Acute Intermittent Porphyria (AIP)

Etiology

  • A family of uncommon genetic disorders associated w/abnormalities in heme biosynthesis in the liver
  • Dysfunctional or lower than normal levels of enzyme → accumulation of precursor proteins
  • Different symptoms/presentations based on which enzymes deficient → build up of different precursor proteins
  • AIP is most common of the acute porphyrias
  • Interestingly, most patients w/the genetic defect don't manifest the disease - indicating that other factors contribute

Risk Factors

  • 90% women
  • Age 18-45
  • Attacks triggered by meds (multiple), starvation/decreased caloric intake (low carbs), smoking, etoh
  • + family history

Symptoms

  • Seizure in 20%
  • Episodic bouts of otherwise unexplained symptoms related to neuro-toxicity of built up precursor protein
  • Anxiety and insomnia often precursor sx prior to attack
  • During attack, symptoms include: severe abd pain, agitation/confusion, nausea, vomiting, fatigue, limb pain, motor and sensory neuropathy
  • Often history of prior unexplained episodes, leading to concern about malingering or drug seeking
  • Duration of symptoms (typically < 1-2w) and time between attacks vary
  • Neurological deficits (e.g. foot or wrist drop) resolve w/time (up to 1y)

Physical Exam Findings

  • Episodic htn, tachycardia
  • Generalized muscle weakness
  • Abdominal pain w/normal exam
  • Sensory loss and/or motor weakness that follows peripheral nerve pattern

Tests