Membranous Nephropathy

Membranous nephropathy is a chronic autoimmune kidney disease that causes damage to the glomeruli, the tiny blood vessels in the kidneys that filter waste and excess fluid. This damage leads to protein leaking into the urine (proteinuria), a condition known as nephrotic syndrome. The disease can be primary (caused by the immune system attacking the kidney directly) or secondary (triggered by infections, cancer, medications, or other autoimmune conditions).

Swelling (edema) in the legs, ankles, feet, or around the eyes; Foamy urine (from protein loss); Weight gain from fluid retention; Fatigue; High blood pressure; Increased cholesterol levels; Frequent urination especially at night; In advanced stages, kidney failure.

Primary membranous nephropathy: Autoimmune response where the body creates autoantibodies (commonly against the PLA2R protein) on kidney cells. Secondary membranous nephropathy: Infections (e.g., hepatitis B, hepatitis C, syphilis), Certain medications (e.g., NSAIDs, gold therapy, penicillamine), Autoimmune diseases (e.g., lupus), Cancer (e.g., lung, colon, or breast cancer).

Urine tests to detect protein and assess kidney function; Blood tests for kidney function, autoantibodies (e.g., anti-PLA2R); Kidney biopsy to confirm the diagnosis and severity; Imaging to rule out secondary causes.

Supportive care: Blood pressure control (ACE inhibitors or ARBs), Diuretics for swelling, Statins for cholesterol, Anticoagulants (if high clot risk). Immunosuppressive therapy: Corticosteroids, Cyclophosphamide, Rituximab (a biologic used to reduce autoantibodies). Treatment is usually based on risk stratification.

Some people recover on their own (spontaneous remission). Others need long-term treatment and monitoring. Risk of kidney failure in 10-40% of patients over 5-10 years. Outcomes are improving thanks to newer treatments.

Roughly 10 per 100,000 people. Most common cause of nephrotic syndrome in adults. More common in men, typically diagnosed between ages 30 and 60.