Membranous glomerulonephritis (MGN) is a slowly progressive disease of the kidney affecting mostly people between ages of 30 and 50 years, usually white people (i.e., those of European, Middle Eastern, or North African ancestry.). It is the second most common cause of nephrotic syndrome in adults, with focal segmental glomerulosclerosis (FSGS) recently becoming the most common. Signs and symptoms
Most people will present as nephrotic syndrome, with the triad of albuminuria, edema and low serum albumin (with or without kidney failure). High blood pressure and high cholesterol are often also present. Others may not have symptoms and may be picked up on screening, with urinalysis finding high amounts of protein loss in the urine. A definitive diagnosis of membranous nephropathy requires a kidney biopsy, though given the very high specificity of anti-PLA2R antibody positivity this can sometimes be avoided in patients with nephrotic syndrome and preserved kidney function

Causes
Primary/idiopathic
85% of MGN cases are classified as primary membranous glomerulonephritis—that is to say, the cause of the disease is idiopathic (of unknown origin or cause). This can also be referred to as idiopathic membranous nephropathy.One study has identified antibodies to an M-type phospholipase A2 receptor in 70% (26 of 37) cases evaluated.
Treatment
Treatment of secondary membranous nephropathy is guided by the treatment of the original disease. For treatment of idiopathic membranous nephropathy, the treatment options include immunosuppressive drugs and non-specific anti-proteinuric measures such as ACE inhibitors or angiotensin II receptor blockers. Given spontaneous remission is common, international guidelines recommend a period of watchful waiting before considering immunosuppressive treatment. Likelihood of achieving spontaneous remission is much higher if anti-proteinuric therapy with ace inhibitors or angiotensin II receptor blockers is commenced.Recommended first line immunosuppressive therapy often includes: cyclophosphamide alternating with a corticosteroid, also known as the Ponticelli regime. Immunosuppressive therapy options
Corticosteroids: They have been tried with mixed results, with one study showing prevention of progression to kidney failure without improvement in proteinuria. Chlorambucil
Cyclosporine
Tacrolimus
Cyclophosphamide
Mycophenolate mofetil
RituximabPerhaps the most difficult aspect of membranous glomerulonephritis is deciding which people to treat with immunosuppressive therapy as opposed to simple "background" or anti-proteinuric therapies. A large part of this difficulty is due to a lack of ability to predict which people will progress to end-stage kidney disease, or kidney disease severe enough to require dialysis. Because the above medications carry risk, treatment should not be initiated without careful consideration as to risk/benefit profile. Of note, corticosteroids (typically Prednisone) alone are of little benefit. They should be combined with one of the other 5 medications, each of which, along with prednisone, has shown some benefit in slowing down progression of membranous nephropathy.