Nephrotic syndrome happens when the kidneys let protein leak into the urine. When this happens, there is not enough protein in the blood. Low protein in the blood allows fluid to leak out of the blood stream and into body tissues.

Nephrotic syndrome is a collection of the following signs:

  • High protein in the urine
  • Low protein in the blood
  • Swelling of body tissues
  • High cholesterol in the blood

Nephrotic syndrome is not a disease itself. It is a set of signs and symptoms that indicate that another disease has damaged the kidneys, and that they are no longer working properly.

Nephrotic syndrome is caused by damage to tiny filters in the kidneys, called glomeruli. The glomeruli filter waste and excess water from the blood. This forms urine, which reaches the bladder via the ureters. Diseases that damage the glomeruli cause nephrotic syndrome.

Anatomy of the Kidney
Glomerulonephritis
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Diseases that may lead to nephrotic syndrome include:

  • Glomerulonephritis—inflammation of the glomeruli from infection or other causes
  • Diabetic nephropathy—kidney complications from diabetes
  • Membranous nephropathy
  • IgA nephropathy
  • Membranoproliferative glomerulonephritis
  • Renal amyloidosis—abnormal protein deposits in the kidneys
  • Minimal change disease
  • Other diseases, including systemic lupus erythematosus, certain infections, toxins, drugs, allergic reactions, sickle cell disease, renal vein thrombosis, and some types of cancer