Membranous nephropathy (MN) is an autoimmune disease. This means that the immune system starts to attack the kidneys. People with MN make antibodies that build up and cause damage to the kidneys. If this process happens on its own, it is called primary MN. If there are other causes, it is called secondary MN. Other causes could include a virus like hepatitis B or an autoimmune disease like lupus. Some medicines and even some types of cancer can also cause MN.


Protein loss in the urine will cause bubbles in the urine. Low protein levels in the blood can cause swelling of the legs, trouble breathing, and high blood pressure. You may also have high blood cholesterol levels and higher risk of blood clots and infections. It can also cause kidney failure.

How MN Is Diagnosed

MN is diagnosed by kidney biopsy. This biopsy removes a small piece of the kidney. The sample is looked at to check for antibodies that attack the kidneys. If you are found to have MN, you will need other tests to look for causes.


To treat MN, we need to figure out which type of MN you have. If it is secondary MN, then you will need treatment for the cause of MN. If you have primary MN, you will need medicine to stop your immune system from attacking your kidneys. Other treatments for both types of MN include:

  • Good blood pressure control with medicines that lower protein in urine.

  • Low salt diet.

  • Medicines to lower cholesterol.

  • High protein diet.

  • Diuretics (water pills) to help with swelling.

To Find Out More

The National Institute of Diabetes and Digestive and Kidney Diseases Health Information Center