Full blood count (FBC / CBC)
MCV blood test: what a high or low result means
What MCV (mean cell volume) on a blood test means, why red cells can be small or large, and what to ask your doctor.
Got your MCV result in front of you?
Paste your whole results sheet (or upload a photo, PDF or Word file) and Patiently AI explains it in plain English, sticking to the numbers and ranges on your report. Free, no account, and identifying details are removed on your device first.
Explain my results → Available on web, iOS & Android.What is MCV?
MCV stands for mean cell volume, also called mean corpuscular volume. It is the average size of your red blood cells, and it is reported as part of a full blood count (FBC, or CBC in the US). MCV is especially useful when your haemoglobin is low, because the size of the red cells points towards the likely cause of anaemia.
Why is this test done?
- To help work out the cause of anaemia
- As part of a routine full blood count
- To monitor alcohol-related or nutritional problems
- To follow up a previous abnormal result
What does a high MCV mean?
A high MCV means your red cells are larger than usual. This is called macrocytosis.
Possible reasons include:
- Low vitamin B12 or folate
- Regular heavy alcohol use
- Liver disease
- An underactive thyroid
- Some medicines, such as methotrexate and some HIV and anti-seizure medicines
- Less commonly, a bone marrow condition
What does a low MCV mean?
A low MCV means your red cells are smaller than usual. This is called microcytosis.
Possible reasons include:
- Iron deficiency, the most common cause
- Inherited conditions that affect haemoglobin, such as thalassaemia trait
- Long-term inflammation or illness
Why we don't list a "normal range". Reference ranges differ between laboratories and can depend on your age, sex and whether you are pregnant. The range printed next to your result on your own report is the one that applies to you, so use that, and talk to your doctor about what your result means for you.
What can affect your MCV result?
- Pregnancy, which can raise MCV slightly
- A recent blood transfusion
- Very recent bleeding, when the body makes new, larger cells
- Having both iron deficiency and low B12, which can make MCV look normal
Make sense of the whole report, not just one line
Results are easier to understand together. Patiently AI explains your report as a whole and writes personalised questions for your next appointment.
Try it with your own results → Paste, upload or photograph your results.Questions to ask your doctor
- What does my MCV suggest about the cause of my result?
- Do I need iron, vitamin B12 or folate tests?
- Could alcohol, my thyroid or a medicine be affecting it?
- Should I be tested for an inherited condition such as thalassaemia trait?
Frequently asked questions
Is a high MCV serious?
Usually it points to something that can be checked and treated, such as low vitamin B12 or folate, alcohol or a medicine. Your doctor will usually arrange further tests to find the cause.
Can I have a normal MCV and still be anaemic?
Yes. Some types of anaemia have normal-sized red cells, and a mix of causes can cancel each other out. MCV is one clue among several.
What are MCH and MCHC?
They are related measurements on a full blood count. MCH is the average amount of haemoglobin in each red cell, and MCHC is the concentration of haemoglobin in the red cells. They usually move in the same direction as MCV.
Can Patiently AI explain my MCV result?
Yes. Paste your results, or upload a photo, PDF or Word file, and Patiently AI explains them in plain English, sticking to the numbers and ranges on your own report rather than adding its own, and suggests questions to ask your doctor. It is free, needs no account, and removes identifying details on your device first.