RT Journal Article SR Electronic T1 Valproate-induced fatal acute hyperammonaemia-related encephalopathy in late-onset ornithine transcarbamylase deficiency JF BMJ Case Reports JO BMJ Case Reports FD BMJ Publishing Group Ltd SP e241429 DO 10.1136/bcr-2020-241429 VO 14 IS 5 A1 Daniel Kazmierski A1 Nishant Sharma A1 Kelly O'Leary A1 Pius Ochieng YR 2021 UL http://casereports.bmj.com/content/14/5/e241429.abstract AB Ornithine transcarbamylase (OTC) deficiency is a genetic disorder of the urea cycle characterised by deficiency in the enzyme OTC, resulting in an accumulation of ammonia. Valproic acid (VPA), a commonly used medication in the treatment of neurologic and psychiatric conditions, has been known to cause episodes of acute hyperammonaemia in patients with OTC deficiency. We present the case of a 29-year-old man with a long history of non-specific psychiatric disorders, who suffered from a hyperammonaemic crisis following the administration of VPA, leading to the diagnosis of OTC deficiency. The patient’s hospital course was complicated by progressive cerebral oedema, which resulted in worsening encephalopathy, seizures and death. We discuss the pathophysiology of hyperammonaemia in OTC deficiency, and various management strategies, including lactulose, levocarnitine, scavenger therapy and haemodialysis.