From the Guidelines
Membranous nephropathy typically does not present with significant hematuria, and when hematuria is present, it is usually microscopic and mild. The classic presentation of membranous nephropathy is nephrotic syndrome, characterized by heavy proteinuria (>3.5g/day), hypoalbuminemia, edema, and hyperlipidemia 1. While microscopic hematuria may be present in about 30-50% of patients with membranous nephropathy, it is usually not a prominent feature of the disease. Gross hematuria is rare in membranous nephropathy and should prompt consideration of other diagnoses or complications, such as concurrent thin basement membrane disease, anticoagulant use, or other glomerular pathologies 1.
Key Points to Consider
- The pathophysiology of membranous nephropathy involves the formation of immune complexes that deposit on the subepithelial side of the glomerular basement membrane, causing damage to the podocytes and resulting in protein leakage 1.
- Membranous nephropathy is more common in men, with a male-to-female ratio of 2-3:1, and typically presents between the ages of 40 and 60 1.
- The presence of significant hematuria in a patient with suspected membranous nephropathy should prompt a thorough evaluation to rule out other diagnoses or complications, including malignancy, especially in patients with risk factors such as smoking, occupational exposure to chemicals, or a history of urologic disease 1.
- The KDIGO 2021 guideline for the management of glomerular diseases recommends a kidney biopsy to confirm the diagnosis of membranous nephropathy, especially in patients with atypical presentations or those who do not respond to treatment 1.
Clinical Implications
- Clinicians should be aware of the typical presentation of membranous nephropathy and consider alternative or additional diagnoses in patients with significant hematuria.
- A thorough evaluation, including a kidney biopsy, should be performed to confirm the diagnosis and rule out other complications.
- Patients with membranous nephropathy should be evaluated for associated conditions, such as malignancy, infections, or lupus, and treated accordingly 1.
From the Research
Presentation of Membranous Nephropathy
- Membranous nephropathy (MN) is a major cause of nephrotic syndrome in adults 2
- The etiology of approximately 75% of MN cases is idiopathic, while secondary causes include autoimmune diseases, infection, drugs, and malignancy 2
- The pathogenesis of MN involves the formation of immune complexes in subepithelial sites, leading to glomerular damage 2
Clinical Features
- Hematuria is not typically a primary presenting feature of membranous nephropathy, as the disease is more commonly associated with nephrotic syndrome 2, 3, 4, 5, 6
- Proteinuria is a hallmark of the disease, with patients often presenting with significant protein loss in the urine 2, 3, 4, 5, 6
Treatment and Outcomes
- Treatment options for MN include immunosuppressive agents, such as rituximab and cyclosporine, which have been shown to be effective in reducing proteinuria and inducing remission 3, 4, 6
- The choice of treatment depends on the severity of the disease and the presence of complications, such as renal insufficiency 5
- Studies have compared the efficacy of different treatment regimens, including rituximab and cyclosporine, with varying results 3, 4, 6