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Atypical Renal Presentation in Diabetic — RACP Adult Medicine MCQ

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HardNephrologyAtypical Renal Presentation in DiabeticRACP Adult Medicine

A 55-year-old man with type 2 diabetes presents with sudden onset of nephrotic-range proteinuria (ACR 400 mg/mmol) and active urinary sediment (dysmorphic RBCs and RBC casts). eGFR has dropped from 75 to 35 over 6 weeks. He has NO diabetic retinopathy. ANA and anti-dsDNA are positive. C3 and C4 are low. What is the most appropriate next investigation?

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Correct answer: E — Renal biopsy

Rapid eGFR decline with active sediment (dysmorphic RBCs, RBC casts), nephrotic-range proteinuria, absence of diabetic retinopathy, and positive ANA/anti-dsDNA with low complement suggests lupus nephritis superimposed on (or instead of) diabetic nephropathy. Urgent kidney biopsy is indicated to classify the glomerulonephritis and guide treatment. Rapid GFR decline always warrants investigation.

Reference: KDIGO – 2021 – Glomerular Disease; EULAR 2024 Lupus Nephritis