Domain of Adequacy of HD3.5

By definition, enhanced or frequent therapies eliminate the 48-hour non-dialytic period of thrice weekly conventional HD and provide a dose superior to the latter.  The domain of adequacy of enhanced therapies will be defined as a standard Kt/V (stdKt/V) > 2.2 and a minimal frequency of 3.5 times per week or every other day (HD3.5).

Domain of adequacy of enhanced therapies and derivation of minimal HD3.5 dose (1)

The figure portrays the domain of enhanced therapies based on the relationship of weekly stdKt/V and eKt/V for each HD session.  In order to maintain a weekly stdKt/V above 2.2, the minimal individual dose for HD3.5 is eKt/V ~ 0.8.  For practical purposes, this relationship precludes the use of short HD3.5 sessions.


  1. Gotch F, Keen M. Kinetic modeling in hemodialysis. In: Nissenson AR, Fine RN, eds. Clinical Dialysis. 4th ed. New York: McGraw-Hill Medical Publication; 2005:153-202.