Makindo Medical Notes

Related Subjects: |Granulomatosis with Polyangiitis GPA (Wegener's) |Goodpasture's syndrome (Anti GBM disease) |Respiratory Failure |Acute Kidney Injury |Haemodialysis |

The prognosis of Goodpasture’s syndrome is highly dependent on the speed of treatment initiation. Many laboratories can perform rapid testing for ANCA and Anti-GBM antibodies. Early suspicion should prompt immediate consultation with a renal unit for timely intervention.

About

• Goodpasture's Syndrome (Anti-GBM Disease): A rare autoimmune disorder characterized by rapidly progressive glomerulonephritis (GN) and lung involvement.
• Occurs in approximately 1 case per million people per year.
• Leads to diffuse proliferative GN with crescent formation, causing rapid kidney damage.
• The inflammatory response results in collagen damage within the kidneys and lungs.

Classification

• Goodpasture’s Syndrome: Affects both the kidneys and lungs.
• Anti-GBM Disease: When the disease is limited to either the kidneys or lungs.

Aetiology

• Caused by the production of autoantibodies against the alpha-3 chain of Type IV collagen.
• This collagen is primarily found in the glomerular basement membrane (GBM) of the kidneys and alveolar basement membrane of the lungs.

Clinical Features

• Pulmonary: Lung haemorrhage, presenting with symptoms such as dyspnoea (shortness of breath) and haemoptysis (coughing up blood).
• Renal: Haematuria, proteinuria, and signs of acute kidney injury.
• Nephritic Syndrome: Occasionally presents with nephritic syndrome or rapidly progressive glomerulonephritis (RPGN).
• Progressive renal failure typically develops over the course of a few weeks if untreated.

Investigations

• Full Blood Count (FBC): Elevated white cell count (WCC), anaemia, and raised ESR/CRP, indicating inflammation.
• Urea & Electrolytes (U&E): Acute kidney injury pattern with raised urea and creatinine levels.
• Urinalysis: Proteinuria, haematuria, and red cell casts on urine microscopy.
• Chest X-ray (CXR): Shows alveolar shadowing, indicative of pulmonary haemorrhage.
• Serological Tests: Check for Anti-GBM antibodies and ANCA.
• Renal Biopsy: Confirms Anti-GBM nephritis. Immunofluorescence typically shows linear, ribbon-like deposition of IgG along the GBM, with diffuse crescentic glomerulonephritis.

Differential Diagnosis

• Granulomatosis with Polyangiitis (formerly Wegener's Granulomatosis): Must be distinguished from Goodpasture’s due to the presence of ANCA positivity and different histological features.

Management (Urgent Early Renal Consultation)

• Immunosuppression: Initiate high-dose steroids (e.g., Prednisolone 1 mg/kg) and cyclophosphamide to reduce inflammation and autoantibody production.
• Plasma Exchange (Plasmapheresis): Urgent plasmapheresis to remove circulating Anti-GBM antibodies.
• Renal Transplantation: Considered in end-stage renal disease. Recurrence in the transplant kidney is possible but rare; Anti-GBM antibody levels need to be reduced pre-transplant to prevent recurrence.