title: Assessment of the diagnostic performances of IgA heavy and light chain pairs in patients with IgA monoclonal gammopathy.
abstract: OBJECTIVE
  Preliminary results of the IgA Hevylite™ assay including the establishment of the 95% reference interval and assessment of the specificity and sensitivity in different populations are reported.
  
  
  METHODS
  The concentrations of IgA heavy and light chains (HLC) enabling to determine an IgAκ/IgAλ ratio were quantified in 119 apparently healthy individuals to generate 95% reference intervals. The specificity of this assay was assessed in 48 patients with an isolated polyclonal IgA increase. In a retrospective analysis of 68 patients with a monoclonal component type IgA (MC-IgA) identified by serum immunofixation (IFE), IgA HLC ratio values were compared with known results for serum protein electrophoresis (SPE) and free light chain (FLC) ratios.
  
  
  RESULTS
  The 95% reference range obtained in 119 controls (0.91-2.04) was close to that quoted by the manufacturer (0.80-2.04). Eight of the 48 patients (16.7%) with a polyclonal IgA increase had an IgA HLC ratio above the upper limit of the 95% reference interval. The IgA HLC ratio identified 65 (95.6%) among 68 patients with MC-IgA identified on the basis of IFE. For 34 of these patients (50%), MC-IgA was not detected by SPE due to its co-migration with alpha-2 or beta-globulins.
  
  
  CONCLUSIONS
  Compared with serum IFE, the IgA HLC ratio has a sensitivity of 95.6%. Further studies are needed to assess the specificity of the IgA HLC ratio in patients with an isolated polyclonal increase of serum IgA.
authors.affiliation: Laboratory of Clinical Chemistry, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium. fleur.wolff@erasme.ulb.ac.be
authors.forename: Fleur
authors.initials: F
authors.lastname: Wolff
authors.forename: France
authors.initials: F
authors.lastname: Debaugnies
authors.forename: Laurence
authors.initials: L
authors.lastname: Rozen
authors.forename: Dominique
authors.initials: D
authors.lastname: Willems
authors.forename: Fabian
authors.initials: F
authors.lastname: Brohet
authors.forename: Jonathan
authors.initials: J
authors.lastname: Brauner
authors.forename: Patrick
authors.initials: P
authors.lastname: Stordeur
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001797:Blood Protein Electrophoresis / Q000379:methods; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007143:Immunoglobulin Heavy Chains / Q000097:blood*; D007147:Immunoglobulin Light Chains / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010265:Paraproteinemias / Q000097:blood* / Q000175:diagnosis*; D011786:Quality Control; D012016:Reference Values; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D007070:Immunoglobulin A; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains