What is MCV?
A red blood cell is made in the bone marrow in a series of divisions, and how large it ends up depends on what was available during those divisions. If there is too little iron to make haemoglobin, the cell divides once more before it is full enough, and enters the blood small and pale. If there is too little vitamin B12 or folate to make DNA, the division falters while the cell keeps growing, and it enters the blood too large. MCV, the average volume, therefore tells which of the two is going on. It is an average over cells that already exist, and a red cell lasts about four months. So MCV changes slowly: an iron deficiency only makes the cells smaller once the old, normal cells have been broken down and replaced. For an early sign you look at RDW, the spread in cell size, which rises as soon as the new cells differ from the old. And with a deficiency of iron and B12 at the same time the effects can cancel out, with a normal MCV and a high RDW. Your report shows MCV in fL. Normal is 80 to 100 fL, and that range is the same everywhere. MCV is calculated from haematocrit and the red cell count, and does not move with your fluid balance.
Why is MCV relevant?
MCV is the value that points the way straight away with a low haemoglobin. Small cells: iron, and then ferritin is the next question, plus where the blood is going. Large cells: B12 or folate, and then those two are the next question, plus alcohol and the thyroid. Normal cells with anaemia: blood loss, a chronic inflammation or the kidneys. That three-way split saves a detour, and it sits in every blood count, even when nothing seems wrong yet. For anyone without anaemia, MCV is mainly interesting at the high end. Alcohol is the most common reason for oversized red cells in someone otherwise healthy: it disturbs production in the marrow directly, and an MCV at the top of the band or above it, with a normal B12 and folate, is often the first measurable trace of drinking too much, earlier than the liver values. It falls again in the months after you cut down, and that makes it an honest measure for anyone who wants to know whether the switch has really been flipped. A B12 deficiency from plant-based eating, antacids or metformin also lets MCV rise, often years before haemoglobin falls. At the low end without anaemia, thalassaemia trait is the most common explanation: small cells, a high count, a normal ferritin. That is not a disease and asks for nothing, except that you know it, because it looks like iron deficiency and iron does not help then.
MCV reference ranges
What counts beside the number:
- Haemoglobin, because MCV points the way as soon as there is anaemia
- RDW, the spread in cell size, which shows a change earlier than the average
- Ferritin with small cells: low in iron deficiency, normal in thalassaemia
- Vitamin B12, folate and TSH with large cells
- How much you drink, because alcohol is the most common explanation for large cells
- The trend over months, because a red cell lasts four months
MCV is one of the few values the labs agree on exactly, so for MCV the question is not where the limit sits but what causes a deviation. It is an average over cells that last four months, so it changes slowly; RDW shows earlier that something is shifting. With a deficiency of iron and B12 at the same time the MCV can be normal while both are at play.
MCV = haematocrit divided by the red cell count
fL
÷ × 1000 =
What Dutch labs actually use
80 – 100fL
Outside this range every lab calls it abnormal.
every lab calls 80 – 100 fL normal. Outside that range every lab calls it abnormal.
Every age, per lab
| Laboratory | Group | Reference range |
|---|---|---|
| Unilabs(Saltro, Medlon, SHO, Atalmedial)2026 | Men from 16 yrs | 80–100 fL |
| Women from 16 yrs | 80–100 fL | |
| Star-shl2026 | 19+ | 80–100 fL |
| Certe2026 | Men from 18 yrs | 80–100 fL |
| Women from 18 yrs | 80–100 fL | |
| Clinical Diagnostics2026 | From 16 yrs | 80–100 fL |
Each band as the lab publishes it, retrieved in 2026, unless marked otherwise.
MCV high or low: what it means
A low MCV means small cells. The most common explanation first: an iron deficiency, thalassaemia trait, and rarely a chronic disease. Ferritin tells the difference: low in iron deficiency, normal in thalassaemia. In an iron deficiency the MCV is only low once the deficiency has existed for months; the symptoms and the ferritin come before it. A high MCV means large cells. In order: a deficiency of vitamin B12 or folate, alcohol, an underactive thyroid, medicines such as methotrexate and some drugs against epilepsy and HIV, and rarely a bone marrow problem. B12 and folate you settle with a draw, alcohol you settle yourself, and the thyroid with TSH. A high MCV with a normal B12 and folate is nine times out of ten alcohol. What you do about it: with small cells you top up iron and see the MCV rise in the months after; with large cells you top up B12 or folate, or cut down on alcohol, and the MCV falls in the months after. Count on three to four months, the lifespan of a red cell, before the value shows the new balance. Read MCV beside haemoglobin, MCH, MCHC and RDW, and beyond that beside ferritin with a low value and B12, folate and TSH with a high one. Compare over time, because the trend says more than one number.
What lowers it
Cells that stay small because there was too little iron to fill them.
| Cause | How often |
|---|---|
| Iron deficiencyWithout enough iron the cell divides once more before it is full; the MCV only falls once the deficiency has existed for months, and ferritin is then low | Often |
| Thalassaemia traitAn inherited feature with small cells, a high count and a normal ferritin; not a disease, but good to know because iron does not help then | Sometimes |
| Chronic diseaseA long-standing inflammation holds on to iron; the cells sometimes become somewhat smaller, usually they stay normal | Rare |
What raises it
Cells that become too large because the division falters while the cell keeps growing.
| Cause | How often |
|---|---|
| Vitamin B12 or folate deficiencyWithout B12 or folate the marrow cannot make DNA; the division falters and the cells enter the blood too large, often years before haemoglobin falls | Often |
| AlcoholDisturbs production in the marrow directly; with a normal B12 and folate the most common reason, and the first measurable trace of drinking too much | Often |
| Thyroid problemsAn underactive thyroid slows production and makes the cells somewhat larger; TSH shows it | Sometimes |
| MedicationMethotrexate, some drugs against epilepsy and HIV, and chemotherapy disturb the division in the marrow | Sometimes |
| Bone marrow problemA marrow that itself makes abnormal cells; rare, and then the white cells and platelets are usually abnormal too | Rare |
How does a MCV blood test work?
- Referral
- Not needed. MCV is in every blood count you can have measured yourself.
- Fasting
- Not needed. MCV does not move with food or with your fluid balance.
- When
- At any time; the value changes over months, not over days.
- The draw
- One tube of blood from a vein in your arm, the same tube as for the rest of your blood count; MCV is calculated from haematocrit and the red cell count.
- Which test
- MCV is in the Iron & fatigue test (€99) and in .
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
What is MCV?
The average volume of your red blood cells, in femtolitres. It says whether your cells are on average small, normal or large, and in anaemia that is the first fork: small cells point at iron, large ones at B12, folate or alcohol. Because a red cell lasts four months, MCV changes slowly and describes the past months.
What is a normal MCV level?
80 to 100 fL, for men and women and at every adult age, and here the labs agree exactly. So for MCV the question is not where the limit sits, but what causes a deviation, and where you sit within the band also says something over time: an MCV slowly rising is often alcohol or an early B12 deficiency.
What does a low MCV mean?
Small cells. Usually an iron deficiency that has existed for months: without enough iron the cell divides once more before it is full. The other explanation is thalassaemia trait, an inherited feature with small cells and a normal ferritin, which is not a disease but looks like iron deficiency. Ferritin tells the two apart, and that saves taking iron that does not help.
What does a high MCV mean?
Large cells. A deficiency of vitamin B12 or folate lets the division in the marrow falter while the cell keeps growing, and alcohol does the same directly. After that come an underactive thyroid and medicines such as methotrexate and some drugs against epilepsy. With a normal B12 and folate a high MCV is nine times out of ten alcohol, and it falls in the months after you cut down.
What does alcohol have to do with MCV?
Alcohol disturbs the production of red cells in the marrow, and oversized cells are therefore often the first measurable trace of drinking too much, earlier than the liver values. An MCV at the top of the band or above it, with a normal B12 and folate, is an honest measure. If you cut down, the MCV falls with it in three to four months, the time the marrow needs to replace the old cells.
Why does MCV change so slowly?
Because it is an average over all the red cells there are, and those last about four months. A deficiency only makes the new cells different; the average shifts only once the old ones have been broken down. That is why RDW, the spread in cell size, shows a change earlier: it rises as soon as the new cells deviate from the old. So repeat MCV only after three to four months.
Can MCV be normal while something is still going on?
Yes. With a deficiency of iron and B12 or folate at the same time, the small and the large cells together make a normal average, while RDW is high because the spread is wide. And in the first months of a deficiency the MCV is still normal because the old cells are still there. Ferritin, B12 and RDW then say more than the MCV.
Do I need to fast for an MCV test?
No. MCV does not move with food or with your fluid balance, and it comes from the same tube as your whole blood count, so haemoglobin, RDW and the red cell count sit beside it automatically.
Which tests include MCV?
MCV is in the Iron & fatigue test (€99, also as an add-on for €15), in the Biological age test (€69, also as an add-on for €15), in the comprehensive test (€229) and in .
Related biomarkers
Read on
Sources
- 1.NHG guideline on anaemia (M76), Dutch College of General Practitioners. 2024. richtlijnen.nhg.org
- 2.Unilabs, test catalogue (Dutch): MCV. 2026. bepalingenklapper.nl
- 3.Star-shl, test catalogue (Dutch): MCV. 2026. star-shl.nl
- 4.Certe, test catalogue (Dutch): MCV. 2026. bepalingenwijzer.certe.nl
- 5.Clinical Diagnostics, lab guide (Dutch): MCV. 2026. clinicaldiagnostics.nl
- 6.LESA Laboratory diagnostics (Dutch primary-care laboratory agreement). 2026. richtlijnen.nhg.org
Educational information only, not medical advice. Consult a healthcare professional for clinical decisions.
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