Limitations of Kt/V

  • Kt/V overestimates dialysis adequacy in thin, malnourished patients and elderly females due to sarcopenia and a low ‘V’. This may lead to under-dosing of dialysis. Kt corrected for body surface area may be a more accurate measure of dialysis dose in these patients.
  • There is a high index of error related to inaccurate post-dialysis BUN measurement.
  • Single treatment may not represent other treatments ( missed or shortened)
  • spKt/V or eKt/V is not applicable to daily or nocturnal dialysis. It is useful only for conventional 3 times a week intermittent hemodialysis.
  • Kt/V is a marker only of urea clearance and not of other toxic/uremic solutes that exist.
  • Other uremic toxins such as phosphate, β2 microglobulin, guanidino compounds etc. do not follow the same hemodialysis kinetics as urea and therefore their clearances are not accurately reflected by Kt/Vurea.1
  • A high Kt/V(>1.4) has not been shown to predict better survival in any randomized controlled studies (e.g. HEMO study2).This implies that there are other determinants of poor survival in hemodialysis patients besides urea clearance and that despite a high dialysis urea clearance (Kt/V), patients may retain other toxic solutes that ultimately are equally or more important than urea in influencing prognosis on dialysis.3
  • Despite these controversies surrounding KT/Vurea, it remains the most frequently used parameter for determining dialysis adequacy and its routine monitoring may help to identify problems of dialysis delivery such as access recirculation etc.


  1. Comparing the urea reduction ratio and the urea product as outcome-based measures of hemodialysis dose. AU Li Z, Lew NL, Lazarus JM, Lowrie EG SOAm J Kidney Dis. 2000;35(4):598.
  2. Eknoyan G, Beck, GJ Cheung AK, et al. Effect of dialysis dose and membrane flux in maintenance hemodialysis. N Engl J Med 2002; 347:2010.
  3. Meyer TW,Sirich TL,Fong KD et al. Kt/Vurea and non urea small solute levels in the hemodialysis study. JASN 2016;27:3469