Metabolic encephalopathy caused by nitrous oxide ('laughing gas') induced hyperammonaemia
Marissa Ginette Danielle Vive1, Galia Valentinova Anguelova2, Sjoerd Duim3
1Internal Medicine, Haaglanden Medisch Centrum, The Hague, South-Holland, The Netherlands marissavive@gmail.com.
Abstract:
A 26-year-old man presented at the emergency department with confusion and decreased consciousness after several days of vomiting. In the preceding 6 months, he had used a 2-litre tank of nitrous oxide (N2O) weekly. His metabolic encephalopathy was caused by hyperammonaemia which probably resulted from interference of N2O-induced vitamin B12 deficiency with ammonia degradation. A catabolic state might have contributed to the hyperammonaemia in this case. After treatment with vitamin B12 and lactulose, both his consciousness and hyperammonaemia improved. He reported no residual complaints after 3 months of follow-up. Since N2O is increasingly used as a recreational drug, we recommend considering hyperammonaemia as a cause of metabolic encephalopathy in cases of N2O use and altered mental status.
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