Benjamin Dickie1, Constantina Chrysochou2, Su Wei Lim1, Philip A. Kalra2, David L. Buckley1, Steven Sourbron1
1Division of Medical Physics, University of Leeds, Leeds, Yorkshire, United Kingdom; 2Department of Renal Medicine, Salford Royal Hospital, Manchester, United Kingdom
The aim of this study was to identify the reason for the bias in single-kidney glomerular filtration rate (SK-GFR) derived from a two-compartment filtration model. Three hypotheses were investigated: (I) water reabsorption is modelled incorrectly; (II) the model is not suitable for whole-kidney curves; (III) the tubuli are not well-mixed. 64 kidneys with known Isotope SK-GFR served as a basis for comparison. The results show that hypothesis (III) explains the bias. Assuming instead a plug-flow model for the tubulus eliminates the bias and increases the precision, without compromising the quality of the fit or increasing the number of free parameters.