Makindo Medical Notes

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

Rapidly Progressive Glomerulonephritis (RPGN) is a serious cause of renal failure that, with early treatment, can help prevent irreversible kidney damage. It should be treated as a renal emergency, with early referral to nephrology to prevent permanent kidney destruction within weeks.

About

• Rapidly Progressive Glomerulonephritis (RPGN) is a medical emergency requiring urgent nephrology referral.
• Characterized by a rapid decline in kidney function over days to weeks.
• Early diagnosis and treatment can prevent severe renal damage.
• Key investigations include anti-GBM (glomerular basement membrane) and ANCA (anti-neutrophil cytoplasmic antibody) tests.
• Histological hallmark: focal necrotizing glomerulonephritis.

Types of RPGN

• Primary RPGN: Idiopathic (no known cause).
• Secondary RPGN: Associated with various underlying conditions, including:
• Goodpasture's syndrome (anti-GBM disease).
• Granulomatosis with polyangiitis (formerly Wegener's granulomatosis).
• Systemic lupus erythematosus (SLE) – typically presents with low complement levels.
• Henoch-Schönlein purpura (IgA vasculitis).
• IgA nephropathy.
• Post-streptococcal/Post-infectious glomerulonephritis (often with low complement levels).
• Cryoglobulinemia (low complement levels).

Differential Diagnosis of Rapidly Progressive Glomerulonephritis

Clinical Features

• Symptoms of uraemia (e.g., nausea, fatigue, confusion).
• Pericardial rub (indicative of pericarditis).
• Hypertension.
• Bruising, petechiae, or skin rash.
• Haematuria (blood in urine) – may not always be visible.

Investigations

• Urinalysis and Microscopy: Presence of blood, protein, and red cell casts.
• FBC (Full Blood Count): Anaemia, particularly if alveolar haemorrhage is present.
• Renal Function Tests: Raised creatinine and urea, indicating kidney damage.
• Inflammatory Markers: Elevated CRP and ESR, suggesting systemic vasculitis.
• Complement Levels: May be low in certain conditions (e.g., SLE, post-streptococcal GN).
• Specific Antibody Tests:
• cANCA (Proteinase-3): Granulomatosis with polyangiitis.
• pANCA: Microscopic polyangiitis.
• ANA, DsDNA: Systemic lupus erythematosus (SLE).
• Anti-GBM antibodies: Goodpasture's syndrome.
• Renal Ultrasound (USS): Typically shows normal kidney size, but biopsy is key for diagnosis.
• Renal Biopsy: Shows necrosis and crescent formation in the glomeruli.
• Chest X-ray (CXR): May show cavitating lung lesions or alveolar haemorrhage in Granulomatosis with polyangiitis.

Management

• Immunosuppressive Therapy: Steroids and cyclophosphamide are first-line treatments.
• Plasma Exchange: Used to remove circulating antibodies, especially in Goodpasture's syndrome or ANCA-associated vasculitis.
• Pulsed Methylprednisolone: Used for rapid immunosuppression in severe cases, though prognosis can still be poor.
• Prognosis: Without treatment, many patients progress to end-stage renal failure.