Functional vitamin B12 deficiency is a consistent feature in hospital admissions for neurological disorders due to the use of nitrous oxide
Étienne Mondésert, Céline Eiden, Hélène Peyrière, Aude Formoso, L. Corti, J. Cristol, S. Badiou
Clinical Toxicology September 2, 2023 DOI: 10.1080/15563650.2023.2274282 (opens in new tab)
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Study at a glance
AI-extracted from the abstract| Characteristics | Retrospective observational study Peer reviewed |
|---|---|
| Sample size | 31 |
| Population | Patients hospitalized for nitrous oxide use at a university hospital in southern France |
| Key findings | Among 31 patients hospitalized for nitrous oxide misuse, 97% had peripheral polyneuropathy and/or myelopathy, and most showed a functional vitamin B12 deficiency: median homocysteine was 87.7 µmol/L (normal <15) and median methylmalonic acid 3.8 µmol/L (normal <0.5), while median vitamin B12 was 134.6 pmol/L. The authors argue that measuring cobalamin metabolism biomarkers can help diagnose nitrous oxide-related complications in complex cases or when patients deny use. |
Abstract
Abstract
Introduction: Misuse of inhaled nitrous oxide is a growing concern in France. It is known to alter concentrations of vitamin B12, which is required as a cofactor for methionine synthase and methylmalonyl-CoA mutase activity. Hence, measurement of the concentrations of cobalamin metabolism biomarkers, including vitamin B12, homocysteine, and methylmalonic acid, could assist in the management of patients with a complex clinical presentation or in those who deny the consumption of nitrous oxide.
Methods: We retrospectively collected clinical and biological data in patients hospitalized for nitrous oxide use in a university hospital in southern France between January 2020 and October 2022.
Results: Thirty-one patients were identified during 34 months; 79% were men with a median age of 23.7 years. Most (97%) presented with peripheral polyneuropathy and/or myelopathy. The median vitamin B12 concentration was 134.6 pmol/L, with 17 of 31 patients having values less than 145 pmol/L (the lower limit of the normal range). The median plasma folate concentration was 20.1 nmol/L, which is within the normal range. The median plasma homocysteine concentration was 87.7 µmol/L (normal range <15 µmol/L), and the median plasma methylmalonic acid concentration was 3.8 µmol/L (normal range <0.5 µmol/L).
Conclusion: Nitrous oxide use is an emerging public health problem in France, as shown by the number of patients admitted to our hospital. The presence of a functional vitamin B12 deficiency was a consistent feature that could be helpful in diagnosis in complex cases.