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Acute Intermittent Porphyria — RACP Adult Medicine MCQ

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ModerateGastroenterologyAcute Intermittent PorphyriaRACP Adult Medicine

A 25-year-old woman presents with recurrent episodes of severe abdominal pain, vomiting, and confusion. She is tachycardic and hypertensive. Urine turns dark red-brown on standing. Urine porphobilinogen (PBG) is markedly elevated. She was recently started on the combined oral contraceptive pill. What is the most likely diagnosis?

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Correct answer: B — Acute intermittent porphyria

Recurrent severe abdominal pain with neuropsychiatric features, tachycardia, hypertension, dark urine on standing, and markedly elevated urinary PBG triggered by OCP (oestrogen is a porphyrinogenic drug) is acute intermittent porphyria. Treatment of acute attacks: IV haem arginate (Normosang) + high carbohydrate intake + ceasing precipitant drugs. Givosiran (RNAi targeting ALAS1) is now available for prophylaxis.

Reference: eTG – 2024 – Porphyria; BPG 2024