Adult-Onset Hyperammonemia: Case Report and Review of Literature.

Introduction: Hyperammonemia is a life-threatening condition most associated with liver disease, though non-cirrhotic causes are increasingly recognized.

Case presentation: We report an 18-year-old female presenting with 1 week of progressive confusion, abdominal pain, and nausea. Initial evaluation showed normal routine laboratories but markedly elevated ammonia and respiratory alkalosis. She rapidly deteriorated, requiring intubation and intensive care. Ammonia peaked at 795 µg/dL and improved rapidly after urgent venous hemofiltration and medical therapy, with full neurological recovery by day 3. Further testing revealed late-onset ornithine transcarbamylase deficiency.

Conclusion: We present an algorithm for the approach to hyperammonemia and urea cycle disorders through a comprehensive review of current diagnostic and therapeutic strategies pertaining to urea cycle disorders.