SAT-219 The Enigma of Porphyria: Untangling a Web of Endocrine Imbalances

Abstract Disclosure: M. Hadeed: None. G. Rivera Rodriguez: None. M.C. Franco Liñan: None. L. Perez-Burnes: None. C. Bustamante Escobar: None. Acute Porphyrias are rare metabolic disorders caused by enzyme deficiencies in the heme synthesis pathway, leading to the accumulation of toxic porphyrin precursors. Acute Intermittent Porphyria (AIP), the most common hepatic form of porphyria, results from a deficiency in porphobilinogen deaminase. Accumulating porphyrin precursors, such as delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) induce oxygen-free radicals that disrupt myelin formation in the central nervous system. Hormonal imbalances may also occur due to the relationship between the nervous and endocrine systems during acute porphyria attacks. ALA is primarily responsible for the neuropsychiatric and visceral manifestations seen in AIP, including abdominal pain, neuropathy, seizures, behavior changes, and hyponatremia. Autonomic hyperactivity is seen as hypertension and tachycardia. We identified a case of AIP in a 16-year-old female who reported persistent myalgia after emergency contraceptive use two weeks prior, who had similar pain approaching the luteal phase of her menstrual cycle. Laboratory tests revealed hyponatremia (Na 123 mmol/L), hypocalcemia (7.5 mg/dL), low vitamin D, and elevated uric acid (7.4 mg/dL). Further studies showed a serum osmolality of 254 mOsm/kg, urine osmolality of 627 mOsm/kg, and urine sodium of 102 mEq/L, consistent with Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH). Although other electrolyte abnormalities are not commonly described, SIADH is one of the most common manifestations of AIP, typically in association with abdominal pain. The patient also developed a hypertensive crisis, indicating autonomic hyperactivity. A urine sample exposed to direct sunlight showed color changes from yellow to red-brown and had elevated levels of porphobilinogen (85.7 µmol/L; normal ≤ 1.0 µmol/L). The total plasma porphyrin level (1.7 mcg/dL; normal ≤1.0 mcg/dL) confirmed the diagnosis of AIP. Genetic testing identified a variant in the HMBS gene compatible with AIP. AIP is frequently misdiagnosed due to its variable presentations. In patients with abdominal pain, electrolyte disturbances and autonomic symptoms associated with acute hormonal changes, AIP should be considered. This pattern may reflect the complex interaction between the endocrine and nervous systems during AIP attacks. Presentation: Saturday, July 12, 2025