A mysterious case with abdominal pain and syndrome of inappropriate anti-diuretic hormone secretion

Abstract

Background. Acute intermittent porphyria (AIP) is a rare, hereditary, metabolic disease caused by a defect in heme biosynthesis. Hormonal changes may trigger porphyria attacks. Case. Here we present a 17-year-old adolescent refugee mother who applied to the pediatric emergency department with the complaint of diffuse abdominal pain at puerperium. The patient was hypertensive, and had convulsions after admission. Hyponatremia (serum sodium; 121 meq/L) was detected, and syndrome of inappropriate anti-diuretic hormone secretion (SIADH) was found to be the cause of hyponatremia which responded well to fluid restriction. Infectious, autoimmune and toxicologic laboratory work-up did not reveal any specific pathologies. Despite prompt utilization of analgesic treatment, the patient continued to have unbearable abdominal pain. The preference of prone position to relieve the pain and the family history of a mother who had died with similar symptoms, led us to the diagnosis of AIP. Genetic analysis showed a heterozygous mutation in hydroxymethylbilane synthase (HMBS) gene (c160+6T>A) which confirmed our diagnosis. Conclusion. Acute porphyrias should be considered in differential diagnosis of abdominal pain, especially when there are accompanying symptoms like hyponatremia, seizures, mental changes and hypertension.