MCV and MCH Levels Explained: Your Red Cell Results

When you have a full blood count, the report includes a set of results called the red cell indices. MCV, MCH, MCHC and RDW describe the size of your red blood cells, how much haemoglobin each one carries and how much they vary. They are often the first clue to why someone is anaemic.

This guide explains what each of these four results means, typical ranges, what a low or high result can point to, and which follow-up tests usually find the cause. For the rest of the report, see what a full blood count shows.

Test it in Chiswick: our Full Blood Count blood test costs £59, with your result explained in person by a practitioner. No GP referral needed. Book this test or call 020 4515 0000.

Quick answer

MCV (mean cell volume) is the average size of your red blood cells, and MCH (mean cell haemoglobin) is the average amount of haemoglobin in each cell. Typical adult ranges at NHS laboratories are about 80 to 100 fL for MCV and 27 to 32 pg for MCH, though ranges vary. A low MCV most often points to iron deficiency or thalassaemia trait. A high MCV is commonly linked to alcohol, liver disease, thyroid problems, vitamin B12 or folate deficiency, or some medicines. Tests such as ferritin, B12 and folate usually find the cause.

The red cell indices at a glance

Ranges below come from NHS laboratories and differ slightly between them, so always use the range on your report.

• MCV (mean cell volume): the average size of a red cell, measured in femtolitres (fL). Typical range about 80 to 100 fL, with some laboratories using 83 to 100 fL.
• MCH (mean cell haemoglobin): the average weight of haemoglobin in each red cell, in picograms (pg). Typical range about 27 to 32 pg.
• MCHC (mean cell haemoglobin concentration): how concentrated the haemoglobin is inside the cells. One NHS laboratory uses 310 to 350 g/L, and some report it in g/dL instead.
• RDW (red cell distribution width): how much your red cells vary in size, as a percentage. One NHS laboratory uses 11 to 16%.

Our Full Blood Count reports MCV, MCH and MCHC. If you would like RDW as well, our Full Blood Count with RDW costs £69.

What your result means

• Low MCV (below about 80 fL), often with a low MCH: small red cells, called microcytosis. Iron deficiency and thalassaemia trait are the most common reasons.
• MCV within range: red cells are a normal size. If haemoglobin is also normal, this is reassuring.
• High MCV (above about 100 fL): large red cells, called macrocytosis. Causes range from alcohol and medicines to vitamin B12 or folate deficiency.
• Normal MCV with low haemoglobin: normocytic anaemia, which needs a different set of checks (see below).

Low MCV and MCH: small red cells

NHS haematology guidance lists the main causes of a low MCV as:

• Iron deficiency: the NHS says heavy periods and pregnancy are very common causes, and bleeding from the stomach or bowel is another, for example from anti-inflammatory painkillers, ulcers or, less often, bowel or stomach cancer.
• Thalassaemia trait: an inherited difference in haemoglobin that is usually harmless but matters for family planning.
• Anaemia of chronic disease: linked to long-term inflammation or infection.
• Rare causes: such as lead poisoning or inherited sideroblastic anaemia.

The other indices give clues. With thalassaemia trait, the MCV and MCH are often lower than the haemoglobin level would suggest, the red cell count is high and RDW is normal. With iron deficiency, RDW is usually raised and the red cell count is low or normal. Ferritin is the first test to check iron stores. Because inflammation can push ferritin up into the normal range, a CRP test is sometimes added. NHS guidance also notes that alpha thalassaemia trait is not picked up by a standard haemoglobinopathy screen. Read more in our ferritin levels guide.

High MCV: large red cells

NHS haematology guidance lists these causes of a raised MCV:

• alcohol and liver disease
• medicines, especially methotrexate, hydroxycarbamide, chemotherapy and other drugs that affect the immune system
• thyroid problems
• vitamin B12 or folate deficiency
• the body making lots of new red cells after blood loss or red cell breakdown (haemolysis)
• pregnancy
• less commonly, bone marrow conditions, which often also lower white cells or platelets
• a delay before the sample is analysed

The NHS explains that pernicious anaemia, where the immune system stops the stomach absorbing B12, is the most common cause of B12 deficiency in the UK. A vegan diet without B12 supplements or fortified foods, and some medicines such as proton pump inhibitors and anticonvulsants, can also play a part. Suggested next tests include liver function, B12, folate and thyroid function. See our guides to vitamin B12 levels and folate levels.

Normal MCV with anaemia

When haemoglobin is low but red cells are a normal size, NHS guidance says the main cause is anaemia of chronic disorders, linked to long-term infection or inflammation. Iron, B12 and folate can still be low with a normal MCV, so the usual next tests are ferritin, B12, folate, kidney and liver tests, CRP and thyroid function. Our guide to haemoglobin levels explains the numbers, and blood tests for anaemia covers the types of anaemia.

Which follow-up tests help?

• Ferritin (£49) or our Iron Status Check (£59) for iron stores
• Vitamin B12 (£49) and Folate (£49) for a high MCV
• TSH (£39) to check thyroid function
• Liver Function Check (£49) if alcohol or liver disease is possible
• Our Anaemia Check (£129), which combines a full blood count with iron studies, B12, folate and CRP

Symptoms to look out for

The NHS lists tiredness, shortness of breath, palpitations, pale skin and headaches as common symptoms of iron deficiency anaemia. Vitamin B12 or folate deficiency can also cause pins and needles, a sore red tongue, mouth ulcers, muscle weakness, problems with vision or memory, and low mood. Many people with an abnormal MCV have no symptoms at all.

When to see your GP or get urgent help

• See your GP if you have symptoms of anaemia, a result outside the range, or iron deficiency without an obvious reason such as heavy periods. The NHS advises that B12 or folate deficiency should be diagnosed and treated as soon as possible, as some nerve problems can become permanent.
• Contact NHS 111 if you are more short of breath than usual or have palpitations.
• Call 999 or go to A&E if you have severe difficulty breathing, your chest feels tight or heavy, or pain spreads to your arms, back, neck or jaw. Also call 999 if you vomit blood and feel unwell, faint or confused, or have black poo.

Preparing for your test

You do not need to fast for a full blood count. Tell us about any medicines, iron or vitamin supplements, alcohol intake and whether you are pregnant, as these all affect how the indices are read. Children have their own reference ranges.

How often to retest

After treatment for iron, B12 or folate deficiency, your GP will usually repeat the blood count to check it is working. For a raised MCV with no anaemia and no cause found, NHS guidance suggests monitoring every 6 to 12 months.

Frequently asked questions

Is an MCV of 102 high?

Yes, it is just above most laboratory ranges. Common reasons include alcohol, medicines, thyroid problems and low B12 or folate. Your practitioner or GP will look at the rest of your blood count and suggest follow-up tests.

What does a low MCH mean?

Each red cell is carrying less haemoglobin than usual. It usually goes with a low MCV and most often reflects iron deficiency or thalassaemia trait.

Can you have a low MCV without anaemia?

Yes. With thalassaemia trait, the MCV is often lower than the haemoglobin level would suggest, and the trait itself is usually harmless and causes no symptoms. A practitioner can explain whether further tests make sense.

Does alcohol raise MCV?

It can. NHS guidance lists alcohol and liver disease among the main causes of a raised MCV. A raised MCV together with a raised GGT can point towards alcohol.

What is RDW on a blood test?

RDW shows how much your red cells vary in size. A raised RDW is common in iron deficiency, while thalassaemia trait usually has a normal RDW, which helps tell the two apart.

Full blood count testing in Chiswick

We take your blood sample at our clinic at 8 to 9 Bedford Corner, The Avenue, Chiswick, London W4 1LZ, a short walk from Turnham Green station on the District line (Piccadilly line trains stop there early morning and late evening only), and on the 94, E3 and 272 bus routes. Limited parking is available on request when you book. Your sample is analysed at the Randox accredited laboratory, most results are back within a few working days, and a practitioner talks you through what your result means. No GP referral is needed, and we can send a GP feedback report on request.

Book our Full Blood Count, or choose the Anaemia Check to look for the cause in one visit. You can also compare every blood test and price, read our haemoglobin levels guide, or see our guide to the white blood cell count for the rest of your report.

This article is general information, not medical advice. Discuss your results with your GP or practitioner.