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

💡 Key Point: Early Penicillin therapy of streptococcal infection does not prevent the development of acute post-streptococcal glomerulonephritis (PSGN).

About 🧾

• 👶 A common cause of acute glomerulonephritis in children and young adults.
• 🗓️ Occurs 1–2 weeks after streptococcal pharyngitis, or 3–6 weeks after streptococcal skin infection.
• 🔬 Pathology: immune complex–mediated damage to glomeruli → inflammation + reduced filtration.

Aetiology 🦠

• Most often caused by Group A β-haemolytic Streptococcus.
• Immune reaction is delayed (10–14 days post-infection).
• Other triggers: staphylococcal infections (skin, endocarditis, pneumonia).

Clinical Features 👩‍⚕️

• 🩸 Haematuria: “Smoky” or “tea-coloured” urine (classic sign).
• 😴 Oliguria – reduced urine output, fluid overload.
• 💧 Oedema: periorbital puffiness, ankle swelling.
• 💢 Hypertension: common and sometimes severe.

Investigations 🔍

• Urine dip: blood + proteinuria (< 3 g/day).
• 🧪 ASO titres: elevated in 95% with recent throat infection.
• Low complement (C3 ± C4), usually recovers in 6–8 weeks.
• U&E: may show ↑ urea & creatinine.
• Renal biopsy (if atypical): shows IgG + C3 immune deposits (“starry sky” appearance).

Management 🩺

• 🌊 Supportive care: fluid and salt restriction.
• 💊 Diuretics: for oedema and hypertension.
• 🧘 Blood pressure control: antihypertensives if needed.
• 🦠 Antibiotics: treat active infection, but do not alter PSGN course.
• 🚑 Rare: rapidly progressive GN may occur → consider immunosuppressants + dialysis.

Prognosis 📈

• 👍 Most children make a full recovery.
• ⏳ A small proportion may develop long-term sequelae: CKD or persistent proteinuria decades later.

Exam Pearl ✨: Think PSGN when you see a child with smoky urine + periorbital oedema + hypertension following a sore throat or skin infection.

Cases — Post-Streptococcal / Infectious Glomerulonephritis

• Case 1 — Classic child presentation 👦: A 7-year-old boy presents with dark “cola-coloured” urine, periorbital oedema, and mild hypertension, 2 weeks after a sore throat. Urine: red cell casts, proteinuria. Bloods: low C3 complement, raised anti-streptolysin O titre. Diagnosis: post-streptococcal glomerulonephritis. Managed supportively with salt restriction, diuretics, and BP control.
• Case 2 — Skin infection trigger 🩹: A 10-year-old girl develops oedema and haematuria following impetigo treated 3 weeks earlier. Urine microscopy: dysmorphic red cells. BP 150/90. Diagnosis: post-infectious GN following streptococcal skin infection. Managed with fluid balance monitoring, diuretics, and antibiotics if infection persists.
• Case 3 — Adult infection-related GN 🧍‍♂️: A 45-year-old man with type 2 diabetes is hospitalised with infective endocarditis. He develops haematuria, proteinuria, and worsening renal function. Complement levels low. Diagnosis: infection-associated immune complex GN. Managed with IV antibiotics for endocarditis, BP control, and nephrology support.

Teaching Point 🩺: Post-streptococcal / infectious GN typically follows throat or skin streptococcal infection after a 1–3 week latent period. Presents with the nephritic syndrome: haematuria, hypertension, oedema, and renal impairment. Most children recover fully; adults have higher risk of CKD.