Acute Intermittent Porphyria — RACP Adult Medicine MCQ

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HardGeneral Internal MedicineAcute Intermittent PorphyriaRACP Adult Medicine

A 25-year-old woman presents with recurrent episodes of abdominal pain, peripheral neuropathy, and confusion. During an acute episode, her urine turns dark red-brown on standing. Urine porphobilinogen (PBG) is markedly elevated. What is the most appropriate acute treatment?

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Correct answer: C — IV haem arginate (hemin)

Markedly elevated urine PBG with neurovisceral symptoms (abdominal pain, neuropathy, psychiatric symptoms) is diagnostic of acute intermittent porphyria (AIP). IV haem arginate (haematin/hemin) is the definitive acute treatment – it suppresses ALA synthase, reducing porphyrin precursor production. IV glucose loading (10% dextrose) can be used as a temporising measure for mild attacks. Precipitating factors (drugs, fasting, alcohol, hormones) should be identified and avoided. Givosiran (siRNA targeting ALA synthase) is now available for prophylaxis.

Reference: eTG – 2025 – Haematology; BIMDG – 2021 – Porphyria Emergency Guidelines