A patient's blood report showing MCV = 76 fL visits the OPD. Which of the following conditions is most likely responsible for this result?

A. Iron deficiency anemia

B. Vitamin B12 deficiency

C. Thalassemia

D. Lead poisoning

1. A

   A & B

2. B

   B & D

3. C

   A, C

4. D

   A, C, D

Appeared in: INI-CET EXAM -2025

Explanation

• An MCV of 76 fL is below the normal range of 80-100 fL, indicating microcytic anemia, which is characterized by abnormally small red blood cells.
• Microcytic anemia results from conditions that impair the synthesis of hemoglobin, the oxygen-carrying protein in red blood cells.
• Iron deficiency (A) is the most common cause, as iron is a crucial component of the heme group in hemoglobin.
• Thalassemia (C) is a genetic disorder that causes reduced production of globin chains, another key part of hemoglobin, leading to microcytosis.
• Lead poisoning (D) interferes with multiple enzymes in the heme synthesis pathway, which also results in microcytic anemia.

Why Other Options Were Wrong

• Option A: This option incorrectly includes Vitamin B12 deficiency (B).
• Option B: This option incorrectly includes Vitamin B12 deficiency (B).
• Option C: This option is incomplete. While both iron deficiency (A) and thalassemia (C) cause microcytic anemia, it omits lead poisoning (D), which is also a valid cause presented in the options.

Related Visual

• Visual 1: Diagram: Comparison of red blood cell sizes, showing the smaller size in microcytic anemia versus normocytic and macrocytic anemia.
• Visual 2: Flowchart: Diagnostic algorithm for anemia starting with the MCV value to differentiate between microcytic, normocytic, and macrocytic types.

Clinical Relevance

• Nursing practice connection: Prioritize focused assessment, early escalation, and real-time monitoring when managing Differential diagnosis of microcytic anemia based on Mean Corpuscular Volume (MCV) in acute care settings.
• The MCV is a critical initial parameter in a complete blood count (CBC) that helps a nurse and physician narrow down the potential causes of a patient's anemia.
• Based on a low MCV result, a nurse should anticipate follow-up orders for more specific diagnostic tests, such as a serum iron panel (ferritin, TIBC), hemoglobin electrophoresis (for thalassemia), or a blood lead level test.
• Patient education is key. A nurse may need to explain the need for further testing and potential treatments, such as iron supplementation for iron deficiency or dietary changes.

How to Approach the Question

• First, identify the key lab value provided in the question: MCV = 76 fL.
• Recall the normal reference range for MCV, which is approximately 80-100 fL.
• Classify the patient's result. Since 76 fL is below 80 fL, this indicates microcytic anemia.
• Next, evaluate each of the four conditions (A, B, C, D) to determine which ones are known causes of microcytic anemia.
• Recall or deduce that iron deficiency, thalassemia, and lead poisoning all disrupt hemoglobin synthesis, leading to small red cells (microcytosis).
• Recognize that Vitamin B12 deficiency affects DNA synthesis and cell division, leading to large red cells (macrocytosis), and therefore can be eliminated.

Concept Tested & Keywords

• Concept Tested: Differential diagnosis of microcytic anemia based on Mean Corpuscular Volume (MCV).
• Stem keywords: MCV, 76 fL, blood report
• Lead-in keywords: most likely responsible
• Clinical cues: MCV = 76 fL indicates microcytic anemia, as the normal range is 80-100 fL.

Question ID

Qru8bSX-0Jg0CEYeyUs3xG

Copy ID