Nitrous oxide–induced vitamin B12 deficiency

Today we discussed the case of a young man with recent use of Whippets who presented with acute onset bilateral lower extremity and upper extremity numbness and paresthesias, found to have Vitamin B12 deficiency despite lack of anemia or macrocytosis.

We learned that Nitrous Oxide acts by direct depletion of Vitamin B12 as it irreversibly binds to cobalt ions of vitamin B12 and inactivates it. In turn the pathways that rely on Vitamin B12 in order to synthesize DNA, RNA and myelin are disrupted, leading to demyelination and damage in the dorsal columns.