Vitamin B12 is required for a number of metabolic processes. Which of the following lesions would NOT lead to a deficiency of this vitamin?
**Core Concept**
Vitamin B12 plays a crucial role in the metabolism of fatty acids and amino acids, as well as the synthesis of DNA and myelin. A deficiency in Vitamin B12 can lead to neurological and hematological disorders.
**Why the Correct Answer is Right**
The correct answer is a condition that does not affect the absorption or utilization of Vitamin B12. Pernicious anemia, a condition characterized by the autoimmune destruction of parietal cells in the stomach, leads to a deficiency in intrinsic factor, which is essential for Vitamin B12 absorption. This results in a deficiency of Vitamin B12. Similarly, conditions that affect the terminal ileum, such as Crohn's disease or surgical resection, can lead to malabsorption of Vitamin B12. However, conditions that do not directly impact Vitamin B12 absorption or utilization would not lead to a deficiency.
**Why Each Wrong Option is Incorrect**
**Option A:** Pernicious anemia - This condition leads to a deficiency in intrinsic factor, which is essential for Vitamin B12 absorption, resulting in a deficiency.
**Option B:** Crohn's disease - This condition can lead to malabsorption of Vitamin B12 due to damage to the terminal ileum.
**Option C:** None of the above - This is the correct answer, as none of the conditions listed lead to a deficiency of Vitamin B12.
**Clinical Pearl / High-Yield Fact**
Vitamin B12 deficiency can lead to neurological symptoms such as numbness and tingling in the hands and feet, as well as megaloblastic anemia.
**Correct Answer:** C. None of the above.