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Anemia

MCV

MCV is the average size of your red blood cells and helps distinguish the type of anemia.

What is MCV?

MCV measures the average size of your red blood cells. Small cells (low MCV) often point to iron deficiency or thalassaemia trait. Large cells (high MCV) fit B12 or folate deficiency, heavy alcohol use, or a thyroid problem. With normal cell size but still anaemia, think chronic disease or kidney function loss. MCV changes slowly — shifts take weeks to months to become visible. One caveat: with simultaneous iron and B12 deficiency, both effects cancel each other out and produce a falsely normal MCV. RDW then reveals the underlying variation.

Why is MCV relevant?

MCV is the fastest first pointer in anaemia assessment. A low value directs you to iron markers; a high value to B12, folate, and thyroid function. Without MCV you would need to order follow-up tests blindly. For people testing preventively, MCV helps catch early iron deficiency or a developing B12 problem, sometimes before haemoglobin has fallen.

MCV high or low — what it means

Read MCV alongside RDW, haemoglobin, MCH, and MCHC. Add ferritin with low MCV, and B12 plus folate with high MCV. Elevated RDW with low MCV fits iron deficiency; normal RDW with low MCV more often fits thalassaemia trait. Trends across multiple measurements say more than one reading — a gradually falling MCV in someone who has stopped iron supplementation tells a clearer story than a single abnormal result.

MCV reference ranges

Normal (adults)Microcytic below 80 fL (often iron deficiency), macrocytic above 100 fL (often B12 or folate deficiency).80-100 fL

Cut-offs vary slightly by lab and method; always read MCV alongside RDW, haemoglobin, MCH and MCHC.

Educational information only — not medical advice. Consult a healthcare professional for clinical decisions.

Read about our scientific approach →Read the guide: Energy →

Frequently asked questions

What is a normal MCV value?

In healthy adults MCV usually falls between 80 and 100 femtolitres (fL). The exact bounds vary a little by laboratory, so always compare your result with the reference range on your own lab report. There is no clinically relevant difference between men and women.

What does a high MCV value mean?

An MCV above roughly 100 fL (macrocytic) means your red blood cells are on average larger than normal. This classically fits a vitamin B12 or folate deficiency, but can also accompany heavy alcohol use or an underactive thyroid. Follow-up testing focuses on B12, folate and thyroid function.

What does a low MCV value mean?

An MCV below roughly 80 fL (microcytic) means your red blood cells are on average smaller than normal. The most common cause is iron deficiency; with a normal RDW it can also point to thalassaemia trait. A low MCV is usually a reason to check ferritin and your iron status.

When is an abnormal MCV value concerning?

A mildly abnormal MCV with no symptoms and an otherwise normal blood count is rarely immediately concerning; a repeat gives more certainty. MCV changes slowly (weeks to months). An abnormal MCV together with anaemia (low haemoglobin), fitting symptoms, or a mixed picture (e.g. raised RDW) does warrant follow-up with a clinician.

Related biomarkers

MCH
MCH is the average amount of hemoglobin contained in each red blood cell.
MCHC
MCHC shows how concentrated the hemoglobin inside your red blood cells is.
RDW
RDW shows how much your red blood cells vary in size from one another.
Erythrocytes (RBC Count)
Erythrocytes are your red blood cells, and the RBC count measures them per volume of blood to gauge oxygen transport.

MCV is one of the biomarkers in the Optimize blood test. Book a blood draw at any of 238+ partner labs in the Netherlands, or upload your existing results in the app.

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