Adult Urea Cycle Disorder — RACP Adult Medicine MCQ

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HardGeneral Internal MedicineAdult Urea Cycle DisorderRACP Adult Medicine

A 55-year-old man with hyperammonaemia and confusion but NORMAL liver function tests. What alternative cause?

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Correct answer: C — Urea cycle disorder (adult-onset)

Late-onset urea cycle disorders (OTC deficiency, X-linked) present with episodic hyperammonaemic encephalopathy. Normal LFTs distinguish from hepatic encephalopathy.

Reference: eTG – 2025; AMH – 2025