As kidney disease is life threatening, frequent dialysis is essential for survival. Anyhow the treatment itself takes a lot of space in patients’ lives. Whilst the clinical outcome was the target of therapy optimization, the focus switched lately towards consideration of quality of life at the patients as an indicator for successful therapy. Individualized treatment is possible when the processes in the human body during therapy are understood holistically. Although mathematic models of the processes exist, prediction is often far from reality. Through understanding and identification of input factors into a circuit model as well as the adaptation of output parameters to the shift of target therapy focus, it is possible to substitute existing models. Goal of this research is therefore the definition of a circuit model and definition of influencing factors to improve the simulation of therapy process in the human body.