title: Day-to-day variability in glomerular filtration rate in normal dogs by scintigraphic technique.
abstract: The sources of variability in variability of scintigraphic measurements of glomerular filtration rate (GFR) have not been determined. The day to day variability of GFR was studied in 18 healthy beagle dogs. The renal uptake of 99mTc-diethylenetriaminepentaacetic acid (DTPA) of each dog was measured using a scintigraphic technique three times at intervals of 5-26 days. GFR was calculated from a regression equation relating uptake to plasma clearance, derived in our laboratory. The mean GFR was 3.97 +/- 0.72 (SD) ml/min/kg with values from 2.66 to 5.67 ml/min/kg. Analysis of variance (ANOVA) using a linear mixed model showed that most variability is a result of the dogs, less because of day to day variability and very little to the measurement variability. The repeatability coefficients for the day to day variability and measurement variability were 1.06 and 0.21 ml/min/kg respectively. The day to day variability can be caused by physiological homeostatic adjustments by the kidneys needed because of fluctuations in food and fluid intake, each dog's individual capacity to adjust, and to intrinsic errors in the measurement method. These results should be considered when using the scintigraphic method for clinical evaluation and research.
authors.affiliation: Department of Clinical Radiology, Facility of Veterinary Medicine, University of Agricultural Sciences, Uppsala, Sweden. naruepon.kampa@klra.slu.se
authors.forename: N
authors.initials: N
authors.lastname: Kampa
authors.forename: I
authors.initials: I
authors.lastname: Boström
authors.forename: P
authors.initials: P
authors.lastname: Lord
authors.forename: U
authors.initials: U
authors.lastname: Wennstrom
authors.forename: P
authors.initials: P
authors.lastname: Ohagen
authors.forename: E
authors.initials: E
authors.lastname: Maripuu
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D004285:Dogs / Q000502:physiology*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology / Q000662:veterinary*; D007668:Kidney / Q000000981:diagnostic imaging / Q000502:physiology*; D008297:Male; D015588:Observer Variation; D011877:Radionuclide Imaging / Q000662:veterinary; D012016:Reference Values; D016284:Technetium Tc 99m Pentetate
chemical_list: D016284:Technetium Tc 99m Pentetate