Pathology Handbook

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Kappa Index

Alternative Names:

CSF Kappa FLC
CSF Kappa Free Light Chains

Laboratory:

Clinical Biochemistry

Test Code:

See Registration Instructions

Specimen Types:

Cerebrospinal Fluid
Blood

Container Types:

CSF Tube 2
SST

Adults Volume or Mass:

1 mL

Minimum/Paediatric Volume or Mass:

1 mL

Collection & Request Instructions:

Note that the test requires CSF and SERUM samples.

Serum must be collected +/- 24hrs of the CSF.

For electronic orders, use "CSF Kappa Index Careset".

For paper requests, please order "Kappa Index - CSF and serum"

Transport Instructions between Sites and/or Laboratories:

On Ice

Assay Frequency:

Weekly

Billing Information:

There is no MBS rebate for this test. The cost of the test is $60

Additional Notes:

Method: Immunonephelometry

CSF Kappa Index is an indicator of intrathecal immunoglobulin synthesis and can substitute for CSF "oligoclonal bands" in supporting the diagnosis of Multiple Sclerosis using the 2024 revised McDonald criteria.

A Kappa Index result >/= 6.1 is consistent with intrathecal immunoglobulin synthesis

Ref: X Montalban et al. Diagnosis of multiple sclerosis: 2024 revisions of the McDonald criteria. Lancet Neurol 2025; 24: 850–65

NOTE: In samples where a Kappa Index cannot be calculated, an "oligoclonal bands" test may be reflexed.