Introduction
Glomerulonephritis (GN) is inflammation of the glomeruli, usually immune-mediated. It presents in two main patterns: the nephritic syndrome (inflamed, leaky to blood) and the nephrotic syndrome (leaky to protein). Many diseases mix both. In children, the commonest acute GN is post-streptococcal, and the commonest nephrotic syndrome is minimal change disease.
Acute post-streptococcal glomerulonephritis (APSGN)
Immune complexes after infection with a nephritogenic group A streptococcus: 1–2 weeks after a throat infection or 3–6 weeks after a skin infection (impetigo). Mostly 5–12 years.
- Cola- or tea-coloured urine, puffy eyes, reduced urine, hypertension (headache, sometimes encephalopathy with seizures), fluid overload (breathlessness, heart failure).
- Tests: urine (red cells, casts, protein), creatinine, electrolytes; evidence of strep (ASO, anti-DNase B, culture); low C3 with normal C4.
- C3 returns to normal within 6–8 weeks. If it stays low, or kidney function worsens, think of another disease (C3 glomerulopathy, membranoproliferative GN, lupus) and biopsy.
- Treatment is supportive: fluid and salt restriction, diuretics (furosemide) for overload, antihypertensives; penicillin to clear the strain; dialysis rarely.
- Outlook is excellent: urine output and blood pressure recover in 1–2 weeks; microscopic haematuria can last 1–2 years.