• What is Nephrotic Syndrome?

• What diseases cause Nephrotic Syndrome?

• Summary

• Renal Pathology Tutorial

 

 

What is Nephrotic Syndrome?

NEPHROTIC SYNDROME is a condition resulting from increased leakage of protein into the urine (proteinuria) from the filters in the kidneys (glomeruli) that produce urine from blood. With the loss of protein in the urine, changes occur in the blood that cause fluid to accumulate in the tissues of your body.  This results in tissue swelling (EDEMA).  The edema may develop in your hands and feet (making shoes or rings feel tight), ankles or in your face causing puffiness around the eyes.  In some instances, the fluid accumulates on your lungs making it more difficult to breathe. Nephrotic syndrome is caused by diseases that alter the function of the walls of the small vessels (capillaries) in the kidney filters (glomeruli) that filter blood to make urine.

Proteinuria results when there is a defect in the glomerular capillary wall that allows protein to leak into the urine.

What keeps proteins out of the urine?

The normal glomerular capillary wall keeps blood cells and most proteins in the blood. In patients with proteinuria, protein leaks across the wall into the urine. The barriers in the capillary wall that keep protein out of the urine are the endothelial cell lining the capillary lumen, the basement membrane under the endothelial cell and the cell on the outside surface of the capillary (epithelial cells). The epithelial cell (podocyte) normally has little “feet” (pods) that sit on the basement membrane and are connected by a thin membrane. The glomerular epithelial cells (podocytes) appear to be the most important barrier that prevents protein from leaking into the urine.

Drawn below are the barriers that keep protein and blood cells out of the urine. These are the endothelial cell, basement membrane and epithelial cell (podocyte). The epithelial cell (podocyte) seems to be most important. Injury to these barriers causes proteinuria and hematuria.

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What diseases cause Nephrotic Syndrome?

Many different diseases can injure glomerular capillary walls and cause proteinuria.  Some are listed below:

• Minimal change disease (most common cause in children)
• Membranous glomerulopathy (most common cause in Caucasian   
  adults)
• Focal segmental glomerulosclerosis (most common cause in African American adults)
• Diabetic glomerulosclerosis
• C1q nephropathy
• Membranoproliferative glomerulonephritis
• Amyloidosis
• Lupus nephritis

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Summary

• Nephrotic syndrome is caused by multiple glomerular diseases that cause injury to glomerular capillary walls resulting in severe leakage of proteins into the urine (proteinuria).
• A major symptom of nephrotic syndrome is swelling (edema), especially in the ankles and around the eyes.
• A renal biopsy usually is required to make a diagnosis of the specific kind of glomerular disease that is causing the nephrotic syndrome in an individual patient.

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