Nephrotic Syndrome
What is it?
Nephrotic syndrome is a condition marked by the loss of large amounts of protein through the urine. A number of diseases can result in the syndrome; however, in many cases it is caused by kidney damage of unknown origin, especially in children, in whom it is most common. The syndrome arises from damage to the glomeruli, the tiny structures in the kidneys that filter blood. Small chemical substances, including waste products, pass through the glomerular membrane; most proteins are normally too large to cross an intact membrane. But if the glomeruli are damaged, proteins may escape into the urine. Loss of large amounts of protein through the urine lowers albumin levels in the blood, thus preventing fluid in the body tissues from returning to the bloodstream and partially producing the swelling (edema) characteristic of this syndrome. Swelling is exacerbated by an abnormal retention of salt by the kidneys.Major complications include protein malnutrition, massive swelling, occlusion of major veins by blood clots, and renal failure. Children with nephrotic syndrome are more vulnerable to systemic infections. The outcome depends on the underlying cause of the syndrome.
What Causes It?
- Disorders that can cause the syndrome include diabetes mellitus, systemic lupus erythematosus, amyloidosis, syphilis, hepatitis B, HIV, and cancer.
- Some toxins and medications, such as heroin, gold, mercury, lead, mesantoin, and perchlorate, can damage the kidneys.
- Allergic reactions to bee stings and poison ivy may result in nephrotic syndrome.
- The cause of many cases is unknown.
Prevention
- Treatment of potential underlying causes (such as lupus) may prevent the onset of nephrotic syndrome.
Diagnosis
- Blood tests show a reduction in albumin and an increase in triglycerides and cholesterol.
- Urine protein loss is measured. Urine is also examined for red and white blood cells.
- A kidney biopsy may be performed. Under local anesthesia a needle is inserted into the kidney through the back to extract a small tissue sample.
How to Treat It
- A low-salt diet may help reduce fluid retention.
- Diuretics are used to reduce excess fluid retention and increase urine output.
- Long-term anticoagulant treatment may be needed in those with the tendency to form blood clots.
- Antihypertensive drugs, such as ACE inhibitors (which may help decrease urine protein and prevent the loss of renal function), may be prescribed to reduce associated high blood pressure.
- Antibiotics may be needed for bacterial infections.
- Corticosteroids may reduce protein loss in the urine if no known cause is found. Usually, a kidney biopsy is performed prior to the use of this medication which has many side effects.
- Intravenous albumin may be given to increase plasma protein levels when extremely low blood albumin levels cause severe swelling. However, the albumin is rapidly excreted in the urine.
- Chemotherapeutic drugs used to treat cancer or medications used in transplant patients may be effective in preventing relapses.
When to Call a Doctor
- Call a doctor for symptoms of nephrotic syndrome.
- Call your doctor immediately if symptoms of kidney failure develop, including fatigue, nausea and vomiting, appetite loss, itching, headaches, impaired vision, or blood in the urine.
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Content excerpted from Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference.