title: Indexing glomerular filtration rate to body surface area: clinical consequences.
abstract: BACKGROUND
  Kidney function is mostly expressed in terms of glomerular filtration rate (GFR). A common feature is the expression as ml/min per 1.73 m(2) , which represents the adjustment of the individual kidney function to a standard body surface area (BSA) to allow comparison between individuals. We investigated the impact of indexing GFR to BSA in cancer patients, as this BSA indexation might affect the reported individual kidney function.
  
  
  METHODS
  Cross-sectional study of 895 adults who had their kidney function measured with (51) chrome ethylene diamine tetraacetic acid. Mean values of BSA-indexed GFR vs. mean absolute GFR were analyzed with a t-test for paired data. Bland-Altman plot was used to analyze agreement between the indexed and absolute GFR values.
  
  
  CONCLUSIONS
  BSA-GFR in patients with a BSA <1.60 m(2) overestimated GFR with a bias of 10.08 ml/min (11.46%) and underestimated GFR in those with a BSA >2 m(2) with a bias up to -20.76 ml/min (-23.59%). BSA is not a good normalization index (NI) in patients with extreme body sizes. Therefore, until a better NI is found, we recommend clinicians to use the absolute GFR to calculate individual drug chemotherapy dosage as well as express individual kidney function.
authors.affiliation: Department of Nephrology, Roskilde University Hospital, University of Copenhagen, Roskilde, Denmark.
authors.forename: Belén
authors.initials: B
authors.lastname: Redal-Baigorri
authors.forename: Knud
authors.initials: K
authors.lastname: Rasmussen
authors.forename: James Goya
authors.initials: JG
authors.lastname: Heaf
mesh_terms: D000328:Adult; D001830:Body Surface Area; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012015:Reference Standards
keywords: body weights and measures; drug dosage calculations; indexed glomerular filtration rate; kidney function tests; radioisotope diagnostic techniques