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Membranous Nephropathy (MN)

What is Membranous Nephropathy?

Membranous nephropathy (MN) is a kidney disease that is caused by an abnormal build up of immune proteins in the part of the kidney filter known as the glomerular “basement membrane”.  This part of the glomerulus is the thin bit of tissue that helps separate the blood from the urine.  In membranous nephropathy the basement membrane becomes thick and damaged, allowing large amounts of protein to leak out of the blood and into the urine.

Who gets Membranous Nephropathy?

Anyone can have Membranous Nephropathy but it is more common in adults over the age of 40.

What causes Membranous Nephropathy?

Often the underlying cause of membranous nephropathy is not known (idiopathic), but it can be associated with other conditions. It occasionally develops in people with some types of cancers, or as a result of a side effect of some drugs. Other immune diseases, like lupus, can also cause a membranous nephropathy. And some infections, such as hepatitis B and C, can also have kidney involvement with MN. 

What are some of the symptoms of Membranous Nephropathy?

Symptoms occur gradually and can include swelling, weight gain, and high blood pressure. .

How is Membranous Nephropathy diagnosed?

With information obtained from blood tests, urine tests and a kidney biopsy, a physician can determine if a patient has Membranous Nephropathy.

What is the treatment for Membranous Nephropathy?

Limiting salt in the diet and using medications to help the body get rid of extra salt and water is often helpful. Blood pressure medications such as ACE inhibitors are often used to try to decrease the loss of protein in the urine. Sometimes medicines are prescribed to decrease the chance of blood clots, which can be a problem in patients with nephrotic syndrome. For people with large amounts of protein in the urine, or who appear to be having long term damage to their kidneys, immunosuppression medications are frequently used. These include corticosteroids, cyclosporine, tacrolimus, and cyclophosphamide.

Frequently Asked Questions

What is the outlook for a patient with Membranous Nephropathy?

Interestingly, MN sometimes goes away on its own. During the first 5 years after onset, this may happen in 1/3 of cases, even without any particular treatment.  It is more likely if there is a mild or moderate amount of protein in the urine, and less likely if there is a large amount of protein in the urine.  Another 1/3 of people seem to have a very stable course over many years, with no worsening and no improvement. And the remaining 1/3 have a slow decline in kidney function or worsening in the amount of protein in the urine, with up to 40% progressing to kidney failure after 15 years.

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