title: Elimination of the need for urine studies in the screening algorithm for monoclonal gammopathies by using serum immunofixation and free light chain assays.
abstract: OBJECTIVE
  To determine the relative diagnostic contribution of urine assays as part of the screening algorithm for monoclonal gammopathies.
  
  
  METHODS
  We identified 428 patients with a monoclonal gammopathy and monoclonal urinary protein at initial diagnosis of plasma cell dyscrasia who had also undergone serum immunofixation and serum free light chain quantitation within 30 days of diagnosis. The laboratory results for serum protein electrophoresis, serum immunofixation, serum free light chain, urine protein electrophoresis, and urine immunofixation were reviewed.
  
  
  RESULTS
  The patients had diagnoses of multiple myeloma, primary amyloid, monoclonal gammopathy of undetermined significance, smoldering multiple myeloma, solitary plasmacytomas, and other less frequently detected monoclonal gammopathies. All 428 had a monoclonal urine protein, 85.7% had an abnormal serum free light chain kappa/lambda ratio, 80.8% had an abnormal serum protein electrophoresis, and 93.5% had an abnormal serum immunofixation result. All 3 serum assays were normal in only 2 patients, 1 of whom had monoclonal gammopathy of undetermined significance (idiopathic Bence Jones proteinuria) and 1 whose urine sample contained an intact monoclonal immunoglobulin but whose serum and subsequent urine samples showed no evidence of a monoclonal gammopathy.
  
  
  CONCLUSIONS
  Discontinuation of urine studies and reliance on a diagnostic algorithm using only serum studies (protein electrophoresis, immunofixation, and free light chain quantitation) missed 2 (0.5%) of the 428 monoclonal gammopathies with urinary monoclonal proteins, and these 2 cases required no medical intervention.
authors.affiliation: Division of Clinical Biochemistry and Immunology, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905, USA. katzmann@mayo.edu
authors.forename: Jerry A
authors.initials: JA
authors.lastname: Katzmann
authors.forename: Angela
authors.initials: A
authors.lastname: Dispenzieri
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kyle
authors.forename: Melissa R
authors.initials: MR
authors.lastname: Snyder
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Plevak
authors.forename: Dirk R
authors.initials: DR
authors.lastname: Larson
authors.forename: Roshini S
authors.initials: RS
authors.lastname: Abraham
authors.forename: John A
authors.initials: JA
authors.lastname: Lust
authors.forename: L Joseph
authors.initials: LJ
authors.lastname: Melton
authors.forename: S Vincent
authors.initials: SV
authors.lastname: Rajkumar
mesh_terms: D000465:Algorithms; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D004586:Electrophoresis; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood* / Q000652:urine; D010265:Paraproteinemias / Q000097:blood / Q000175:diagnosis* / Q000652:urine; D011507:Proteinuria; D016482:Urinalysis / Q000706:statistics & numerical data
chemical_list: D007147:Immunoglobulin Light Chains