Definition

Nephrotic syndrome occurs when the kidneys let protein leak into the urine. When this happens, there is too little 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 and symptoms:

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

Protein

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

This is a serious condition that requires care from your doctor. Contact your doctor if you think you may have nephrotic syndrome.

Causes

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

Anatomy of the Kidney

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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 long-standing diabetes)
• Membranous nephropathy
• Renal ]]>amyloidosis]]> (abnormal protein deposits in the kidneys)
• Minimal change disease—This usually occurs in children when nephrotic syndrome occurs, despite little or no change to the structure of glomeruli or surrounding tissue upon examination.
• Other diseases, including ]]>systemic lupus erythematosus]]> , certain infections, toxins, allergic reactions, ]]>sickle cell disease]]> , renal vein thrombosis, some types of cancer, and other diseases

Risk Factors

The following factors increase your chance of developing nephrotic syndrome. If you have any of these risk factors, tell your doctor.

• Kidney disease
• Diabetes]]>
• Lupus

Symptoms

Symptoms may include:

• Swelling around the following body parts:
  • Eyes
  • Face
  • Feet
  • Ankles
  • Hands
  • Abdomen
• Weight gain from excess fluids
• Shortness of breath
• Poor appetite
• Foamy urine
• Fatigue

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam. High blood pressure]]> may indicate kidney damage. A urine test will show if you have too much protein in your urine, and a blood test will show if your blood contains too much cholesterol and not enough protein.

Other blood tests may be performed to determine the cause of the syndrome and to assess how well the kidney is functioning. If your doctor suspects nephrotic syndrome, he or she may refer you to a nephrologist (kidney specialist).

In some cases, a ]]>biopsy]]> of the kidney is necessary to determine the cause of the syndrome and the best way to treat it. Imaging tests of the kidneys may also be useful in selected cases. These include:

• ]]>Computed tomography (CT) scan]]> —a type of x-ray that uses a computer to make pictures of structures inside the body
• ]]>Magnetic resonance imaging (MRI)]]> —a test that uses magnetic waves to make pictures of structures inside the body
• ]]>Ultrasound]]> —a test that uses sound waves to examine structures inside the body

Treatment

Treatment depends on what is causing the nephrotic syndrome. Some cases are treatable with medication, while others lead to kidney failure despite treatment. Besides directly treating the underlying cause, if possible, steps are taken to:

• Adjust diet to replace protein lost in the urine
• Use ACE inhibitors to reduce protein loss (in some cases)
• Treat edema by restricting salt intake and taking diuretics (water pills)
• Lower cholesterol and blood pressure with diet, exercise, and medications

Prevention

Most conditions that lead to nephrotic syndrome cannot be prevented. However, the risk of type 2 diabetes]]> may be reduced through exercise and weight control.