[Mechanism of proteinuria: filtration and resorption of plasma proteins].

Glomerular filtration and tubular reabsorption of endogenous serum proteins were measured using micropuncture technique in the rat kidney. Data resulting from experiments on the single nephron level are compared with human overall kidney function. Reabsorption of filtered protein was virtually complete (84 to 96%) at endogenous serum levels. Tubular reabsorption capacity is almost reached under control conditions. In human infants, tubular protein reabsorption capacity increases with maturation.