{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,15]],"date-time":"2026-05-15T16:55:11Z","timestamp":1778864111249,"version":"3.51.4"},"reference-count":9,"publisher":"BMJ","issue":"11","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2019,11,5]]},"published-print":{"date-parts":[[2019,11]]},"abstract":"<jats:p>A 26-year-old man presented at the emergency department with confusion and decreased consciousness after several days of vomiting. In the preceding 6\u2009months, he had used a 2-litre tank of nitrous oxide (N<jats:sub>2<\/jats:sub>O) weekly. His metabolic encephalopathy was caused by hyperammonaemia which probably resulted from interference of N<jats:sub>2<\/jats:sub>O-induced vitamin B<jats:sub>12<\/jats:sub> deficiency with ammonia degradation. A catabolic state might have contributed to the hyperammonaemia in this case. After treatment with vitamin B<jats:sub>12<\/jats:sub> and lactulose, both his consciousness and hyperammonaemia improved. He reported no residual complaints after 3\u2009months of follow-up. Since N<jats:sub>2<\/jats:sub>O is increasingly used as a recreational drug, we recommend considering hyperammonaemia as a cause of metabolic encephalopathy in cases of N<jats:sub>2<\/jats:sub>O use and altered mental status.<\/jats:p>","DOI":"10.1136\/bcr-2019-232163","type":"journal-article","created":{"date-parts":[[2019,11,26]],"date-time":"2019-11-26T04:45:27Z","timestamp":1574743527000},"page":"e232163","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":4,"title":["Metabolic encephalopathy caused by nitrous oxide (\u2018laughing gas\u2019) induced hyperammonaemia"],"prefix":"10.1136","volume":"12","author":[{"given":"Marissa Ginette Danielle","family":"Vive","sequence":"first","affiliation":[{"name":"Internal Medicine, Haaglanden Medisch Centrum, The Hague, South-Holland, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Galia Valentinova","family":"Anguelova","sequence":"additional","affiliation":[{"name":"Neurology, Haaglanden Medisch Centrum, The Hague, South-Holland, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sjoerd","family":"Duim","sequence":"additional","affiliation":[{"name":"Clinical Chemistry, Haaglanden Medisch Centrum, The Hague, South-Holland, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Herman Marcel Andr\u00e9","family":"Hofstee","sequence":"additional","affiliation":[{"name":"Internal Medicine, Haaglanden Medisch Centrum, The Hague, South-Holland, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2019,11,25]]},"reference":[{"key":"2025082710184432000_12.11.e232163.1","doi-asserted-by":"crossref","first-page":"790","DOI":"10.1016\/j.yrtph.2015.10.017","article-title":"Recreational nitrous oxide use: prevalence and risks","volume":"73","author":"van Amsterdam","year":"2015","journal-title":"Regul Toxicol Pharmacol"},{"key":"2025082710184432000_12.11.e232163.2","doi-asserted-by":"crossref","unstructured":"Ehirim EM , Naughton DP , Petr\u00f3czi A . 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