Membranous Nephropathy

Exam Cram

• Commonest cause of nephrotic syndrome in adults

• Aetiology: idiopathic (primary) or secondary to, e.g. HBV or lung cancer

• Diagnosis: renal biopsy & investigate for secondary causes

• Idiopathic membranous nephropathy management: steroids + cyclophosphamide

Outline

Background 

• Commonest cause of nephrotic syndrome in adults

• Membranous nephropathy caused by a thickened glomerular basement membrane, observed on renal biopsy

Assessment

History:

• Weight gain, lethargy

• Insidious

Examination:

• Fluid overload

Investigations

• Creatinine rise

• Urinalysis: protein & raised 24hr protein collection

• Renal biopsy- diffuse thickening of glomerular basement membrane

Diagnosis

First diagnose nephrotic syndrome, then membranous nephropathy then its underlying cause. 

Diagnostic criteria

1. Nephrotic Syndrome: 4/4-proteinuria & hypoalbuminaemia, peripheral oedema, hyperlipidaemia

2. Membranous Nephropathy: renal biopsy changes

3. Core Causes:

   1. Idiopathic (rule out other causes)

   2. Secondary (chronic inflammation): 

• Infective: HBV, HCV, syphillis, Infective Endocarditis 

• Inflammatory: Systemic Lupus Erythematous ,

• Cancers: lung cancer, CRC, Cryoglobulinemia 

• Drugs: penicillamine, NSAIDs

• Toxins: gold, mercury

Management

Work Up 

1. Nephrotic Syndrome: 

   • Frusemide, anticoagulant, statins, ACEi

   • Low salt diet

   • Renal biopsy ?cause

2. Secondary causes

   • ANA +- anti-dsDNA

   • HBV, HCV, Syphillis

   • Complement levels

   • Cryoglobulin test

Idiopathic Membranous Nephropathy

• Prednisolone & Cyclophosphamide

• Rituximab

• MMF

Med Reg Notes

Cancer Induced Membranous Nephropathy

Rough %

• Lung Cancer 25%

• CRC 10%

• Prostate Cancer 15%

• Gastric/ Breast < 10%

Management

Conflicting info on prednisolone in membranous nephropathy, some prefer rituxumab as first line. 

References

1. Alok A, Yadav A. Membranous Nephropathy. [Updated 2023 Jun 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559169/

2. https://www.mountsinai.org/health-library/diseases-conditions/membranous-nephropathy

Page written in 2024.