**4.6 Hemodialysis dose**

Quantifying removal of toxic uremic solutes is important to assess the adequacy of HD. The delivered dialysis dose is a function of length of the session (*t*), dialysate and blood flow rates, volume of distribution (V) of the uremic toxin studied, and the dialyzer efficiency (*K*o*A*). Volume of distribution is very different for urea (total body water volume), than other small-molecular-weight. The minimum frequency and dosage of dialysis is three times per week, for a minimum treatment time of 3 to 4 hours, a blood flow rate of at least 250 ml/min, and a dialysate flow rate of 500 to 800 ml/min. Patients that are initiated on HD, *V* is unknown and has to be estimated (men, 58% of body weight; women, 55% of body weight). After obtaining measured *Kt/V* the dialysis prescription can be adjusted to meet the *Kt/V* goals. For patients with severe and long-standing uremia, it's recommended to provide several sessions in achieving target dose to avoid the dialysis disequilibrium syndrome.
