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Yves Bikorimana։ Normal MCV Doesn’t Always Mean Normal RBCs
Apr 1, 2026, 12:37

Yves Bikorimana։ Normal MCV Doesn’t Always Mean Normal RBCs

Yves Bikorimana, CEO at MedData – Rwanda and Lab Scientist at The University Teaching Hospital of Kigali – Chuk, shared a post on LinkedIn:

”A normal Mean Corpuscular Volume (MCV) does not always mean the red blood cells are actually normal in size.

What’s happening here?

MCV measures the average size of red blood cells (RBCs).

In the image:

  • One side has small cells (microcytes)
  • The other side has large cells (macrocytes)

When you average them together, the result can appear ‘normal’

So the lab value says ‘normal MCV,’ but in reality, there is a mixed population of abnormal cells.

This phenomenon is called:
Anisocytosis: meaning variation in red blood cell sizes.

Why does this matter clinically?

A normal MCV can hide underlying disease, such as:

  • Combined deficiencies:

Iron deficiency – small cells

Vitamin B12 or folate deficiency – large cells

  • Recent blood transfusion (mix of donor and patient cells)
  • Certain bone marrow disorders

How do we detect the ‘different reality’?

We don’t rely on MCV alone. We also look at:

  • Red Cell Distribution Width (RDW)

Measures variation in RBC size
High RDW = mixed population (like in the image)

  • Peripheral blood smear

Directly shows the mix of small and large cells

Key takeaway:

  • A normal average (MCV) can be misleading.
  • Always interpret it alongside RDW and blood smear findings.”

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