A case of functional vitamin B12 deficiency after recreational nitrous oxide use.
Damien Leleu, Damien Denimal
Biochemia medica February 15, 2024 DOI: 10.11613/bm.2024.010801 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Case study Case report Peer reviewed |
|---|---|
| Sample size | 1 |
| Population | A 22-year-old woman with recreational nitrous oxide use |
| Keywords | Homocysteine Methylmalonic acid Nitrous oxide Vitamin b12 |
| Key findings | The patient had macrocytic anemia and hypersegmented neutrophils with normal serum vitamin B12 and folate but significantly increased total homocysteine and methylmalonic acid, indicating functional vitamin B12 deficiency linked to over a year of recreational nitrous oxide use. The authors argue that diagnosing vitamin B12 deficiency in nitrous oxide users is challenging because serum B12 can be normal in a significant proportion of cases. |
Abstract
The recreational use of nitrous oxide as laughing gas becomes a real public health issue among adolescents and young adults. Chronic use is deleterious and can lead to severe neurological disorders. Nitrous oxide inactivates vitamin B12, and the functional defect of vitamin B12 plays a major role in the pathogenesis of nitrous oxide-related neurological disorders. Here we report the case of a 22-year-old woman who came to the hospital after an unexplained loss of consciousness. She exhibited typical features of vitamin B12 or folate deficiency such as macrocytic anemia and hypersegmented neutrophils. However, serum concentrations of folate and vitamin B12 were normal. In contrast, circulating concentrations of total homocysteine and methylmalonic acid were significantly increased. These results clearly indicated a defect in vitamin B12 functions. The reason for this defect was clarified when she revealed that she had been consuming nitrous oxide recreationally for over a year. The present case points out the challenges in diagnosing vitamin B12 deficiency in the context of nitrous oxide abuse due to normal concentrations of total serum vitamin B12 in a significant proportion of cases. The medical community should be aware of how difficult it can be to interpret B12 status in this specific population.