title: Combined use of Kappa Free Light Chain Index and Isoelectrofocusing of Cerebro-Spinal Fluid in Diagnosing Multiple Sclerosis: Performances and Costs.
abstract: BACKGROUND
  Isoelectrofocusing (IEF) to detect oligoclonal bands (OBCs) in cerebrospinal fluid (CSF) is the gold standard approach for evaluating intrathecal immunoglobulin synthesis in multiple sclerosis (MS) but the kappa free light chain index (KFLCi) is emerging as an alternative marker, and the combined/sequential uses of IEF and KFLCi have never been challenged.
  
  
  METHODS
  CSF and serum albumin, IgG, kFLC and lFLC were measured by nephelometry; albumin, IgG and kFLC quotients as well as Link and kFLC indexes were calculated; OCBs were evaluated by immunofixation. A total of 150 consecutive patients: 48 with MS, 32 with other neurological inflammatory diseases (NID), 62 with neurological non-inflammatory diseases (NNID), and 8 without any detectable neurological disease (NND) were investigated.
  
  
  RESULTS
  Both IEF and KFLCi showed a similar accuracy as diagnostic tests for multiple sclerosis. The high sensitivity and specificity associated with the lower cost of KFLCi suggested to use this test first, followed by IEF as a confirmative procedure. The sequential use of IEF and KFLCi showed high diagnostic efficiency with cost reduction of 43 and 21%, if compared to the contemporary use of both tests, or the unique use of IEF in all patients.
  
  
  CONCLUSIONS
  The "sequential testing" using KFLCi followed by IEF in MS represents an optimal procedure with accurate performance and lower costs.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Crespi
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Sulas
authors.forename: Riccardo
authors.initials: R
authors.lastname: Mora
authors.forename: Paola
authors.initials: P
authors.lastname: Naldi
authors.forename: Domizia
authors.initials: D
authors.lastname: Vecchio
authors.forename: Cristoforo
authors.initials: C
authors.lastname: Comi
authors.forename: Roberto
authors.initials: R
authors.lastname: Cantello
authors.forename: Giorgio
authors.initials: G
authors.lastname: Bellomo
mesh_terms: D015415:Biomarkers; D006801:Humans; D007074:Immunoglobulin G; D007145:Immunoglobulin kappa-Chains; D009103:Multiple Sclerosis; D009391:Nephelometry and Turbidimetry; D043025:Oligoclonal Bands
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G; D007145:Immunoglobulin kappa-Chains; D043025:Oligoclonal Bands