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Overview of heavy proteinuria and the nephrotic syndrome

Authors
Ellie Kelepouris, MD, FAHA
Brad H Rovin, MD
Section Editor
Richard J Glassock, MD, MACP
Deputy Editor
Albert Q Lam, MD

INTRODUCTION AND TERMINOLOGY

Diseases of the glomerulus can result in three different urinary and clinical patterns: focal nephritic; diffuse nephritic; and nephrotic. (See "Differential diagnosis and evaluation of glomerular disease".)

Mild nephritic – Disorders resulting in a mild nephritic sediment are generally associated with inflammatory lesions in less than one-half of glomeruli on light microscopy (focal glomerulonephritis). The urinalysis reveals red cells (which often have a dysmorphic appearance), occasionally red cell casts, and mild proteinuria (usually less than 1.5 g/day). The findings of more advanced disease are usually absent, such as heavy proteinuria, edema, hypertension, and renal insufficiency. These patients often present with asymptomatic hematuria and proteinuria discovered on routine examination or, occasionally, with episodes of gross hematuria.

Severe nephritic – The urinalysis in diffuse glomerulonephritis is similar to focal disease, but heavy proteinuria (which may be in the nephrotic range), edema, hypertension, and/or renal insufficiency may be observed. Diffuse glomerulonephritis affects most or all of the glomeruli.

Nephrotic – The nephrotic sediment is associated with heavy proteinuria and lipiduria, but few cells or casts. The term "nephrotic syndrome" refers to a distinct constellation of clinical and laboratory features of renal disease. It is specifically defined by the presence of heavy proteinuria (protein excretion greater than 3.5 g/24 hours), hypoalbuminemia (less than 3 g/dL), and peripheral edema. Hyperlipidemia and thrombotic disease are also frequently observed.

Isolated heavy proteinuria without edema or other features of the nephrotic syndrome is suggestive of a glomerulopathy (with the same etiologies as the nephrotic syndrome), but is not necessarily associated with the multiple clinical and management problems characteristic of the nephrotic syndrome. This is an important clinical distinction because heavy proteinuria in patients without edema or hypoalbuminemia is more likely to be due to secondary focal segmental glomerulosclerosis (FSGS) (due, for example, to diabetes) [1].

                            

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Literature review current through: Nov 2016. | This topic last updated: Tue Jul 05 00:00:00 GMT 2016.
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