Determination of κFLC and κ Index in cerebrospinal fluid: a valid alternative to assess intrathecal immunoglobulin synthesis.

Intrathecal immunoglobulin synthesis is observed in several disorders of the central nervous system, but its detection by current laboratory tests is relatively insensitive and operator depending. We assessed the diagnostic accuracy of a nephelometric assay for k free light chain determination in cerebrospinal fluid and serum. The patients were grouped according to clinical and laboratory criteria.