Membranous Nephropathy is an immune-mediated glomerular disease characterized by thickening of the glomerular basement membrane, leading to heavy protein loss in the urine and development of nephrotic syndrome. It is one of the most common causes of nephrotic syndrome in adults and represents an important contributor to chronic kidney disease in nephrology practice.

The condition develops when antibodies target antigens located on the glomerular basement membrane, forming immune complexes that activate complement pathways and damage the filtration barrier. This immune-mediated injury allows large quantities of protein to leak into the urine, disrupting normal fluid balance and metabolic function. Membranous nephropathy may occur as a primary condition or secondary to infections, autoimmune diseases, medications, or malignancy.

Patients typically present with swelling of the legs, face, or abdomen, frothy urine, weight gain, and fatigue. Laboratory findings reveal significant proteinuria, low serum albumin levels, and elevated cholesterol. Kidney function may remain preserved initially but often declines gradually in untreated or high-risk cases.
Diagnosis is confirmed through kidney biopsy, which demonstrates characteristic thickening of the basement membrane and immune complex deposition. Blood tests help evaluate kidney function and identify possible secondary causes.

Management is guided by disease severity and risk of progression. Supportive care includes blood pressure control, reduction of proteinuria, management of edema, and prevention of complications such as thrombosis and infection. Immunosuppressive therapy may be indicated in patients with persistent nephrotic syndrome or declining kidney function. Close follow-up is required to monitor response and adjust treatment.
The course of membranous nephropathy is variable. Some patients experience spontaneous remission, while others progress to chronic kidney disease. Early risk assessment, individualized treatment, and long-term nephrology care are essential for optimal outcomes.