Membranous Nephropathy (MN)

Membranous nephropathy affects the glomerular filtering membrane, the layer inside the kidney's filters that normally keeps protein in the blood. In most cases the immune system is thought to produce antibodies, most often against a podocyte protein called PLA2R and less commonly against THSD7A, and these antibodies form immune deposits on the outer surface of the filtering membrane. Over time the membrane thickens and the filter's structure changes in a way that lets protein leak into the urine.

Membranous nephropathy is described as one of the most common causes of nephrotic syndrome in adults, and it can appear at any age. In roughly a third of cases the condition improves on its own with conservative management, and in another third it is understood to carry a higher risk of progressing toward reduced kidney function over the following decade, which is why ongoing monitoring matters.

Common signs

Foamy urine from heavy protein loss, swelling in the legs, ankles, or around the eyes, weight gain from fluid, and tiredness. Some people have few symptoms at first.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.