Chronic kidney disease (CKD) has several potential causes, including genetics and environmental factors. In the case of membranous nephropathy (MN), it most commonly develops from an autoimmune reaction. Learn more about what membranous nephropathy is, including its symptoms, other causes, how it’s diagnosed, available treatments, and how this type of kidney disease progresses.*

What is membranous nephropathy? 

Membranous nephropathy occurs when the body’s immune system attacks the glomeruli (tiny filtering units inside the kidney) and affects how your kidney cleans waste products out of the blood. This can happen either suddenly or gradually over time. 

The damaged glomeruli can cause protein to leak out into the urine; the presence of protein in your urine is called proteinuria. For some people, losing protein can lead to nephrotic syndrome and/or kidney failure.  

What causes MN?

There are two types of MN, idiopathy (primary) and secondary), and the type you have is defined by what caused it. Idiopathic, or primary, MN is the most common and is caused by an autoimmune response. According to the Cleveland Clinic, “Most cases of MN are now known to be caused by an antibody to a protein on the podocyte called the phospholipase A2 receptor (PLA2R).” This antibody attacks the protein instead of the infection, which causes proteinuria and, subsequently, primary MN.

Other potential causes of MN, or secondary MN, are typically caused by another disease or drug and include the following: 

• Hepatitis B virus (HBV)
• Non-steroidal anti-inflammatory drugs (NSAIDs)
• Systemic lupus erythematosus (also known as Lupus)
• Cancer
• Parasitic diseases, like malaria
• Other diseases and infections

What are the signs and symptoms to look out for? 

For people whose MN develops gradually, they may experience little to no symptoms. As protein loss increases, however, signs and symptoms typically become more noticeable. 

The potential signs and symptoms are:

• Swelling (edema) in the legs and ankles
• Weight gain
• Fatigue
• Poor appetite
• Foamy urine
• High cholesterol
• Increased protein in the urine (proteinuria)
• Decreased protein in the blood, particularly albumin
• Increased blood pressure

How is membranous nephropathy diagnosed?

There are a couple of common tests your doctor will run to diagnose MN: 

• Urine tests to find protein and blood in the urine
• Blood tests to assess levels of protein, cholesterol, and wastes in the blood

Your glomerular filtration rate (GFR) will also be calculated from the results of the blood tests.  

What treatment options are available? 

Depending on the severity of MN, your doctor and healthcare providers will either monitor it closely without the use of medication or provide supportive treatment. 

Supportive treatment options may include: 

• Medications, such as ACE inhibitors or ARBs, may be prescribed to help reduce blood pressure and proteinuria.
• Diuretics may be used if you are experiencing swelling from fluid buildup. They will also help increase your urine output.
• A low-salt diet can help decrease fluid buildup in your body. 

Can MN lead to kidney failure?

 In some people, membranous nephropathy can cause your kidneys to gradually lose function, in which case dialysis or a kidney transplant will eventually be necessary. On the other hand, many people respond well to treatment and may live for many years without signs of change in their MN.

More information on membranous nephropathy can be found on the Mayo Clinic and National Kidney Foundation websites.

*Cleveland Clinic. (2019, Oct. 9). Membranous Nephropathy. https://my.clevelandclinic.org/health/diseases/21154-membranous-nephropathy