A Triple Threat: Acute Intermittent Porphyria Presenting with SIADH and Hypertensive Encephalopathy in a Child: A Case Report

Acute intermittent porphyria (AIP) is a rare metabolic disorder affecting the production of heme resulting from a deficiency of the enzyme porphobilinogen deaminase. The patients commonly present with pain in the abdomen, hypertension, nausea, vomiting as well as peripheral motor neuropathy. Hyponatremia from Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) is a rare presentation of AIP with can lead to resistant hypertension in children, which in turn can lead to hypertensive encephalopathy an even rare finding. We present a case of a 10-year-old girl with recurrent abdominal pain, vomiting, irritability, anorexia who presented with seizures and altered mental status. Physical examination showed an altered emaciated pale appearing girl with elevated blood pressure concerning for hypertensive encephalopathy after ruling out metabolic and structural aetiologies for her seizures and delirium. Of note, her urine was dark brown with a reddish tinge, subsequent investigation revealed elevated urinary porphobilinogen (PBG) consistent with AIP. Patient also had hyponatremia determined to be due to the SIADH often associated with AIP. Hypertensive encephalopathy is a rare complication of AIP. Patient improved significantly after treatment with Glucose(500mg), Captopril(25mg), Bisoprolol(5mg), and Gabapentin.