Megaloblastic anemia occurs due to deficiency of :

IGNOU PB. Bsc. Nsg. Entrance-2025

Medical & Surgical Nursing

Easy

Appeared in: IGNOU PB. Bsc. Nsg. Entrance-2025

Explanation

Folic acid (Vitamin B9) is a primary cause of megaloblastic anemia.
It is essential for the synthesis of thymidine, a component of DNA. Its deficiency directly impairs cell division, leading to the formation of large, immature red blood cells (megaloblasts).
While Vitamin B12 deficiency also causes megaloblastic anemia, folic acid deficiency is a direct and common nutritional cause.
The underlying defect in megaloblastic anemia is impaired DNA synthesis, for which both folate and vitamin B12 are essential.

Option A: Although Vitamin B₁₂ deficiency is a correct cause of megaloblastic anemia, the question is structured to have one best answer. Both B12 and Folic acid are correct, indicating a potentially flawed question. In many contexts, Folic acid is considered a more direct cause related to DNA synthesis block.
Option B: Iron deficiency leads to microcytic, hypochromic anemia, which is characterized by small and pale red blood cells due to insufficient hemoglobin synthesis.
Option D: Pyridoxine (Vitamin B6) deficiency is associated with sideroblastic anemia, a disorder of heme synthesis that leads to iron accumulation in the mitochondria of red blood cell precursors.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Causes of Megaloblastic Anemia as background academic context rather than a clinical decision trigger.
It is critically important for nurses to understand that while both Vitamin B12 and Folic Acid deficiencies cause megaloblastic anemia, they are not interchangeable.
Treating a Vitamin B12 deficient patient with only folic acid can correct the anemia (the blood picture may improve) but will not address the B12 deficiency. This can lead to the progression of irreversible neurological damage.
Therefore, when megaloblastic anemia is diagnosed, it is essential to determine the specific vitamin deficiency before initiating treatment.

How to Approach the Question

First, identify the core concept of the question: the cause of 'megaloblastic anemia'.
Recall the definition of megaloblastic anemia: a macrocytic anemia resulting from impaired DNA synthesis.
Systematically evaluate each option based on your knowledge of hematology and nutrition.
Recognize that both Vitamin B12 and Folic Acid are well-known causes. This indicates a potential ambiguity or a 'best-fit' question.
Recall the specific roles: Folic acid is a direct building block for DNA, while B12 is a cofactor that enables folate to be used. Both lead to the same hematological outcome.
Eliminate the clearly incorrect options: Iron (causes microcytic anemia) and Pyridoxine (causes sideroblastic anemia).

Concept Tested & Keywords

qSEdkHDeohPr4yg7Eh17i

E6 Medicine Davidson Principles Practice 24e p. 963-965

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 657-659

E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY p. 104-106