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Authors

Peter Abdou, M3; Alec Johnson, DO; Melissa H Olken, MD, PhD, FHM, FACP Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo, MI

Introduction

Hereditary Coproporphyria is caused by a deficiency of Coproporphyrinogen Oxidase (CPOX gene), the sixth enzyme in the heme synthesis pathway. It is inherited in an autosomal dominant manner with incomplete penetrance. Prevalence is estimated at 2-5 per million population [1-2]. Certain medications, alcohol, infection, hormonal fluctuations during the menstrual cycle and other stressors may trigger attacks. Clinical symptoms can include abdominal pain, nausea, constipation, diarrhea, hypertension, seizures.

Case Presentation

A 57-year-old female presented to the emergency department with severe constant abdominal pain, nausea, and vomiting which started when she was eating fish for dinner. She reported she had “stomach problems” for at least 20 years and tried multiple therapies to no avail. She reported no recent travel. Past medical history was significant for episodic abdominal pain of undetermined origin; 6 hospital admissions, 22 ED visits, and 11 gastroenterology visits for abdominal pain, nausea, vomiting, and/or diarrhea over the past 10 years were recorded in her electronic medical record. PMH was also significant for seizures (last seizure “years ago” - unsure of date). The patient reported that one of her relatives has “stomach problems” like hers, although they do not share living space. Social history includes marijuana use. Vital signs at presentation were: HR 85, RR 16, BP 208/135. The patient was noted to be diaphoretic and had abdominal tenderness in the epigastric area. No skin abnormalities were noted. ED Labs were significant for WBC 18.3, ANC 14.5, Hb 17.1, Na 146, AG 20. No acute intra-abdominal process was identified on CT. Her acute symptoms markedly improved over her two day hospitalization with supportive treatment (IV fluids, labetalol, hydralazine). Considering this information, the internal medicine team suspected acute porphyria. When asked, the patient endorsed that the color of her urine resembled a published photo of typical acute porphyria urine (dark red). A urine sample was collected before she was discharged and was sent for porphyrin testing, which revealed a urine porphyrin profile compatible with acute intermittent porphyria, variegate porphyria, and hereditary coproporphyria. The patient was then referred to a hematologist/oncologist, who ordered a fecal porphyrin test that revealed a porphyrin profile consistent with Hereditary Coproporphyria.

Discussion

According to the American Gastroenterological Association 2023 Best Practice Guidelines for Acute Hepatic Porphyrias (AHP), “Women aged 15-50 years with unexplained, recurrent severe abdominal pain without a clear etiology after an initial workup should be considered for screening for an AHP” [3]. Treatment for patients with AHP may include IV hemin, which inhibits ALAS1 - the first and rate-limiting step of heme synthesis pathway - in order to prevent the accumulation of toxic intermediates. Treatment may also include Givosiran, an siRNA therapy that decreases production of the ALAS1 enzyme. Patients with AHP should be screened for chronic kidney disease and hepatocellular carcinoma.

References

1. Bissell DM, Anderson KE, Bonkovsky HL. Porphyria. N Engl J Med. 2017;377:862-872. [PMID: 28854095] doi:10.1056/NEJMra1608634
2. Singal AK, Anderson KE. Hereditary coproporphyria. UpToDate. Accessed at on 1 October 2024.
3. Wang B, Bonkovsky HL, Lim JK, et al. AGA clinical practice update on diagnosis and management of acute hepatic porphyrias: expert review. Gastroenterology. 2023;164:484-491. [PMID: 36642627] doi:10.1053/j.gastro.2022.11.034

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