Laboratory Test Information Guide

Details for CSF Index

Test Name: CSF Index
Alternate Name(s): IgG/Alb CSF/Serum Ratio
Laboratory: Core
Specimen Type: Adult:
1.0 mL of CSF and a 5 mL Gold or 6 ml Red top Vacutainer

0-2 years: 0.5 mL Gold or Red Microtainer
2-10 years: 3 mL Gold or Red Vacutainer tube
Collection Information: Minimum CSF volume required is 700 l
Minimum serum volume required is 360 l

Collect blood aseptically in a Vacutainer tube.

Avoid hemolysis.

Serum from a 4.5 ml Green (Lithium Heparin) is also acceptable.
Test Schedule: Daily
Turnaround time from when specimen
is received in testing laboratory:
4 hours
Reference Range: 0.25 0.85
Effective Date:  
Revised Date: 2018-03-06
Critical Value:  
Interpretive Comments: In addition to oligoclonal banding, the CSF index is used in the diagnosis of multiple sclerosis.
The increase in the CSF immunoglobulin concentration in MS patients is due to increased intrathecal synthesis of IgG and not to an increase in the permeability of the blood-brain barrier.

The CSF index measures the CSF and serum concentrations of albumin and IgG. If the increase in CSF immunoglobulin concentration is due to increase permeability, the IgG/albumin ratio in the CSF compared with that in serum remains within expected values. If the increase is due to CSF-specific synthesis of IgG, the ratio is abnormally high.

The CSF index = (IgGCSF/Albumin CSF) / (IgGserum/Albuminserum)
Special Processing:  
Method of Analysis: Turbidimetry
Critical Information Required: Both CSF and serum are required to perform this test.
Storage & Shipment: CSF is refrigerated at 2 8oC for up to 3 days. Store at 20oC for longer storage.

Serum can be stored and/or shipped at room temperature for up to 8 hours or refrigerated at 2 8oC for up to 5 days. Store at 20oC for longer storage.
System Codes: 
Referred To:  

Questions? Comments? Contact Laura Gopaul