Renal Loss of Function

In renal insufficiency, the number of functional nephrons is reduced. In order to nevertheless achieve sufficient filtration performance, the kidney increases the effective filtration pressure in the residual nephrons (hyperfiltration). The increase of the eff. filtration pressure is essentially caused by an angiotensin II-induced constriction of the efferens vas in the sense of hyperfiltration. However, hyperfiltration accelerates the further sclerotic alteration of these remaining glomerules and thus the progression of renal insufficiency. The reduction of the eff. filtration pressure initially leads to a slight increase of the serum creatinine values, but is later compensated by the improved renal perfusion.