Which vitamin deficiency is associated with macrocytic anemia and numbness?

• A. Vitamin B12 (cobalamin) deficiency
• B. Vitamin C deficiency
• C. Vitamin D deficiency
• D. Vitamin A deficiency

Answer: (A)

Macrocytic anemia arises when red blood cell precursors can’t divide properly, a situation that occurs when DNA synthesis is impaired. Vitamin B12 is essential for this process, and its deficiency leads to larger-than-normal red cells (megaloblastic anemia). The numbness reflects nervous system involvement—B12 is crucial for maintaining myelin, so deficiency causes demyelination that can produce numbness or tingling in the extremities. The other vitamins don’t typically cause this combination: they may lead to different symptoms (scurvy with bleeding for vitamin C, bone problems for vitamin D, vision/skin issues for vitamin A) but not the macrocytosis with neurologic symptoms seen here.