Nephrotic Syndrome
Although not a disease in itself, nephrotic syndrome is characterized by marked proteinuria, hypoalbuminemia, hyperlipidemia, and edema. It results from a glomerular defect that affects the vessels’ permeability and indicates renal damage. The prognosis is highly variable, depending on the underlying cause, but age plays no part in progression or prognosis. Some forms of nephrotic syndrome may eventually progress to end-stage renal failure.
Causes
About 75% of nephrotic syndrome cases result from primary (idiopathic) glomerulonephritis. Other causes of nephrotic syndrome include:
Lipid nephrosis (nil lesions) exhibits normal glomeruli by light microscopy. Some tubules may contain increased lipid deposits.
Membranous glomerulonephritis is the most common lesion in adult idiopathic nephrotic syndrome. It’s characterized by the appearance of immune complexes, seen as dense deposits, within the glomerular basement membrane and by the uniform thickening of the basement membrane. It eventually progresses to renal failure.
Focal glomerulosclerosis can develop spontaneously at any age, can occur after kidney transplantation, or can result from heroin injection. Up to 20% of adults with nephrotic syndrome develop this condition. Lesions initially affect some of
the deeper glomeruli, causing hyaline sclerosis. Involvement of the superficial glomeruli occurs later. These lesions usually cause slowly progressive deterioration in renal function, although remissions may occur in children.
Membranoproliferative glomerulonephritis causes slowly progressive lesions to develop in the subendothelial region of the basement membrane.
Pediatric pointerThis disorder may follow infection, particularly streptococcal infection, and occurs primarily in children and young adults.
Other causes of nephrotic syndrome include allergic reactions, pregnancy, hereditary nephritis, neoplastic diseases such as multiple myeloma, metabolic diseases such as diabetes mellitus, and collagen-vascular disorders such as systemic lupus erythematosus.
Circulatory diseases, such as heart failure, sickle cell anemia, and renal vein thrombosis; exposure to nephrotoxins, such as mercury and gold; and infections, such as tuberculosis and enteritis may also result in nephrotic syndrome.
Glomerulonephritis of any type increases glomerular protein permeability, which leads to increased urinary excretion of protein (especially albumin) and subsequent hypoalbuminemia.
Complications
Major complications include malnutrition, infection, coagulation disorders, hypovolemia, thromboembolic vascular occlusion (especially in the lungs and legs), and accelerated atherosclerosis. Hypochromic anemia can develop from excessive urinary excretion of transferrin. Acute renal failure may occur and may progress to end-stage renal disease.
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