Snapshot A 32-year-old woman presents to the psychiatric emergency room for uncooperative behavior and hysteria. She complains of abdominal pain. While being evaluated, she had a generalized tonic-tonic seizure. She has no family or personal history of seizures. Her serum studies ruled out any metabolic abnormalities that may cause seizures. Neurologic exam showed extensive peripheral neuropathy. Urine showed high titers of porphobilinogen. Introduction Clinical definition acute intermittent porphyria (AIP) is an inherited metabolic disease resulting from deficiency in the heme synthesis pathway porphobilinogen deaminase (PBD) Epidemiology Incidence AIP is the most common type of acute porphyria but still relatively rare 0.13 per year per million persons Demographics women > men 20-40 years of age Risk factors female gender ETIOLOGY Pathophysiology pathobiology deficiency of porphobilinogen deaminase (step 3 in heme pathway, see illustration) attacks are precipitated by an exposure login to view 11 more bullets Genetics inheritance pattern autosomal dominant mutations HMBS (aka PBGD), encoding PBD Presentation Symptoms often nonspecific and vague primary symptoms (5 P’s) severe abdominal pain without tenderness on palpation neurological symptoms login to view 2 more bullets psychiatric symptoms login to view 1 more bullet port wine-colored urine precipitated by an exposure vomiting constipation Physical exam vitals tachycardia hypertension neurologic signs in severe attacks loss of tendon reflexes motor stiffness/paralysis the rest of physical exam is often normal Imaging Radiographs abdominal radiography indication login to view 1 more bullet findings login to view 1 more bullet Studies Labs serum studies may see hyponatremia urine studies ↑ PBG, aminolevulinic acid, and uroporphyrin III stool studies no fecal porphyrin login to view 1 more bullet Differential Small bowel obstruction tenderness on palpation Lead poisoning no elevated PBG in urine Treatment Remove precipitating factors Medical heme infusions indication login to view 1 more bullet glucose indications login to view 2 more bullets requires close monitoring of serum sodium to exclude hyponatremia Complications Chronic neuropathic pain treatment gabapentin Prognosis Most patients fully recover < 5% have recurrence