Question of the Day – Friday, October 14, 2022
What is the treatment for chronic toxicity from nitrous oxide abuse? High dose intramuscular vitamin B12 supplementation. A typical regimen is 1000 mcg IM daily for 14 days, followed by 1000 mcg IM weekly for four weeks, and then extended to monthly. Cyanocobalamin has generally…
Question of the Day – Thursday, October 13, 2022
Patients with subacute combined spinal cord degeneration (SCD) from chronic nitrous oxide abuse will often have elevated levels of methylmalonic acid and homocysteine. Which is more specific for B12 deficiency? MMA elevation is more specific for B12 deficiency because homocysteine may be elevated with folate…
Question of the Day – Friday, October 7, 2022
Nitrous oxide causes a functional vitamin B12 deficiency by what mechanism? Irreversible oxidation of the central cobalt ion from its monovalent to divalent state, rendering B12 inactive. Methylcobalamin and adenosylcobalamin, the activated forms of Vitamin B12, are necessary cofactors for two essential enzymes involved in…