What neurologic finding helps differentiate folate deficiency from B12 deficiency?

• A. Neurologic signs suggest B12 deficiency; folate deficiency typically lacks neurologic signs
• B. Folate deficiency has prominent neuropathy; B12 does not
• C. Both have identical neurologic manifestations
• D. Folate deficiency causes seizures

Answer: (A)

Neurologic involvement distinguishes B12 deficiency from folate deficiency. B12 deficiency can cause demyelination in the central nervous system, leading to numbness or tingling, gait disturbance, coordination problems, weakness, and cognitive changes. Folate deficiency, while it produces megaloblastic anemia from impaired DNA synthesis, typically does not cause these neurologic signs. Therefore, the presence of neurologic symptoms points to B12 deficiency, whereas their absence makes folate deficiency more likely. (Note: treating with folate in a patient with concurrent B12 deficiency can mask the anemia without addressing the neurologic damage.)