 Session-to-session variations in delivered KtV that may cause failure to achieve the prescribed dialysis dose may be significant in regular clinical practice. To date, this is not recognized due to monthly blood KtV measurements only. Suboptimal delivery of prescribed dialysis dose may be caused by low effective treatment time, vascular access dysfunction, hemodynamic stability, blood pump speed, membrane influences, lab value variability or others which may vary from session to session. Patients close to recommended target limits of dialysis dose may thus be randomly attributed to be adequately or inadequately dialyzed. Therefore, in the literature, use of average KtV values is recommended. 