Acute Intermittent Porphyria

Epidemiology

  • xxx

Etiology

  • Autosomal dominant

Precipitating Factors for Attacks

  • Infection:
  • Surgery:
  • Drugs
    • Phenobarbital
    • Sulfonamides
    • Chlordiazepoxide
    • Griseofulvin
    • Phenytoin
    • Sulfonylureas
  • Low Calorie Diet/Dieting:
  • Endogenous/Exogenous Gonadal Steroids:

Physiology

  • Neuropathy -> chronic hypoventilation

Pathology

  • xxx

Diagnosis

  • PFT’s:
  • Transdiaphragmatic pressure: using NG balloon (Pga-Pes)/ normal change >25 cm H2O (referenced to TLC), usually 2-20 cm H2O in bilateral paralysis
  • CXR/Chest CT patterns:
    • Normal CXR: usually

Clinical

Pulmonary Manifestations

  • [[Chronic Hypoventilation]]: due to bulbar manifestations

Cardiac Manifestations

  • Persistent Tachycardia:

GI Manifestations

  • Abdominal pain:
  • Vomiting:

Neuro Manifestations

  • Psychiatric:
  • Peripheral (motor> sensory) neuropathy
    • Affects UE first
    • Markedly decreased DTR’s
  • Seizures (see [[Seizures]])

Treatment

  • Avoidance of offending drugs: see Pathogenesis
  • Carbohydrate loading (>200 g carbo with >100 g protein): to inhibit DLAS enzyme
  • Supportive: mechanical ventilation (if needed)
  • IV Hemin (for severe cases): inhibits DLAS

References

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