title: Measuring glomerular filtration rate using 51Cr-EDTA: body surface area normalization before or after Bröchner-Mortensen correction?
abstract: BACKGROUND
  Guidelines for measuring glomerular filtration rate (GFR) using Cr-EDTA require normalizing of GFR for body surface area (BSA) before applying the Bröchner-Mortensen (BM) correction. The guideline explicitly mentions the importance of performing BSA normalization before BM correction and that this is particularly important in children in whom the effects of BSA normalization are largest.
  
  
  METHODS
  We theoretically showed that the order of applying BM correction and BSA indexing is indeed important for patient populations having a low BSA and a high slow GFR. We then compared the exact GFR, obtained from the double-exponential concentration-time curve in Duchenne muscular dystrophy (DMD) patients, with the GFR obtained from the slow compartment method using the BM correction.
  
  
  RESULTS
  The median GFR for the 20 DMD patients obtained from the BSA-BM order deviates 5.40% from the exact GFR (P=0.0006), whereas the median GFR obtained from the BM-BSA order deviates only -0.05% (P>0.05) from the exact GFR, resulting in a median of differences of 5.50% between the two methods (P<0.0001).
  
  
  CONCLUSIONS
  The correct order of application in this DMD population should be BM correction first, followed by BSA indexing, and not vice versa. In general, the order of applying the BM correction and BSA normalization becomes more important with increasing slow GFR and extreme low BSA. The order of application is of less importance for people with normal BSA and/or normal GFR.
authors.affiliation: Departments of aPublic Health and Primary Care at Kulak bDevelopment and Regeneration at Kulak, KU Leuven Kulak, Kortrijk Departments of cPaediatric Neurology dPaediatric Nephrology eNuclear Medicine, University Hospital Leuven Departments of fDevelopment and Regeneration gImaging and Pathology, KU Leuven, Leuven, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Pottel
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Hoste
authors.forename: Liesbeth
authors.initials: L
authors.lastname: De Waele
authors.forename: Elke
authors.initials: E
authors.lastname: Braat
authors.forename: Kristof
authors.initials: K
authors.lastname: Baete
authors.forename: Karolien
authors.initials: K
authors.lastname: Goffin
authors.forename: Elena
authors.initials: E
authors.lastname: Levtchenko
authors.forename: Olivier
authors.initials: O
authors.lastname: Gheysens
mesh_terms: D000293:Adolescent; D001830:Body Surface Area; D002648:Child; D002675:Child, Preschool; D002860:Chromium Radioisotopes; D004492:Edetic Acid; D005919:Glomerular Filtration Rate; D006801:Humans; D007677:Kidney Function Tests / Q000592:standards*; D020388:Muscular Dystrophy, Duchenne / Q000503:physiopathology; D012015:Reference Standards; D055815:Young Adult
chemical_list: D002860:Chromium Radioisotopes; D004492:Edetic Acid