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, in particular anti-seizure), starvation/decreased caloric intake (low carbs), smoking, etoh, infections
+ family history
Symptoms
Seizure in 20%
Episodic bouts of otherwise unexplained symptoms related to neuro-toxicity of built up precursor protein; some report chronic baseline pain
Anxiety and insomnia often precursor sx prior to attack
During attack, symptoms include: severe abd pain, constipation, agitation/confusion, nausea, vomiting, fatigue, limb pain, motor and sensory neuropathy
Sometimes purple colored urine
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)
Lead poisoning can affect enzymes involved in heme synthesis, mimicking AIP
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
Often hyponatremia that isn't otherwise explained
Elevated urine porphobilinogen, in particular during an attack
Lead level to assure toxicity not the primary problem (i.e. mimic of AIP)