title: Interfering parameters in the determination of urinary globotriaosylceramide (Gb3) in patients with chronic kidney disease.
abstract: BACKGROUND
  Globotriaosylceramide (Gb3, CD77) represents a pivotal part of the cell membrane. Measuring the urinary Gb3 content can be used to screen patients with chronic kidney disease (CKD) for Fabry disease, a disorder caused by hampered Gb3 degradation. However, little is known about factors influencing urinary Gb3 excretion other than Fabry disease. The aim of the present study was to identify routine diagnostic parameters as predictors of urinary Gb3 excretion in patients with CKD.
  
  
  METHODS
  Our study included 609 subjects with CKD stage I-V. We analyzed the influence of age, gender, renal function, urinary cell content and chemical characteristics on urinary Gb3 concentrations (total Gb3, Gb3-24 isoform, and Gb3-24:18 isoform ratio), determined by direct electrospray ionization mass spectrometry.
  
  
  RESULTS
  In 609 subjects the median total urinary Gb3 was 233 ng/mg and the Gb3-24:18 isoform ratio was 1.2. Twenty-one patients, none of whom had Fabry disease, had a Gb3-24:18 isoform ratio ≥2.3. Females excreted a higher total amount of Gb3, but the Gb3-24:18 isoform ratio was comparable to males. Renal function and age had no influence on total Gb3, Gb3 isoforms or the ratio. Only a distinct load of bacteria and leukocytes was associated with an increased Gb3 excretion. Urinary leukocytes, erythrocytes, bacteria, or protein content did not affect the Gb3-24:18 isoform ratio.
  
  
  CONCLUSIONS
  The Gb3-24:18 isoform ratio is unaffected by several potential influencing variables and may thus be applied for screening for Fabry disease in unselected cohorts of patients presenting with CKD.
authors: Department of Medicine III, Division of Nephrology and Dialysis, Medical University Vienna, Vienna, Austria. martina.gaggl@meduniwien.ac.at.
authors: Martina
authors: M
authors: Gaggl
authors: Department of Medicine III, Division of Nephrology and Dialysis, Medical University Vienna, Vienna, Austria.
authors: Marlene
authors: M
authors: Hofer
authors: Department of Medicine III, Division of Nephrology and Dialysis, Medical University Vienna, Vienna, Austria.
authors: Stefanie
authors: S
authors: Weidner
authors: Department of Medicine III, Division of Nephrology and Dialysis, Medical University Vienna, Vienna, Austria.
authors: Julia
authors: J
authors: Kleinert
authors: Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University Graz, Graz, Austria.
authors: Günter
authors: G
authors: Fauler
authors: Department of Internal Medicine IV, Section of Nephrology, Klinikum Wels-Grieskirchen, Wels, Austria.
authors: Manfred
authors: M
authors: Wallner
authors: Renal Research Institute, New York, NY, USA.
authors: Peter
authors: P
authors: Kotanko
authors: Department of Pediatrics, Medical University Graz, Graz, Austria.
authors: Eduard
authors: E
authors: Paschke
authors: Department of Medicine III, Division of Nephrology and Dialysis, Medical University Vienna, Vienna, Austria.
authors: Gere
authors: G
authors: Sunder-Plassmann
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D058491:Bacterial Load; D015415:Biomarkers / Q000652:urine; D003404:Creatinine / Q000097:blood / Q000652:urine; D000795:Fabry Disease / Q000175:diagnosis / Q000652:urine*; D005260:Female; D006417:Hematuria / Q000652:urine; D006801:Humans; D007962:Leukocytes; D008297:Male; D008875:Middle Aged; D009261:Nail-Patella Syndrome; D009394:Nephritis, Hereditary; D020033:Protein Isoforms / Q000652:urine; D051436:Renal Insufficiency, Chronic / Q000503:physiopathology / Q000652:urine*; D012737:Sex Factors; D014281:Trihexosylceramides / Q000652:urine*; D014556:Urine / Q000166:cytology / Q000382:microbiology
chemical_list: D015415:Biomarkers; D020033:Protein Isoforms; D014281:Trihexosylceramides; C018549:globotriaosylceramide; D003404:Creatinine
keywords: Chronic kidney disease; Fabry disease; Globotriaosylceramide; Lysosomal storage disorder