Acute intermittent porphyria (AIP)
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A young woman taking oral contraceptives develops severe abdominal pain, vomiting, and constipation. She becomes confused and has a seizure. Urine turns dark on standing. PBG is elevated.
AD (low penetrance); HMBS (hydroxymethylbilane synthase/PBG deaminase)
- Acute attacks triggered by drugs (P450 inducers), fasting, hormones, stress
- Abdominal pain (severe, colicky)
- Neuropsychiatric symptoms (confusion, anxiety, seizures)
- Peripheral neuropathy
- Dark/red urine (on standing)
- No photosensitivity
- Urine PBG elevated during attack
- IV hemin, glucose loading, avoid triggers
"Porphyria" is Greek for "purple": urine turns dark red/purple on standing due to porphobilinogen (PBG) oxidation.
AIP has Abdominal pain, but NO photosensitivity: this distinguishes AIP from other porphyrias (like porphyria cutanea tarda). The "5 P's" of acute porphyria attacks: Pain (abdominal), Polyneuropathy, Psychological disturbance, Port-wine colored urine, Precipitated by drugs/fasting/hormones.