Nephrotic Syndrome

Published on 21/03/2015 by admin

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Last modified 21/03/2015

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Chapter 53 Nephrotic Syndrome


Nephrotic syndrome is the clinical state in which the glomerular membrane has an increased permeability to plasma proteins. This leads to severe edema, proteinuria, and hypoalbuminemia. The loss of protein from the vascular space causes decreased plasma osmotic pressure and increased hydrostatic pressure, resulting in the accumulation of fluids in interstitial spaces and the abdominal cavity. The decrease in vascular fluid volume stimulates the renin-angiotensin system, resulting in secretion of antidiuretic hormone (ADH) and aldosterone. Tubular resorption of sodium (Na+) and water is increased, expanding the intravascular volume. This fluid retention leads to increased edema as retained fluid shifts into the interstitial space. Coagulation and venous thrombosis may occur as a result of decreased vascular volume, which causes hemoconcentration and urinary loss of coagulation proteins. Loss of immunoglobulins through the glomerular membrane can lead to increased susceptibility to infection. Hyperlipidemia is believed to occur because of increased synthesis of lipoproteins in response to low plasma oncotic pressure.

Nephrotic syndrome is the pathologic outcome of various factors that alter glomerular permeability. The causes of nephrotic syndrome can be categorized into primary (idiopathic) and secondary (Box 53-1). Primary nephrotic syndrome is divided into three histologic groups: minimal-change nephrotic syndrome (MCNS), focal segmental glomerulosclerosis (FSGS), and membranous neuropathy (rare in children). Based on clinical classification, the syndrome types differ according to the course of the disease, treatment, and prognosis. It is considered a chronic illness because of the occurrence of relapses. Many children will have five or more relapses over the course of the disease. A child is considered to have frequently relapsing nephrotic syndrome if there are two or more relapses within the first 6 months and/or four or more relapses within a 12-month period. The frequency of relapse decreases over time and becomes relatively rare by adolescence.