Acute intermittent porphyria
- Acute Intermittent Porphyria is a disorder caused by the inability to produce heme, a component of hemoglobin in red blood cells.
- The defective enzyme is porphobilinogen deaminase.
- Patients typically present with dark urine, abdominal pain, and psychiatric disturbances
- Metabolic stress and starvation
- CYP450 Inducers: sulfonamides, barbiturates, rifampin or metoclopramide
- Gastrointestinal symptoms
- Acute abdominal pain (85-90% of attacks)
- Port wine-colored urine
- Agitation, confusion, combativeness, seizure
Extra-abdominal Sources of Abdominal pain
- Aortic Dissection
- Testicular Torsion
- Herpes Zoster
- Muscle spasm
- Spinal pathology
- Strep Pharyngitis (peds)
- ETOH Ketoacidosis
- Sickle Cell Crisis
- Methanol Poisoning
- Heavy Metal toxicity
- Addison's disease
- Paroxysmal nocturnal hemoglobinuria
- Black widow spider bite
Consider porphyria in patients with abdominal pain that is unexplained after an initial workup has excluded common causes (appendicitis, cholecystitis, pancreatitis, etc).
- Spot urinary porphobilinogen (sendout at most hospitals)
- Normal = 0-4mg/day
- acute attack, spot urine can be 20-200mg/L
- Recurrent attacks in a patient with proven acute porphyria are usually similar and can be diagnosed on clinical grounds without biochemical reconfirmation.