Rosh Psychiatry Board Practice Exam

What reaction is responsible for the formation of methemoglobinemia from amyl nitrite exposure?

1. Dephosphorylation

2. Glycolysis

3. Oxidation

4. Phosphorylation

The correct answer is: Oxidation

Methemoglobinemia results from the oxidation of iron in hemoglobin from the ferrous (Fe2+) state to the ferric (Fe3+) state. This process is specifically triggered by exposure to agents like amyl nitrite, which acts as an oxidizing agent. When hemoglobin is oxidized to methemoglobin, it can no longer bind oxygen effectively, leading to decreased oxygen delivery to tissues and resultant symptoms of hypoxia. In the context of amyl nitrite, it is important to understand that the oxidation process disturbs the normal transport and release of oxygen in the bloodstream. While other biological processes, such as glycolysis or phosphorylation, play significant roles in cellular metabolism, they are not directly involved in the formation of methemoglobinemia. Instead, the primary mechanism at work here is the oxidative conversion of hemoglobin to methemoglobin, making oxidation the correct answer in this scenario.