Nephrotic syndrome (or nephrosis) is characterized by marked proteinuria, hypoalbuminemia, hyperlipemia, and edema. Although nephrotic syndrome isn’t a disease itself, it results from a specific glomerular defect and indicates renal damage. The prognosis is highly variable, depending on the underlying cause. Some forms may progress to end-stage renal failure.
About 75% of nephrotic syndrome cases result from primary (idiopathic) glomerulonephritis. Classifications include the following:
With minimal change disease (lipid nephrosis or nil disease)—the main cause of nephrotic syndrome in children—the glomeruli appear normal by light microscopy. Some tubules may contain increased lipid deposits.
Membraneous glomerulonephritis—the most common lesion in patients with adult idiopathic nephrotic syndrome—is characterized by uniform thickening of the glomerular basement membrane containing dense deposits. It can eventually progress to renal failure.
Focal glomerulosclerosis can develop spontaneously at any age, follow kidney transplantation, or result from heroin abuse. Lesions initially affect the deeper glomeruli, causing hyaline sclerosis, with later involvement of the superficial glomeruli. These lesions generally cause slowly progressive deterioration in renal function. Remissions occur occasionally.
With membranoproliferative glomerulonephritis, slowly progressive lesions develop in the subendothelial region of the basement membrane. These lesions may follow infection, particularly streptococcal infection. This disease occurs primarily in children and young adults.