Which type of anemia is characterized by macrocytic RBCs with megaloblastic changes?

Appeared in: NORCET 7 Prelims -2024

Explanation

Megaloblastic anemia is directly defined by the presence of large, immature red blood cell precursors (megaloblasts) in the bone marrow.
These megaloblasts mature into large red blood cells (macrocytes), which are also referred to as macroblastic RBCs.
This condition is a result of impaired DNA synthesis, which delays nuclear maturation while the cytoplasm continues to grow, leading to oversized cells.
The most common causes are deficiencies in vitamin B12 and/or folic acid.

Option A: Iron deficiency anemia is characterized by microcytic (abnormally small) and hypochromic (pale) red blood cells, which is the opposite of macroblastic.
Option B: Pernicious anemia is a specific cause of megaloblastic anemia, resulting from an autoimmune condition that prevents vitamin B12 absorption. While it does feature macroblastic cells, 'Megaloblastic anemia' is the broader and more direct classification for the hematological finding itself.
Option D: Sickle cell anemia is a genetic disorder (hemoglobinopathy) where red blood cells become rigid and sickle-shaped under hypoxic conditions. The primary abnormality is shape, not size; the cells are typically normocytic (normal-sized).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Red Blood Cell Morphology in Anemia as background academic context rather than a clinical decision trigger.
Understanding RBC morphology is crucial for nurses to interpret complete blood count (CBC) results, particularly the Mean Corpuscular Volume (MCV), which indicates RBC size.
A high MCV points towards macrocytic anemias like megaloblastic anemia, prompting further investigation into vitamin B12 and folate levels.
Nursing care for patients with megaloblastic anemia includes administering prescribed vitamin B12 injections or oral folate, providing dietary education, and monitoring for symptom improvement.

How to Approach the Question

First, identify the key term in the question: 'macroblastic RBC'. Understand that 'macro' means large.
Recall or deduce that macroblastic RBCs are abnormally large red blood cells.
Evaluate each option based on this understanding.
Option A (Iron deficiency): Associated with 'microcytic' or small cells.
Option B (Pernicious anemia): A cause of large cells, but it's a specific disease.
Option C (Megaloblastic anemia): The direct definition for anemia characterized by large cells.

Concept Tested & Keywords

Q2bJNTbnljxZ33HzFJHiJV

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed pp. 663-665, 653-655

Practise the full NORCET 7 Prelims -2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.