Proteasuria: The Link between Physiopathogenesis and Edema Management in Nephrotic Syndrome?

Abstract

Nephrotic syndrome is a pathology characterized by severe proteinuria, hypoalbuminemia, dyslipidemia, and edema. Edema has classically been associated with an alteration of the forces that govern Starling’s principle. However, some proteins eliminated in excess in the urine (proteasuria) can activate the epithelial sodium channel (ENaC), favoring sodium retention and edema. The α- and γ-ENaC subunits are activated by releasing inhibitory segments that favor the probability of channel opening. Some proteases that have been investigated include plasmin, prostasin, transmembrane protease serine 4, cathepsin, and neutrophil elastases. Therapeutic strategies include water and sodium restriction in the diet, appropriate dosing of diuretics (loop, thiazides, or acetazolamide), and in severe cases, mechanical ultrafiltration. Due to the continuous activation of ENaC in nephrotic syndrome, amiloride is an attractive diuretic strategy that has been shown to be effective in some patients with an acceptable safety profile.