Megaloblastic Anemia is caused by?

NIMHANS Nursing Officer - 2019

Pharmacology

Medium

Appeared in: NIMHANS Nursing Officer - 2019

Explanation

Folic acid (a B vitamin) is essential for the synthesis of DNA, which is required for the maturation of red blood cells.
A deficiency in folic acid impairs DNA synthesis, leading to asynchronous maturation where the cell cytoplasm matures faster than the nucleus.
This results in the production of large, immature, and dysfunctional red blood cells called megaloblasts, leading to megaloblastic anemia.
Common causes of folate deficiency include poor dietary intake (especially in alcoholics and the elderly), malabsorption syndromes, and increased demand during pregnancy.

Option A: This is also a correct cause of megaloblastic anemia, which makes the question ambiguous. Vitamin B12 deficiency leads to the same hematological picture as folate deficiency.
Option B: Iron deficiency does not cause megaloblastic anemia. It disrupts hemoglobin synthesis, not DNA synthesis.
Option D: Vitamin C (ascorbic acid) deficiency is not a cause of megaloblastic anemia. Its primary role is in collagen synthesis and as an antioxidant.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Causes and pathophysiology of megaloblastic anemia as background academic context rather than a clinical decision trigger.
It is crucial for nurses to identify patients at high risk for folate deficiency, such as pregnant women, individuals with alcohol use disorder, and those with malabsorptive diseases.
A critical patient safety consideration is to never treat megaloblastic anemia with folic acid alone until Vitamin B12 deficiency has been definitively ruled out. Doing so can correct the anemia (the hematologic signs) but mask the underlying B12 deficiency, allowing irreversible neurological damage to progress.
What if? If a patient with known megaloblastic anemia starts complaining of new-onset tingling in their feet and unsteadiness, the nurse must immediately suspect an underlying Vitamin B12 deficiency and escalate to the provider for further testing (serum B12, MMA levels), as folate supplementation alone would be dangerous.

How to Approach the Question

First, identify the core concept in the question stem: 'Megaloblastic Anemia'.
Recall the two primary causes of megaloblastic anemia: Vitamin B12 deficiency and Folic acid deficiency. Both lead to impaired DNA synthesis.
Analyze the options provided. Notice that both 'Deficiency of Vitamin B12' (A) and 'Folic acid deficiency' (C) are listed.
Recognize that this is a flawed question with two correct answers. In such a scenario on an exam, you must choose the 'best' fit or what might be the intended answer. Both are equally valid causes.
Evaluate the distractors. 'Iron deficiency' causes microcytic anemia, and 'Vita-C deficiency' causes scurvy. These are clearly incorrect.
Since both A and C are correct, understanding the nuances is key. Without further information (like neurological symptoms), either could be the answer. For this question, we select one and acknowledge the ambiguity in the rationale.

Concept Tested & Keywords

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