The normal MCV is:

Appeared in: DSSSB October 2024

Explanation

Mean Corpuscular Volume (MCV) measures the average size of a red blood cell and is expressed in femtoliters (fL).
The standard reference range for a normal MCV in adults is 80 to 100 fL.
Red blood cells within this 80-100 fL range are classified as 'normocytic,' meaning they are of normal size.
This range is critical for the initial classification of anemia, distinguishing it from conditions where cells are too small (microcytic) or too large (macrocytic).

Option A: The range of 40-60 fL is incorrect. This value represents severely microcytic (abnormally small) red blood cells, not a normal size.
Option B: The range of 60-80 fL is incorrect. While closer to normal, this range indicates microcytic (abnormally small) red blood cells.
Option D: The range of 20-40 fL is incorrect. This value is extremely low and represents profoundly microcytic red blood cells, which is not compatible with normal physiology.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Normal Mean Corpuscular Volume (MCV) value as background academic context rather than a clinical decision trigger.
Nurses frequently review CBC results, and understanding the MCV is essential for identifying potential underlying causes of a patient's anemia and anticipating further diagnostic tests or treatments.
When a patient is receiving treatment for anemia (e.g., iron supplements for iron deficiency), monitoring the MCV helps the nurse assess the effectiveness of the therapy as the red blood cell size normalizes.
What if? If a patient's MCV is 115 fL (macrocytic) and they have a history of chronic alcohol use, the nurse should anticipate potential liver disease and nutritional deficiencies (like folate), not just a simple B12 deficiency. This guides patient assessment and education.

How to Approach the Question

First, identify the core of the question, which is asking for a specific normal laboratory value: Mean Corpuscular Volume (MCV).
This is a factual recall question. Access your knowledge of hematology and standard lab reference ranges.
Recall that MCV is used to classify anemia based on red blood cell size: microcytic, normocytic, and macrocytic.
Remember the key thresholds: below 80 fL is microcytic, and above 100 fL is macrocytic.
Therefore, the normal (normocytic) range must lie between these values.
Scan the options and select the one that matches the standard normocytic range, which is 80-100 fL.

Concept Tested & Keywords

QClPTAhUrsu0uTya6OBEMt

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 353-355

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 2292-2294

Practise the full DSSSB October 2024

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