[The kidney and life expectancy].
Basic renal functions are physiologically determined as precisely regulated relation between more and less physical events with low energy consumption and energy dependent cellular transport mechanisms. All well in ageing as under various conditions of renal diseases adaptive processes become biologically effective, so that stabilisation of homöostasis is possible up to a loss of 95% of normal function. Life expectancy has to be defined under the new conditions of renal replacement therapy effective beyond this biologically defined border line.