Rapidly Progressive Glomerulonephritis (RPGN)

Related Subjects: |Metabolic acidosis |Lactic acidosis |Acute Kidney Injury (AKI) / Acute Renal Failure |Renal/Kidney Physiology |Chronic Kidney Disease (CKD) |Anaemia in Chronic Kidney Disease |Analgesic Nephropathy |Medullary Sponge kidney |IgA Nephropathy (Berger's disease) |HIV associated nephropathy (HIVAN) |Balkan endemic nephropathy (BEN) |Autosomal Dominant Polycystic kidney disease

⚠️ Key Point: Rapidly Progressive Glomerulonephritis (RPGN) is a renal emergency. Untreated, it can destroy kidneys within weeks. Early nephrology referral and aggressive therapy can be life-saving.

About 🧾

• 🚑 RPGN = rapid decline in kidney function over days to weeks.
• 🧪 Histology: necrotising glomerulonephritis with crescents (crescentic GN).
• 🔑 Key tests: Anti-GBM antibodies, ANCA (pANCA, cANCA).
• 🧬 Can be primary (idiopathic) or secondary to systemic disease.

Types of RPGN 🧩

• Type I – Anti-GBM disease: Linear immune deposits (Goodpasture’s syndrome).
• Type II – Immune complex: Granular immune staining (SLE, post-strep GN, IgA nephropathy, cryoglobulinemia).
• Type III – Pauci-immune: No staining; usually ANCA-associated vasculitis (GPA, MPA, EGPA).

Clinical Features 👩‍⚕️

• 🩸 Haematuria ± proteinuria.
• 💧 Oedema + hypertension.
• 😴 Symptoms of uraemia: fatigue, nausea, confusion.
• ❤️ Pericarditis: pericardial rub may be heard.
• 🩹 Skin: purpura, petechiae in vasculitis.
• 🫁 In Goodpasture’s: haemoptysis from alveolar haemorrhage.

Investigations 🔍

• 🧪 Urinalysis: blood, protein, red cell casts (classic).
• 🧬 Serology:
  • Anti-GBM → Goodpasture’s
  • cANCA (PR3) → GPA
  • pANCA (MPO) → Microscopic polyangiitis
  • ANA/dsDNA → SLE
• 📉 Complement: low in SLE, post-strep, cryoglobulinemia.
• 🩻 CXR: alveolar infiltrates in pulmonary haemorrhage.
• 🔬 Renal biopsy: shows crescents + necrosis (gold standard).

Management 🩺

• 💊 Immunosuppression: high-dose corticosteroids + cyclophosphamide (or rituximab in some ANCA vasculitis).
• 💉 Pulsed IV methylprednisolone for severe cases.
• 🩸 Plasma exchange: indicated in Goodpasture’s and severe ANCA vasculitis with pulmonary haemorrhage.
• 💧 Supportive: fluids, dialysis if renal failure, BP control.

Prognosis 📈

• 🚨 Without treatment → most progress to ESRF within weeks.
• ✅ With prompt therapy: renal survival depends on early diagnosis + degree of crescent formation at biopsy.

Exam Pearl ✨: Think RPGN in a patient with rapidly rising creatinine, haematuria, and systemic features. Always check ANCA + Anti-GBM early to guide urgent therapy.

Cases — Rapidly Progressive Glomerulonephritis (RPGN)

• Case 1 — Post-infectious immune complex (Type II) 🦠: A 19-year-old man presents with malaise, haematuria, and reduced urine output 3 weeks after a sore throat. BP 160/95, oedema present. Urine: red cell casts, proteinuria. Renal biopsy: crescentic GN with immune complex deposition. Diagnosis: post-infectious RPGN. Managed with supportive care, BP control, and nephrology input.
• Case 2 — Goodpasture’s syndrome (Type I) 🫁🩸: A 32-year-old man presents with haemoptysis, dyspnoea, and rapidly progressive renal failure. Urine: microscopic haematuria, mild proteinuria. Bloods: anti-GBM antibodies positive. Renal biopsy: linear IgG deposition. Diagnosis: Goodpasture’s disease with RPGN. Managed with plasma exchange, steroids, and cyclophosphamide.
• Case 3 — ANCA-associated vasculitis (Type III) 🌐: A 55-year-old woman presents with fatigue, haematuria, purpuric rash on legs, and sinusitis. Bloods: creatinine rising, ANCA positive. Renal biopsy: pauci-immune crescentic GN. Diagnosis: RPGN secondary to microscopic polyangiitis. Managed with high-dose steroids, cyclophosphamide, and later rituximab.

Teaching Point 🩺: RPGN is a clinical syndrome of rapidly declining renal function with crescentic GN on biopsy. Causes include anti-GBM disease, immune complex GN, and ANCA-associated vasculitis. Early recognition and urgent immunosuppression are vital to preserve renal function.