Makindo Medical Notes

Related Subjects: |Acute Porphyrias |Variegate Porphyria |Acute Intermittent Porphyria (AIP) |Porphyria Cutanea Tarda (PCT) |Porphyria Testing

🌟 Acute Intermittent Porphyria (AIP) is the most common acute porphyria. It is ~5x more common in females, typically presenting between ages 15–30. Historically known as “the porphyria of King George.”

🧾 About

• Amoxicillin ✅ and opiates ✅ are thought to be safe in porphyria.
• Characterised by defective haem biosynthesis.

🧬 Aetiology

• Autosomal dominant disorder due to ↓ activity of porphobilinogen (PBG) deaminase.
• Results in accumulation of neurotoxic intermediates (PBG, δ-ALA).

⚡ Precipitants of Acute Attacks

• Fasting or surgery (catabolic stress).
• Drugs 🚫: phenobarbitone, sulphonylureas, oestrogens, OCP, alcohol.
• Other: infections, hormonal changes, stress.

🤒 Clinical Features

• Severe central abdominal pain (95% of attacks).
• GI upset: nausea, bilious vomiting, constipation/diarrhoea.
• Hypertension + tachycardia (autonomic overactivity).
• Peripheral neuropathy → motor weakness, foot drop, cranial nerve involvement.
• CNS: seizures, psychiatric disturbance, confusion, hallucinations.
• Wine-red urine during attacks (due to PBG auto-oxidation).

🚫 Drugs to avoid: Diclofenac, Alcohol, OCP, HRT, TCAs, Benzodiazepines, Barbiturates, Halothane, Cephalosporins, Sulfonamides, Macrolides, Tetracyclines, Rifampicin, Trimethoprim, Chloramphenicol, Metronidazole, ACEI, CCB, Statins, Anticonvulsants, Furosemide, Sulfonylureas, Lidocaine, Gold salts, Antihistamines, Amphetamines.

🔑 The 6 Ps of AIP

• Porphobilinogen deaminase ↓
• Pain in abdomen
• Pee discolouration (dark red urine 🍷)
• Psychiatric symptoms
• Peripheral neuropathy
• Precipitated by drugs, alcohol, Pill (OCP)

🧪 Investigations

⚠️ All samples must be protected from light.

• Bloods: Hyponatraemia common during attacks.
• Raised urinary δ-ALA and PBG (especially during attacks).
• Urine often turns port-wine colour on standing.
• Collection bottles:
  • Blood – Purple (EDTA)
  • Urine – White (plain 20 ml universal)
  • Faeces – Blue (faecal 20 ml universal)

💊 Management

• Refer/liaise with the National Acute Porphyria Service (NAPS).
• Remove precipitants (stop unsafe drugs, correct fasting).
• IV glucose infusion (to reduce haem precursor synthesis).
• IV haem arginate (hemin) in severe attacks.
• Supportive care: fluids, pain relief (safe opiates), anti-hypertensives if needed.

📚 References

• Best practice guidelines on clinical management of acute attacks of porphyria (2013)