For megaloblastic anaemia with a normal vitamin B12 level and a low serum folate level, which treatment is appropriate?

For megaloblastic anaemia with a normal vitamin B12 level and a low serum folate level, which treatment is appropriate?

• A. Iron supplement
• B. Folic acid
• C. Vitamin B12 injections
• D. Folinic acid

Answer: (B)

When megaloblastic anemia is due to insufficient folate and the vitamin B12 level is normal, the problem is a lack of folate needed for DNA synthesis. Folate provides one-carbon units essential for thymidine and purine production, so its deficiency disrupts DNA replication in rapidly dividing cells like those in the bone marrow. Replacing folate restores these steps, normalizes DNA synthesis, and allows proper maturation of red blood cells, correcting the macrocytic anemia. Iron would not help here because this is not iron-deficiency anemia; the issue isn’t iron supply or heme production. Vitamin B12 injections aren’t needed since B12 status is adequate, and giving B12 won’t address the folate shortage. Folinic acid is a related folate form and can be used in certain contexts, but the standard and most appropriate initial treatment for isolated folate deficiency is folic acid due to its effectiveness, ease of use, and cost.

When megaloblastic anemia is due to insufficient folate and the vitamin B12 level is normal, the problem is a lack of folate needed for DNA synthesis. Folate provides one-carbon units essential for thymidine and purine production, so its deficiency disrupts DNA replication in rapidly dividing cells like those in the bone marrow. Replacing folate restores these steps, normalizes DNA synthesis, and allows proper maturation of red blood cells, correcting the macrocytic anemia.

Iron would not help here because this is not iron-deficiency anemia; the issue isn’t iron supply or heme production. Vitamin B12 injections aren’t needed since B12 status is adequate, and giving B12 won’t address the folate shortage. Folinic acid is a related folate form and can be used in certain contexts, but the standard and most appropriate initial treatment for isolated folate deficiency is folic acid due to its effectiveness, ease of use, and cost.