title: Extracellular fluid volume and glomerular filtration rate in 1878 healthy potential renal transplant donors: effects of age, gender, obesity and scaling.
abstract: Aim. The aim of this study was to investigate the influence of age, gender, obesity and scaling on glomerular filtration rate (GFR) and extracellular fluid volume (ECV) in healthy subjects.
  
  
  METHODS
  This is a retrospective multi-centre study of 1878 healthy prospective kidney transplant donors (819 men) from 15 centres. Age and body mass index (BMI) were not significantly different between men and women. Slope-intercept GFR was measured (using Cr-51-EDTA in 14 centres; Tc-99m-DTPA in one) and scaled to body surface area (BSA) and lean body mass (LBM), both estimated from height and weight. GFR was also expressed as the slope rate constant, with one-compartment correction (GFR/ECV). ECV was measured as the ratio, GFR to GFR/ECV.
  
  
  RESULTS
  ECV was age independent but GFR declined with age, at a significantly faster rate in women than men. GFR/BSA was higher in men but GFR/ECV and GFR/LBM were higher in women. Young women (<30 years) had higher GFR than young men but the reverse was recorded in the elderly (>65 years). There was no difference in GFR between obese (BMI>30 kg/m2) and non-obese men. Obese women, however, had lower GFR than non-obese women and negative correlations were observed between GFR and both BMI and %fat. The decline in GFR with age was no faster in obese versus non-obese subjects. ECV/BSA was higher in men but ECV/LBM was higher in women. ECV/weight was almost gender independent, suggesting that fat-free mass in women contains more extracellular water. BSA is therefore a misleading scaling variable.
  
  
  CONCLUSIONS
  There are several significant differences in GFR and ECV between healthy men and women.
authors.affiliation: Department of Nuclear Medicine, Royal Sussex County Hospital, Brighton, UK. a.m.peters@bsms.ac.uk
authors.forename: A Michael
authors.initials: AM
authors.lastname: Peters
authors.forename: Laura
authors.initials: L
authors.lastname: Perry
authors.forename: Claire A
authors.initials: CA
authors.lastname: Hooker
authors.forename: Bethany
authors.initials: B
authors.lastname: Howard
authors.forename: Mark D J
authors.initials: MD
authors.lastname: Neilly
authors.forename: Nagabhushan
authors.initials: N
authors.lastname: Seshadri
authors.forename: Ravin
authors.initials: R
authors.lastname: Sobnack
authors.forename: Andrew
authors.initials: A
authors.lastname: Irwin
authors.forename: Hayley
authors.initials: H
authors.lastname: Snelling
authors.forename: Thomas
authors.initials: T
authors.lastname: Gruning
authors.forename: Neva H
authors.initials: NH
authors.lastname: Patel
authors.forename: Richard S
authors.initials: RS
authors.lastname: Lawson
authors.forename: Gregory
authors.initials: G
authors.lastname: Shabo
authors.forename: Nigel
authors.initials: N
authors.lastname: Williams
authors.forename: Surendra
authors.initials: S
authors.lastname: Dave
authors.forename: Mark C
authors.initials: MC
authors.lastname: Barnfield
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D002860:Chromium Radioisotopes; D045604:Extracellular Fluid / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007677:Kidney Function Tests; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D011379:Prognosis; D011446:Prospective Studies; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D012737:Sex Factors; D014019:Tissue Donors
chemical_list: D002860:Chromium Radioisotopes