Definition

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.

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. 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

Risk Factors

Tell your doctor if you have any of the following factors that increase your risk of nephrotic syndrome:

  • Diabetes
  • Lupus
  • Exposure to drugs or toxins
  • Certain infections

Symptoms

Symptoms may include:

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

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. High blood pressure may indicate kidney damage. A urine test will show if you have too much protein or any blood in your urine. A blood test will show if your blood contains too much cholesterol and not enough protein.

Your bodily fluids and tissues may be tested. This can be done with:

  • Blood tests
  • Urine tests
  • Biopsy

Images may need to be taken of your bodily structures. This can be done with:

If your doctor suspects nephrotic syndrome, you may be referred to a kidney specialist.

Treatment

Treatment depends on what is causing the nephrotic syndrome. Some cases are treatable with medicine, while others lead to kidney failure despite treatment. The underlying cause will be treated, if possible. Steps will be taken to:

  • Adjust your 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, also known as water pills
  • Lower cholesterol and blood pressure with diet, exercise, and medicines

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.