Severe Hyponatremia With Partial Hypoadrenalism in Acute Porphyria

Background: Hyponatremia is the most common electrolyte-abnormality in hospitalized-patients, it increases likelihood of hospital death up-to 50% when serum Na<120mEq/L. Syndrome of inappropriate ADH secretion (SIADH) is the most common cause of hyponatremia in hospital inpatients. Clinical Case: 29 years-old woman, hospitalized several times due to severe hyponatremia of 103mEq/L; Admissions were accompanied by severe abdominal-pain and vomiting. She complained of severe premenstrual syndrome with severe abdominal pain and was hospitalized twice after intrauterine insemination. She was euvolemic and due to high urinary-sodium was diagnosed with SIADH. Brain MRI, chest x-ray, thyroid-function test, and 1-mcg ACTH-test were normal. Insulin Tolerance Test for hypoadrenalism was abnormal with cortisol levels of 14.2mcg/dl and 40mg/dl glucose. She was instructed to take strong analgesics and prednisone during attacks, this did not prevent hyponatremia. Finally, due to recurrent abdominal pain, porphyria workup was done and was positive. There are 30 case-reports of porphyria and SIADH. Porphyrias are a group of 8 inherited metabolic-disorders of heme biosynthesis, often classified as hepatic or erythropoietic according to the organ in which heme precursors accumulate. Acute intermitted porphyria is estimated in ~1/75000 people of European descend, yet clinical disease is seen in ~10% of carriers. Attacks present with severe abdominal-pain, nausea, vomiting, constipation, occasionally excretion of red colored urine and signs of increased sympathetic activity. Hyponatremia due to SIADH develops in 40% of patients and can lead to convulsions. Porphyria can exacerbate by several drugs, infectious processes, alcohol, and menstruation-induced hormonal-changes. Diagnosis is made by excess of urine porphobilinogen and 5-aminolaevulinic-acid. Treatment should include avoidance of precipitating factors and hemein infusions. Conclusions: SIADH is considered responsible for the hyponatremia seen in porphyria patients. Our patient showed an abnormal cortisol response to Insulin induced hypoglycemia, in accordance to (1) that demonstrated decreased output of cortisol and metabolites in porphyria patients secondary to decreased hemoproteins, as p450 cytochromes. Importantly, levels of endogenous hormones, particularly progesterone, can trigger an attack especially in luteal phase and in clomiphene citrate administration.1. Pozo et al Orphanet Journal of Rare Diseases 2014