Goodpasture's Syndrome is the Type of Glomerulonephritis Associated with PLAIR
Goodpasture's syndrome (anti-GBM disease) is the type of glomerulonephritis most commonly associated with Pulmonary-Renal Syndrome (PLAIR). 1
Understanding Pulmonary-Renal Syndrome (PLAIR)
Pulmonary-Renal Syndrome (PLAIR) is a clinical syndrome characterized by the combination of diffuse alveolar hemorrhage (DAH) and glomerulonephritis. This potentially life-threatening condition requires prompt diagnosis and treatment to prevent respiratory failure and end-stage renal disease.
Major Causes of PLAIR:
Goodpasture's Syndrome (Anti-GBM Disease):
- Accounts for approximately 20% of PLAIR cases 2
- Characterized by autoantibodies targeting type IV collagen in the glomerular and alveolar basement membranes 3
- Presents with necrotizing and crescentic glomerulonephritis on renal biopsy 4
- Often manifests as severe pulmonary hemorrhage and rapidly progressive glomerulonephritis
ANCA-Associated Vasculitis:
- Most common cause of PLAIR overall
- Includes granulomatosis with polyangiitis (formerly Wegener's) and microscopic polyangiitis
- Associated with anti-proteinase 3 (PR3-ANCA) or anti-myeloperoxidase (MPO-ANCA) antibodies 3
Other Less Common Causes:
- Systemic lupus erythematosus
- Cryoglobulinemia
- Antiphospholipid syndrome
Distinguishing Features of Goodpasture's Syndrome
Goodpasture's syndrome is distinguished from other causes of PLAIR by:
- Presence of anti-GBM antibodies targeting the alpha-3 chain of type IV collagen 5
- Linear IgG deposition along the glomerular basement membrane on immunofluorescence
- Necrotizing and crescentic glomerulonephritis pattern on renal biopsy 4
- Typically more fulminant pulmonary hemorrhage compared to other causes
Clinical Presentation and Diagnosis
The diagnosis of Goodpasture's syndrome in the context of PLAIR involves:
Clinical Presentation:
- Hemoptysis and respiratory distress
- Hematuria and proteinuria
- Rapidly declining renal function
Laboratory Testing:
- Positive anti-GBM antibodies in serum
- Negative or occasionally positive ANCA (dual-positive cases exist)
- Elevated serum creatinine
- Urinalysis showing hematuria and proteinuria
Pathologic Confirmation:
- Renal biopsy showing necrotizing and crescentic glomerulonephritis
- Linear IgG deposition along the glomerular basement membrane on immunofluorescence
- Lung biopsy (if performed) showing alveolar hemorrhage with linear IgG deposition
Treatment Approach
Treatment of Goodpasture's syndrome causing PLAIR requires aggressive intervention:
- Plasma exchange (plasmapheresis) to rapidly remove circulating anti-GBM antibodies
- High-dose corticosteroids (typically IV methylprednisolone followed by oral prednisone)
- Cyclophosphamide for immunosuppression
- Supportive care including mechanical ventilation and renal replacement therapy as needed 6
Prognosis
The prognosis for Goodpasture's syndrome has improved significantly with modern treatment:
- Early diagnosis and treatment are critical for preserving renal function
- Degree of renal impairment at presentation is the strongest predictor of outcome 5
- Percentage of crescents on renal biopsy correlates with prognosis
- Renal transplantation can be safely performed after disease activity has resolved 5
Common Pitfalls to Avoid
- Delayed diagnosis - Anti-GBM disease can progress rapidly; immediate testing for anti-GBM antibodies is essential when PLAIR is suspected
- Confusing with ANCA vasculitis - Some patients (10-40%) have both anti-GBM and ANCA antibodies ("double-positive"), requiring careful interpretation
- Inadequate immunosuppression - Treatment must be aggressive to prevent permanent organ damage
- Infection risk - Sepsis is a major contributor to mortality; antimicrobial prophylaxis should be considered 6
In conclusion, when evaluating a patient with PLAIR (pulmonary-renal syndrome), Goodpasture's syndrome should be high on the differential diagnosis, alongside ANCA-associated vasculitis, as these represent the most common etiologies.