title: A multicentre study comparing two methods for serum free light chain analysis.
abstract: BACKGROUND
  Serum free light chain analysis is now well established in the investigation of monoclonal gammopathies. In the UK there has, until recently, been a single supplier of kits for such analysis. Recently, a second method using monoclonal antisera was introduced. We have compared the performance of these two kits in four routine laboratories.
  
  
  METHODS
  Samples submitted for routine analysis (327 samples, 258 [79%] from patients with B-cell lymphoproliferative disease) for serum free light chains were tested by both technologies (Freelite, Binding Site and N Latex FLC, Siemens), according to the manufacturers' instructions.
  
  
  RESULTS
  Qualitative data were available by both methods on 313 samples for serum free kappa chains and 324 samples for lambda free light chains. We found poor correspondence of 81% for kappa and 74% for lambda. Five percent of samples were significantly discordant in these assays.
  
  
  CONCLUSIONS
  These assays perform very differently in clinical practice. They cannot be used interchangeably, especially if monitoring patient responses to therapy.
authors.affiliation: Immunology and Immunogenetics, Pathology Sciences, North Bristol NHS Trust, Southmead Hospital, Westbury-on-Trym, Bristol BS10 5NB, UK. Robert.lock@nbt.nhs.uk
authors.forename: R J
authors.initials: RJ
authors.lastname: Lock
authors.forename: R
authors.initials: R
authors.lastname: Saleem
authors.forename: E G
authors.initials: EG
authors.lastname: Roberts
authors.forename: M J
authors.initials: MJ
authors.lastname: Wallage
authors.forename: T J
authors.initials: TJ
authors.lastname: Pesce
authors.forename: A
authors.initials: A
authors.lastname: Rowbottom
authors.forename: S J
authors.initials: SJ
authors.lastname: Cooper
authors.forename: E D
authors.initials: ED
authors.lastname: McEvoy
authors.forename: J L
authors.initials: JL
authors.lastname: Taylor
authors.forename: S
authors.initials: S
authors.lastname: Basu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000276:immunology; D005260:Female; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D007145:Immunoglobulin kappa-Chains / Q000097:blood*; D007146:Immunoglobulin lambda-Chains / Q000097:blood*; D008232:Lymphoproliferative Disorders / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D010265:Paraproteinemias / Q000097:blood / Q000175:diagnosis; D011933:Reagent Kits, Diagnostic / Q000592:standards
chemical_list: D000911:Antibodies, Monoclonal; D007147:Immunoglobulin Light Chains; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D011933:Reagent Kits, Diagnostic