The kidneys have filters that are responsible for cleaning waste products from your blood. In membranous nephropathy (MN), these filters are attacked by the body’s immune system. Grouped together, the symptoms of this disease are called nephrotic syndrome. Treatment for MN depends on the type and cause of the condition.
Membranous nephropathy (MN) is a disorder where the body’s immune system attacks the filtering membranes in the kidney. These membranes clean waste products from the blood.
Each kidney has thousands of tiny filtering units called glomeruli. These filtering units are made up of blood vessels so small, they only have three layers:
The glomerular basement membrane is so thin that it acts as a filter.
MN can develop very suddenly or slowly get worse over a long time. Some people do not know they have the condition for many years. It is also known as membranous glomerulonephritis.
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If inflammation (or anything else) damages any of these three layers, the kidneys cannot work correctly. When the podocyte layer is damaged, it can cause high levels of protein to leak from the kidneys into the urine.
People who have higher risk for MN include those who:
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). In most people with MN, the body’s immune (defense) system makes an antibody (a protein that normally helps fight infections). Instead of targeting an infection, these antibodies attack the podocytes. The podocytes stop retaining the proteins in the blood stream and allow them to leak into the urine. This is called primary MN. Less commonly, MN can be due to other causes (secondary MN), such as:
The main symptoms of MN are from the loss of protein into the urine because of the damaged podocyte cells. Together, the symptoms of MN are called nephrotic syndrome. Signs of nephrotic syndrome include:
Some people with MN do not notice any symptoms. In these individuals, doctors may find signs of MN during a regular office visit or when testing for another issue.
If you have any symptoms of nephrotic syndrome (protein in your urine with swelling or decreased kidney function), you should be referred to a nephrologist. A nephrologist is a doctor who specializes in diseases and conditions of the kidneys. Your nephrologist will use several tests to confirm an MN diagnosis. These tests can include:
Treatment for MN depends on the type and cause. If you have primary MN and the levels of protein in your urine are not severe, your kidney function is stable and you have not had a complication of MN (such as a blood clot), your nephrologist may choose to use the following treatments without medications to suppress your immune system for six to 12 months since some cases may resolve on their own.
These treatments may include:
However, if any of the previously mentioned factors are present or the proteinuria does not decline during the observation period, your nephrologist will likely use immunosuppressive therapy.
In some people with secondary MN, treating the underlying condition may stop kidney damage from progressing.
Health issues and complications from membranous nephropathy can include:
Additional complications that can happen due to MN can include:
Pulmonary embolism and renal vein thrombosis can be life-threatening complications that require emergency medical treatment. Symptoms of each condition can include:
If you experience these symptoms, call 911 or go to an emergency department.
For most cases of membranous nephropathy, there is not anything that can be done to prevent it since it is an autoimmune process. For those cases caused by other disease, treating and controlling those diseases may help reduce complications from them, such as MN.
The prognosis for MN varies depending on the person. In some cases, the disease goes away on its own without treatment. For others the disorder can continue for many years without getting worse.
MN can come back after treatment. Your nephrologist may monitor your kidney function regularly to look for signs that the disorder has returned. This monitoring will allow your doctor 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 occurring. This practice can vary by nephrologist and the patient.
You will not know that you have MN based on any symptoms since many different problems can cause them. Contact your healthcare provider if you notice unexplained swelling in your face, arms or legs.
If you have MN, you may want to ask your doctor:
Last reviewed by a Cleveland Clinic medical professional on 10/09/2019.
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