The role of the kidney in protein metabolism: the capacity of tubular lysosomal proteolysis in nephrotic syndrome.

The kidneys play an important role in protein metabolism. Renal tubules reabsorb 3 g of albumin under normal conditions, and exhibit a 6-fold increase in the reabsorption of albumin in patients with focal segmental glomerulosclerosis. The capacity of tubular lysosomal proteolysis can be increased up to 8-fold; however, proteinuria over the capacity of tubular handling may cause tubulointerstitial damage in patients with nephrotic syndrome.