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APSGN C3 Recovery — RACP Paediatrics MCQ

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ModerateNephrologyAPSGN C3 RecoveryRACP Paediatrics

A 3-year-old presents with gross haematuria, hypertension, and oedema 10 days after pharyngitis. Complement C3 is very low. C4 is normal. Renal function is mildly impaired. After how many weeks should C3 normalise in APSGN?

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Correct answer: B — 6-8 weeks

In APSGN, C3 is characteristically low (via alternative complement pathway activation) and normalises within 6-8 weeks. If C3 remains low beyond 8-12 weeks, alternative diagnoses should be considered (MPGN, lupus nephritis, C3 glomerulopathy).

Reference: RCH Melbourne – 2024 – Clinical Practice Guidelines: Glomerulonephritis