Increased Fecal Porphyrins in Acute Intermittent Porphyria

Abstract

Definitive diagnosis of porphyrias may require determination of total porphyrin in urine, feces, and blood (1) and fractionation of the various urine and fecal porphyrins. Most authorities agree that fecal porphyrin fractionation is required for the differential diagnosis of porphyria cutanea tarda, variegate porphyria (VP), and hereditary coproporphyria (HCP) (1)(2). We investigated three patients who excreted excess porphobilinogen (PBG), and who therefore had one of the acute porphyrias. Additional investigation by HPLC fractionation of urine and fecal porphyrins led to a diagnosis of acute intermittent porphyria (AIP). Although total fecal porphyrin in AIP is usually thought to be within the reference interval or slightly increased and of limited assistance in the diagnosis of this type of acute porphyria (1)(2)(3), our patients had markedly increased total fecal porphyrins. Fractionation by HPLC revealed that uroporphyrin was a prominent component in all three cases. Patient A was a woman, 40 years of age, admitted to the emergency department of a tertiary teaching hospital for investigation of intractable acute abdominal pain. Patient B was a woman, 36 years of age, who was initially under the care of an orthopedic surgeon for severe back pain and was referred to a consultant physician for investigation of multiple symptoms, including urinary retention, dysuria, back pain, and depression. Patient C was a woman, 30 years of age, previously diagnosed with AIP at the age of 25 years who consulted a clinician with severe abdominal pain. She had a family history of AIP, and we had identified 15 cases of symptomatic AIP in three generations of her family previously. We investigated the metabolism of …