Síndrome nefrótico

The Nephrotic Syndrome Roberto Gordillo and Adrian Spitzer Pediatr. Rev. 2009;30;94-105 DOI: 10.1542/pir.30-3-94

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Pediatrics in Review is the official journal of the American Academy of Pediatrics. A monthlypublication, it has been published continuously since 1979. Pediatrics in Review is owned, published, and trademarked by the American Academy of Pediatrics, 141 Northwest Point Boulevard, Elk Grove Village, Illinois, 60007. Copyright © 2009 by the American Academy of Pediatrics. All rights reserved. Print ISSN: 0191-9601. Online ISSN: 1526-3347.

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Article nephrology

The Nephrotic Syndrome
Roberto Gordillo, MD,* Adrian Spitzer, MD†

Objectives
1. 2. 3. 4. 5. 6. 7.

After completing this article, readers should be able to:

Author Disclosure Drs Gordillo and Spitzer have disclosed no financial relationships relevant to this article. This commentary does not contain adiscussion of an unapproved/ investigative use of a commercial product/device.

Explain the mechanism and the consequences of proteinuria. Make a presumptive diagnosis of minimal-change nephrotic syndrome. Interpret the signs associated with steroid resistance. Ascertain the timing and the indications for a kidney biopsy. Gauge the indications for referral to a pediatric nephrologist. Determine theadequacy of the therapy. Predict the disease course.

Introduction
The word “nephrosis” was introduced in the medical literature at the beginning of the 20th century in an attempt to distinguish diseases of the kidney characterized by exudation and proliferation from those characterized by inflammation (nephritis). As it became apparent that this is not a single disease, not even a group ofrelated diseases, the term “nephrosis” was supplanted by “nephrotic syndrome.” The clinical features that characterize the nephrotic syndrome result from alterations of the glomerular capillary wall and consist of heavy proteinuria and hypoalbuminemia, often associated with edema and generalized hyperlipidemia.

Pathophysiology
Proteinuria and Hypoalbuminemia

Abbreviations
ACE: BSA: CNF: CNS:FSGS: HDL: Ig: IL: ISKDC: LDL: MCNS: MN: MPGN: RAA: SLE: UPr/Cr: VLDL: angiotensin-converting enzyme body surface area congenital nephrotic syndrome of the Finnish type congenital nephrotic syndrome focal segmental glomerulosclerosis high-density lipoprotein immunoglobulin interleukin International Study of Kidney Disease in Children low-density lipoprotein minimal-change nephrotic syndromemembranous nephropathy mesangioproliferative glomerulonephritis renin-angiotensin-aldosterone systemic lupus erythematosus urine protein/creatinine ratio very low-density lipoprotein

Proteinuria is the result of alterations in the integrity of the glomerular filtration barrier. This barrier is composed of three layers in series: the fenestrated endothelium, the glomerular basement membrane, and thevisceral glomerular epithelium, comprised of podocytes and their slit diaphragms. Podocyte is the name of the epithelial cell, and foot process is the segment of the cell that extends into the urinary space. (In the nephrotic syndrome, there is effacement of the foot process, but the rest of the cell usually is preserved.) Endothelial cells have numerous openings that are 70 to 100 nm in diameter,called fenestrae, which form a physical barrier for passage of macromolecules from plasma into the renal tubule. Electron microscopic studies led to the identification of negatively charged particles (heparan sulfate proteoglycans) in the glomerular basement membrane, which preclude the passage of anionic macromolecules, such as albumin. Removal of these charges in animals by in situ perfusion of...