Empeiria

Mean corpuscular volume

Also known as MCV, mean cell volume

derived index · no single molecular formula

LOINC 787-2 code verified whole_blood fL

unverified These explanations are written to be easy to read and have not yet been checked against a source. The ranges and measurement notes on this page show theirs.

definition unverified

The average size of your red blood cells. On its own it means little; next to a low haemoglobin it is the single most useful clue to the cause.

The average size of your red blood cells. On its own it means little; next to a low haemoglobin it is the single most useful clue to the cause.

No clinical version written yet.

why measured unverified

If you are anaemic, cell size splits the likely causes into two groups. That is why it is always shown next to the red cell count.

If you are anaemic, cell size splits the likely causes into two groups. That is why it is always shown next to the red cell count.

No clinical version written yet.

if high unverified

Cells are larger than usual. Common reasons are a shortage of vitamin B12 or folate, regular alcohol, some medicines, and an underactive thyroid.

Cells are larger than usual. Common reasons are a shortage of vitamin B12 or folate, regular alcohol, some medicines, and an underactive thyroid.

No clinical version written yet.

if low unverified

Cells are smaller than usual. The common reason is iron shortage. An inherited condition called thalassaemia trait also does this and is harmless.

Cells are smaller than usual. The common reason is iron shortage. An inherited condition called thalassaemia trait also does this and is harmless.

No clinical version written yet.

What this substance is

An arithmetic result, not a substance: the average volume of a red cell, obtained from haematocrit divided by red cell count.
How it is calculated

MCV (fL) = (haematocrit % x 10) / RBC count (10^6/uL)

Derived from hematocrit, rbc_count.

Reference ranges

Checking your own result against this range needs the running application; this is a static copy. Nothing you type anywhere in Empeiria is ever sent to a server.

This open edition shows a range only where a public-domain or openly licensed source states one, and none does for this marker yet. Compare your result with the range printed on your own lab report.

How it is measured

In practice

MCV comes from the same blood sample as a complete blood count, taken from a vein. It is part of that count, not a separate test. The lab machine measures the size of many red blood cells and finds the average. No special preparation is needed.

MCV is reported with the CBC on the same K2 EDTA whole-blood sample. On impedance analysers such as the Coulter DxH 800 it is derived from the RBC size histogram (cells 36-360 fL) rather than calculated from other results, and haematocrit is then calculated from RBC x MCV. Abnormal BUN, glucose or sodium can affect MCV. No special preparation is required.

Where: laboratory

Sources: NHANES 2019-2020 Laboratory Procedure Manual: Complete Blood Count (Coulter DxH 800), CDC/NCHS; RBC indices -- MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine cited · not yet checked by a person

In the lab

calculation

Derived from impedance measurements

Worked out from two other numbers on the same blood count rather than measured on its own.

Haematocrit / RBC count, or measured directly by impedance sizing.

Why labs disagree: MCV is reported after multiplying the histogram average by an analyser calibration constant, and depending on the analyser it is either measured from pulse heights or calculated from hematocrit and RBC count, while optical analysers size cells by light scatter instead. A lab's MCV range therefore reflects its own analyser's method and calibration.

Sources: CDC NHANES 2011-2012 Laboratory Procedure Manual: Complete Blood Count using Coulter HMX; Girard S et al. Breaking Free From MCHC Interferences? French-Speaking Cellular Haematology Group (GFHC) Review of Causes, Rising Trends and Practical Solutions. Int J Lab Hematol 2025 (PMC12426809, open access) cited · not yet checked by a person

What it reports on

Associated symptoms

When high
When low

Conditions this marker features in

When high
  • high Liver damage from alcohol · supportive
    Enlarged red cells (macrocytosis) can help support the diagnosis.
  • high Low vitamin B12 · supportive
    Red cells are larger than normal (adult cut-off 100 fL). About 1 in 4 patients have this masked by iron deficiency or thalassaemia trait.
When low
  • low Anaemia caused by long-term illness · supportive
    Usually normal; sometimes mildly low. A normal MCV helps separate it from iron deficiency, where red cells are small.
  • low Carrier of beta-thalassaemia · supportive
    Small red cells (MCV below 80 fL) are usually how a carrier is first found, often by chance on a routine blood count.
  • low Low iron causing anaemia · supportive
    Red cells get smaller (microcytosis), but thalassaemia and some other anaemias do this too.

Ordered as part of

cbc