title: Diagnostic reference range of κ/λ free light chain ratio to screen for Bence Jones proteinuria is not significantly influenced by GFR.
abstract: OBJECTIVE
  The aim of our study was to analyse whether the κ/λ free light chain ratio reference range for screening for Bence Jones proteinuria should be dependent on the estimated glomerular filtration rate (eGFR).
  
  
  METHODS
  The serum κ/λ free light chain ratio, eGFR, serum M-protein and Bence Jones protein were measured in 544 patients for whom Bence Jones protein analysis was ordered.
  
  
  RESULTS
  In the population of patients without Bence Jones proteinuria or a M-protein (n = 402), there is no gradual increase in κ/λ free light chain ratio with diminishing eGFR. The κ/λ free light chain ratio in this group was 0.56-1.86 (95% interval). With this diagnostic reference range of the κ/λ ratio, 105 of the 110 patients with Bence Jones protein could be identified correctly. Only five patients with Bence Jones proteinuria (<0.17 g/L) were missed, without diagnostic or therapeutic consequences. In 36 patients (6.6%), an abnormal κ/λ free light chain ratio was measured without the presence of Bence Jones proteinuria.
  
  
  CONCLUSIONS
  A κ/λ free light chain ratio in serum can be used safely and efficiently to select urine samples which should be analysed for Bence Jones proteinuria with an electrophoresis/immunofixation technique. Using this diagnostic reference range, the number of urine samples which should be analysed by electrophoresis/immunofixation could be reduced by 74%. The diagnostic reference interval can be determined best in a group of patients for whom Bence Jones analysis is indicated. For calculation of this reference range, the eGFR value does not need to be taken into account.
authors.affiliation: Department of Clinical Chemistry and Haematology, Rijnstate Hospital, Arnhem, the Netherlands.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Schmidt-Hieltjes
authors.affiliation: Department of Clinical Chemistry and Haematology, Rijnstate Hospital, Arnhem, the Netherlands.
authors.forename: Clemens
authors.initials: C
authors.lastname: Elshof
authors.affiliation: Department of Clinical Research, Rijnstate Hospital, Arnhem, the Netherlands.
authors.forename: Lian
authors.initials: L
authors.lastname: Roovers
authors.affiliation: Department of Clinical Chemistry and Haematology, Rijnstate Hospital, Arnhem, the Netherlands.
authors.forename: Janneke
authors.initials: J
authors.lastname: Ruinemans-Koerts
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001536:Bence Jones Protein / Q000652:urine*; D015415:Biomarkers; D005260:Female; D005919:Glomerular Filtration Rate; D006023:Glycoproteins / Q000097:blood; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000097:blood*; D007146:Immunoglobulin lambda-Chains / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000175:diagnosis* / Q000209:etiology; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D006023:Glycoproteins; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; C023587:protein M (glycoprotein); D001536:Bence Jones Protein
keywords: Bence Jones protein; estimated glomerular filtration rate; screening; κ/λ free light chain ratio