Snapshot An 28-year-old woman presents with colicky abdominal pain. She fidgets around and sporadically has weeping spells, reports tingling in her fingers and toes, and has no significant past medical history with no official psychiatric history. On physical exam, she is found to be tachycardic. Her abdominal exam is normal, without tenderness on palpation. Neurologic exam is normal. Abdominal radiographs are completely normal. Porphobilinogen was found to be positive in high titers in her urine. Introduction Clinical definition acute intermittent porphyria (AIP) is an inherited metabolic disease resulting from deficiency in the heme synthesis pathway enzyme porphobilinogen deaminase (PBD) Epidemiology incidence AIP is the most common type of acute porphyria still relatively rare demographics women > men 20-40 years of age risk factors female gender Pathophysiology pathobiology deficiency of PBD, step 3 in heme pathway attacks are precipitated by an exposure exposure increases demand of the heme pathway this results in accumulation of intermediates aminolevulinic acid (ALA) and porphobilinogen (PBG) both are neurotoxic precipitating factors most common drugs cytochrome P-450 inducers anticonvulsants oral contraceptive pills smoking infection starvation fluctuating hormones (menstrual cycle in women) Genetics inheritance pattern autosomal dominant mutations HMBS (also known as PBGD), encoding PBD Prognosis most patients fully recover < 5% have recurrence Presentation Symptoms often nonspecific and vague primary symptoms (5 P’s) severe abdominal pain without tenderness on palpation neurological symptoms polyneuropathy seizures, weakness, and paralysis psychiatric symptoms anxiety and insomnia port wine-colored urine precipitated by an exposure Physical exam vitals tachycardia hypertension the rest of physical exam is often normal Imaging Radiographs abdominal radiography indications often initially obtained due to nonspecific nature of symptoms findings normal Studies Labs serum studies may see hyponatremia urine studies ↑ PBG, aminolevulinic acid Differential Small bowel obstruction tenderness on palpation Lead poisoning no elevated PBG in urine Treatment Remove precipitating factors Medical heme and glucose indications for symptomatic attacks to prevent permanent neurologic damage Complications Chronic neuropathic pain treatment gabapentin