Membranous nephropathy is a kidney disorder which involves changes and inflammation of the structures inside the kidney that help filter waste and fluids. The inflammation leads to problems with kidney function.

Membranous nephropathy is caused by thickening of part of the glomerular basement membrane. Glomerular basement membrane is a part of the kidneys that helps filter waste and extra fluid from the blood. The exact reason for this thickening is not known.

It is one of the most common causes of nephrotic syndrome. The condition may be a primary kidney disease of uncertain origin, or it may be associated with other conditions.

The following increase your risk for this condition:

• Exposure to substances or medications, including gold, mercury, penicillamine, trimethadione, and skin-lightening creams
• Hepatitis B
• Malaria
• Non-Hodgkin's lymphoma
• Solid cancerous tumors
• Systemic lupus erythematosus
• Syphilis

The disorder occurs in approximately 2 out of 10,000 people. It may occur at any age but is more common after age 40.

• Edema (swelling) in any area of the body
• Foamy appearance of urine
• Weight gain
• Poor appetite
• Urination, excessive at night
• High blood pressure

Note: Symptoms vary and in many cases there are no symptoms at all.

A physical exam may show swelling (edema).

A urinalysis may reveal protein in the urine or blood in the urine. Glomerular filtration rate (the "speed" of blood purification) is usually nearly normal.

Serum albumin may be low. Blood lipid levels may increase.

Kidney biopsy confirms the diagnosis of membranous nephropathy.

The goal of treatment is to reduce symptoms and slow the progression of the disease.

Symptoms should be treated as appropriate. Medications vary and may include corticosteroids, immunosuppressive drugs, blood pressure medications, and antibiotics (to control infections).

High blood cholesterol and triglyceride levels should be treated to reduce the risk of atherosclerosis secondary to nephrotic syndrome. A low-fat, low-cholesterol diet may be of limited benefit as the high levels of cholesterol and triglyceride seem to be caused by overproduction by the liver rather than eating too much fat. Medications to reduce cholesterol and triglycerides may be recommended.

The value of a high-protein diets has been debated. In many patients, reducing the amount of protein in the diet produces decrease in protein in the urine. In most cases, a moderate-protein diet (1 gram of protein per kilogram of body weight per day) is usually recommended.

Restricting salt may be help control edema. Vitamin D may need to be replaced if nephrotic syndrome is chronic and does not respond to therapy.

This disease increases the risk for blood clots in the lungs and legs.Patients are occasionally prescribed blood thinners to prevent these complications.

The outlook varies. There may be symptom-free periods and acute flare ups. In some cases, the condition may go away with or without therapy.

The majority of patients will have some degree of irreversible kidney damage within 2-20 years. About 20% of those will progress to end-stage renal disease.

• Nephrotic syndrome
• Chronic renal failure
• End-stage renal disease
• Renal vein thrombosis
• Pulmonary embolism

Call for an appointment with your health care provider if symptoms indicate membranous nephropathy may be present. Call for an appointment with your health care provider if symptoms worsen or persist, if you experience a decreased urine output or other new symptom develops.

Promptly treating associated disorders and avoiding associated substances may reduce risk.