Abstract: FR-PO0601
Uncovering the Attack: A Case of Hereditary Coproporphyria with Life-Threatening Hyponatremia
Session Information
- Fluid, Electrolyte, and Acid-Base Disorders: Clinical - 2
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Fluid, Electrolytes, and Acid-Base Disorders
- 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Authors
- Gulden, Erin Kayleigh, San Antonio Uniformed Services Health Education Consortium, Joint Base San Antonio Fort Sam Houston, Texas, United States
- Wickham, Jesse M., San Antonio Uniformed Services Health Education Consortium, Joint Base San Antonio Fort Sam Houston, Texas, United States
- Astorga, Nestor Gerardo, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States
Introduction
Hereditary coproporphyria (HCP) results from reduced enzymatic activity of coproporphyrinogen oxidase, a catalyst in the heme pathway. The build-up of neurotoxic precursors manifests clinically as a wide spectrum of neurovisceral symptoms, including autonomic dysfunction and psychological disturbances. Diagnosis of HCP can be challenging with the non-specific presentation of this condition; however, late recognition of attacks may lead to fatal complications.
Case Description
A 20-year-old male with no medical history presented with acute encephalopathy, severe hypertension, and a serum sodium of 100. His presentation was preceded by one week of abdominal pain, constipation, and nausea. During that time, he also developed urinary hesitancy, which prompted him to drink 7.5L of water daily. Initial urine studies were consistent with syndrome of inappropriate antidiuretic hormone, (Plasma osmolality 221 mosm/kg, urine sodium 62 mosm/L, urine osmolality 811 mosm/kg), which was initially believed to be driven by nausea. The urine was dark orange in color, and urinalysis revealed 4+ urobilinogen, prompting an order for urine ALA- δ, which was elevated at 89.8. Correction of the hyponatremia required hypertonic saline infusion, urea supplementation, and fluid restriction. He was persistently tachycardic and hypertensive, which was managed with beta blockers and an angiotensin receptor blocker. Further studies for HCP were ordered to include Porphobilinogen (PBG)/creatinine ratio (40.4 mg/g) and urine PBG (28), which were also elevated. Genetic testing eventually confirmed HCP as the official diagnosis.
Discussion
Typically, SIADH is only present during acute attacks of HCP and resolves with the management of the episode. This case had unusually profound and persistent SIADH, prompting a detailed search for the underlying etiology. Furthermore, HCP has a significant impact on blood pressure and kidney function. HCP requires annual surveillance for CKD and, in some cases, medications to reduce ALA and PBG levels to slow progression.