instructions:

Centrifuge, separate and freeze plasma. Freeze CSF sample.

Minimum Assay Volume:

500uL

Stability:

Transport Instructions (to testing laboratory):

Requests should be reviewed by Duty Biochemist prior to transport.
Send samples frozen on dry ice.

Testing Locations

Performed at:

Section	Department	Site	Contact Phone
-	Laboratory	Hunter Area Pathology Service	(02) 4921 4000

Last Updated : 08-10-2025 15:29