Pernicious anemia results in deficiency of which vitamin?

• A. Vitamin B12
• B. Vitamin C
• C. Vitamin D
• D. Vitamin A

Answer: (A)

Pernicious anemia is caused by impaired absorption of vitamin B12 due to a lack of intrinsic factor, which is produced by gastric parietal cells. Intrinsic factor is essential for vitamin B12 uptake in the terminal ileum; without it, even with adequate dietary B12, absorption fails and stores eventually run low. This deficiency disrupts DNA synthesis in rapidly dividing cells, leading to a megaloblastic, macrocytic anemia. Vitamin B12 is also important for maintaining myelin, so deficiency can cause neurological symptoms if not treated.

The other vitamins listed do not cause pernicious anemia. Vitamin C deficiency leads to scurvy with symptoms like gum disease and poor wound healing; vitamin D deficiency causes rickets or osteomalacia; vitamin A deficiency affects vision and skin health. Therefore, pernicious anemia specifically reflects a vitamin B12 deficiency.