skip to main content

Primary Hyperoxaluria Type 1 — RACP Adult Medicine MCQ

Instant feedback + full explanation. One question, done properly.

HardNephrologyPrimary Hyperoxaluria Type 1RACP Adult Medicine

A 20-year-old man with a strong family history of kidney stones presents with bilateral renal calculi. 24-hour urine shows massively elevated oxalate (>1000 μmol/day). He has normal bowel function. Plasma oxalate is elevated. Genetic testing reveals AGXT gene mutation. eGFR is 55 mL/min/1.73m². What is the most likely cause?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Primary hyperoxaluria

Massively elevated urine and plasma oxalate with AGXT mutation is primary hyperoxaluria type 1 (PH1) — an autosomal recessive disorder causing hepatic overproduction of oxalate. It causes nephrocalcinosis, CKD, and systemic oxalosis. Lumasiran (RNA interference therapy targeting HAO1) reduces oxalate production and is now approved. Pyridoxine (B6) is first-line for B6-responsive PH1 (30-50% of cases). Liver-kidney transplant for ESKD.

Reference: KDIGO – 2024; ERA PH1 Guidelines 2024