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IgAN Synpharyngitic Short Latent Period — ESENeph MCQ

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EasyGlomerulonephritisIgAN Synpharyngitic Short Latent PeriodESENeph

A 44-year-old man presents with acute loin pain and macroscopic haematuria 2 days after a viral upper respiratory tract infection. He had similar episodes previously. Urine dipstick: blood 3+, protein 2+. Creatinine is 110 umol/L. What feature of this presentation is MOST suggestive of IgA nephropathy rather than post-infectious glomerulonephritis?

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Correct answer: E — Short latent period between infection and symptoms

The key distinguishing feature is the SHORT latent period (1-2 days) between the URTI and onset of haematuria — so-called 'synpharyngitic' haematuria. In IgA nephropathy, haematuria occurs DURING or within 1-3 days of the mucosal infection (respiratory or GI). In contrast, post-streptococcal GN has a latent period of 1-3 weeks (pharyngitis) or 3-6 weeks (skin infection) — the time needed for immune complex formation. This temporal relationship is a classic clinical pearl for differentiating these two conditions. Both can cause macroscopic haematuria and proteinuria; both are more common in males.

Reference: KDIGO 2025 – IgAN/IgAV Guideline; JRCPTB 2022 – Nephrology Curriculum