Membranous Nephropathy

What is membranous nephropathy (MN)?

Membranous nephropathy (MN) is a condition that causes your immune system to attack glomeruli, the tiny filters in your kidney. Your kidneys have thousands of glomeruli. These filters clean waste products from your blood. If you have membranous nephropathy, your glomeruli become inflamed. MN can cause your kidneys to stop filtering waste as well as they should.

MN can develop suddenly or slowly get worse over a long time. It’s common for people to have MN for several years and not know it. MN is a type of glomerular disease. Other terms for MN are membranous glomerulopathy or membranous glomerulonephritis.

Types of membranous nephropathy

There are two types of membranous nephropathy:

• Primary membranous nephropathy (idiopathic): This is a condition that directly affects your kidneys. It’s usually due to an autoimmune condition. Up to 75% of people have this type.
• Secondary membranous nephropathy: This type happens when another health condition or treatment affects your kidneys. About 25% of people have this type.

How common is membranous nephropathy?

It’s rare. Only about 1 in every 5,000 people has this condition. It’s more common in men and people assigned male at birth (AMAB) aged 50 to 60. Children rarely get membranous nephropathy.

What are the symptoms of membranous nephropathy (MN)?

The main symptoms of MN are from excess protein in your pee due to kidney damage. This leads to water retention and other symptoms. Together, these symptoms are called nephrotic syndrome. Other than edema (swelling), other signs can include:

• Proteinuria (foamy-looking pee due to high levels of protein in your pee).
• High cholesterol.
• Peeing more or less than usual.
• Weight gain (people usually gain water weight because of the swelling).
• Fatigue (tiredness).
• High blood pressure.
• Trouble breathing or shortness of breath.

What’s the most common cause of membranous nephropathy (MN)?

Primary membranous nephropathy is an autoimmune disease, which means your body is attacking healthy cells in your body. If you have MN, your body’s immune system makes an antibody (a protein that normally helps fight infections) to a protein called the phospholipase A2 receptor (PLA2R). Instead of targeting an infection, these antibodies attack certain healthy cells in your kidney. Your kidney stops being able to filter the proteins in your bloodstream, which allows them to leak into your pee.

Having an underlying medical condition that damages your kidneys puts you at risk for secondary MN. Some examples of medical conditions include:

• Autoimmune conditions like lupus or rheumatoid arthritis.
• Infections like malaria, hepatitis B, hepatitis C or syphilis.
• Cancer (especially colon or lung).
• NSAIDs (nonsteroidal anti-inflammatory drugs) and other medications like penicillamine.
• Exposure to mercury or other toxins.

What complications can happen if I have membranous nephropathy (MN)?

Health issues and complications from membranous nephropathy can include:

• High cholesterol (higher than average levels of fat in your blood).
• High blood pressure.
• Severe swelling.
• Kidney disease.
• Kidney failure.
• Deep vein thrombosis (DVT).
• Pulmonary embolism (PE).

How is membranous nephropathy (MN) diagnosed?

If you have any symptoms of nephrotic syndrome (like protein in your pee, swelling or decreased kidney function), your primary care provider may refer you to a nephrologist. A nephrologist is a healthcare provider who specializes in diseases and conditions of the kidneys. Your nephrologist will use several tests to confirm an MN diagnosis. These tests can include:

• Blood test: Taking a sample of blood to measure kidney function. Specific tests include blood urea nitrogen (BUN), creatinine and albumin.
• Glomerular filtration rate (GFR): Studying a blood sample to see the speed at which your kidneys are filtering waste.
• Kidney biopsy: Taking a small sample of kidney tissue and sending it to a lab to see if it contains an antibody associated with MN.
• Urine test: Measuring levels of protein and blood in your urine.

Your healthcare provider may also order tests to diagnose what’s potentially causing secondary MN. These could include tests for certain infections, an antinuclear antibody test and an anti-double stranded DNA test.

What are the treatments for membranous nephropathy (MN)?

Treatment for MN depends on the type and your symptoms. The goal of treatment is to reduce your symptoms and stop the disease from getting worse. Your healthcare provider may try one or several treatments to help you.

These treatments may include:

• Angiotensin-converting enzyme (ACE) inhibitors: Drugs that manage high blood pressure, lower urine protein levels and help reduce inflammation in your kidneys.
• ARBs (angiotensin receptor blockers): Medication to treat high blood pressure and kidney disease.
• Diuretics: Medications that remove excess fluid from your body (by causing you to pee more) and lower blood pressure.
• Cholesterol-lowering medications (statins): Medication to reduce cholesterol levels.
• Corticosteroids: Medication to reduce inflammation and suppress your immune system (this helps it not attack your healthy cells).
• Blood thinners: Drugs that lower your risk for blood clots.
• Changes to your diet: Reducing salt intake and keeping your overall protein intake at a moderate level. Your healthcare provider will recommend what types of diet changes you should make.

If these treatments don’t help your symptoms, your healthcare provider may recommend immunotherapy. Immunotherapy drugs stop your immune system from producing the antibody that attacks your kidneys. Some examples of immune-suppressing medications include cyclophosphamide (Cytoxan®) and rituximab (Rituxan®).

If your kidneys show severe damage, your provider may recommend a kidney transplant.

In some people with secondary MN, treating the underlying health condition may stop kidney damage from progressing.

Is there a cure for membranous nephropathy?

No, there isn’t a cure for membranous nephropathy. There’s only treatment to manage your symptoms and stop the disease from progressing.

How can you prevent membranous nephropathy (MN)?

It’s hard to prevent primary membranous nephropathy because it’s an autoimmune process. But you may be able to reduce your chances of secondary membranous nephropathy by treating and managing diseases that could lead to it.

What is the outlook for people with membranous nephropathy (MN)?

The prognosis for MN varies depending on the person. In some cases, the disease goes away on its own with little to no treatment. For others, the disease can continue for many years.

Some people with MN end up with kidney failure. These people may need a kidney transplant or dialysis (treatment where a machine filters the blood for your kidneys).

MN can come back, even after treatment. Your nephrologist may monitor your kidney function regularly to look for signs of MN. This monitoring will allow your provider to treat you as soon as possible if MN recurs. Your nephrologist may also keep you on medication to suppress your immune system for longer periods of time to reduce the chances of a flare-up.

Is membranous nephropathy fatal?

It can be. If MN causes kidney damage that eventually leads to kidney failure, it can be life-threatening. It’s important to remember that kidney failure occurs in less than 15% of people with MN. This means that most people don’t experience kidney failure or need kidney dialysis.

When should I see a healthcare provider about membranous nephropathy (MN)?

Contact a healthcare provider if you notice unexplained swelling in your legs, feet or arms. This is often one of the first signs of MN.

If you’ve received a diagnosis of MN already, contact your healthcare provider if you notice any changes in your symptoms or overall health. They can adjust your treatment and find a way to help you feel better.