title: The value of estimated GFR in comparison to measured GFR for the assessment of renal function in adult patients with Fabry disease.
abstract: BACKGROUND
  Renal disease is one of the major complications in Fabry disease, an X-linked lysosomal storage disease due to deficiency of the enzyme alpha-galactosidase A. The aim of our study was to determine the value of creatinine-, cystatin C- and beta-trace-based formulas for the estimation of glomerular filtration rate (eGFR) in Fabry patients. For comparison, the gold standard method (125)I-labelled iothalamate/(131)I-labelled hippuran [measured GFR (mGFR)] was used.
  
  
  METHODS
  GFR was estimated by using 11 different formulas based on creatinine, cystatin C and beta-trace protein. Accuracy and precision, detection of early decline of renal function and follow-up of renal function by eGFR was compared to mGFR.
  
  
  RESULTS
  One hundred and thirty-six GFR measurements and plasma samples were available from 36 (20 male) Fabry patients, treated with agalsidase alpha or beta with a median follow-up of 3.1 (range 1.5-5.2) years. Median mGFR was 97.3 (15.5-148.6) ml/min/1.73 m(2) in males and 84.4 (23.0-131.0) ml/min/1.73 m(2) in females at the start of follow-up.
  
  
  CONCLUSIONS
  Although none of the investigated endogenous markers proved to be an equivalent substitute for mGFR in Fabry patients, the Stevens equation, a creatinine- and cystatin C-based formula, most closely approximated the mGFR. When a creatinine-based formula is preferred, considering that there is no standardized method available for cystatin C, the abbreviated Modification of Diet in Renal Disease (aMDRD) and the recently developed Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formulas had the best performance. In male Fabry patients, the aMDRD may overestimate GFR, especially in the higher ranges. In these cases, CKD-EPI may perform better.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Saskia M
authors.initials: SM
authors.lastname: Rombach
authors.forename: Marije C
authors.initials: MC
authors.lastname: Baas
authors.forename: Ineke J M
authors.initials: IJ
authors.lastname: ten Berge
authors.forename: Raymond T
authors.initials: RT
authors.lastname: Krediet
authors.forename: Frederike J
authors.initials: FJ
authors.lastname: Bemelman
authors.forename: Carla E M
authors.initials: CE
authors.lastname: Hollak
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood; D000795:Fabry Disease / Q000097:blood / Q000503:physiopathology*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000097:blood; D007668:Kidney / Q000503:physiopathology*; D007677:Kidney Function Tests / Q000379:methods*; D054834:Lipocalins / Q000097:blood; D008297:Male; D008875:Middle Aged; D013261:Sterols / Q000652:urine; D055815:Young Adult
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D054834:Lipocalins; D013261:Sterols; C040164:hippurin; D003404:Creatinine; D019746:Intramolecular Oxidoreductases; C022466:prostaglandin R2 D-isomerase