Is urea kinetic modelling an appropriate tool for guiding ultrashort high-flux dialysis therapy?

High-flux dialysers are frequently used for highly efficient ultrashort treatment schedules. To avoid the risk of inadequately low dialysis dose in this treatment strategy where 'every minute counts', it is often advocated to monitor the treatment quality by means of urea kinetic modelling (UKM). However, careful computational analysis of concentration curves generated by UKM versus more realistic two-pool model curves indicates the risk of substantial overestimation of the protein catabolic rate (PCR). Therefore conventional UKM should not be used to monitor and/or guide treatment schedules with dialyser urea clearance greater than 250 ml/min and dialysis time less than 3 h. Under these conditions, PCR can be overestimated by as much as 20%.