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MCV levels: what do they tell you about your health?
MCV stands for mean corpuscular volume — the average volume of your red blood cells. It is a standard component of the complete blood count and provides information about the size of your erythrocytes. Red blood cells that are too large or too small can indicate a deficiency in certain nutrients, a blood disorder, or an underlying disease. MCV is rarely assessed in isolation — it is most valuable in combination with other blood values such as haemoglobin, MCH, and ferritin.
Reference Ranges
Low
80
Normal
100
High
Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.
What It Measures
The MCV test measures the average volume of your red blood cells, expressed in femtolitres (fL). It is calculated as part of a complete blood count by dividing the total volume of red blood cells by their number.
A normal MCV falls between 80 and 100 fL. Blood cells with a volume below 80 fL are called microcytic (too small), while those above 100 fL are macrocytic (too large). Both abnormalities point towards the possible cause of anaemia or other blood disorders.
MCV is almost always interpreted alongside other parameters: MCH (the amount of haemoglobin per cell), MCHC (the concentration of haemoglobin per cell), and the haemoglobin level itself. Together, they tell a more complete story about your oxygen transport and nutritional status.
A normal MCV falls between 80 and 100 fL. Blood cells with a volume below 80 fL are called microcytic (too small), while those above 100 fL are macrocytic (too large). Both abnormalities point towards the possible cause of anaemia or other blood disorders.
MCV is almost always interpreted alongside other parameters: MCH (the amount of haemoglobin per cell), MCHC (the concentration of haemoglobin per cell), and the haemoglobin level itself. Together, they tell a more complete story about your oxygen transport and nutritional status.
Why It Matters
Your MCV value helps identify the cause of anaemia. When haemoglobin is low, MCV is often the first clue: is the problem an iron deficiency (low MCV), a vitamin B12 or folate deficiency (high MCV), or something else?
A decreased MCV (microcytosis) most commonly points to iron deficiency, one of the most prevalent nutritional deficiencies worldwide. It is particularly common in women with heavy menstrual bleeding, in vegetarians, and in people with chronic gastrointestinal bleeding.
An increased MCV (macrocytosis) is an important signal for a vitamin B12 or folate deficiency. In the elderly, vegans, and people with gastrointestinal conditions (such as coeliac disease or Crohn's disease), this is relatively common. Excessive alcohol consumption is another frequent cause of high MCV — it has a direct toxic effect on red blood cell formation.
Additionally, an abnormal MCV can indicate hereditary conditions such as thalassaemia (low MCV) or thyroid problems (high MCV in hypothyroidism).
A decreased MCV (microcytosis) most commonly points to iron deficiency, one of the most prevalent nutritional deficiencies worldwide. It is particularly common in women with heavy menstrual bleeding, in vegetarians, and in people with chronic gastrointestinal bleeding.
An increased MCV (macrocytosis) is an important signal for a vitamin B12 or folate deficiency. In the elderly, vegans, and people with gastrointestinal conditions (such as coeliac disease or Crohn's disease), this is relatively common. Excessive alcohol consumption is another frequent cause of high MCV — it has a direct toxic effect on red blood cell formation.
Additionally, an abnormal MCV can indicate hereditary conditions such as thalassaemia (low MCV) or thyroid problems (high MCV in hypothyroidism).
When to Test
MCV is a standard component of a complete blood count, so it is often measured automatically. It is particularly useful when symptoms consistent with anaemia are present: fatigue, pallor, dizziness, shortness of breath, or difficulty concentrating.
If you already know you have anaemia, MCV helps identify the cause and guide appropriate treatment. With a known deficiency in iron, vitamin B12, or folate, repeated MCV measurements can show whether supplementation is having an effect.
MCV is also regularly measured in cases of prolonged excessive alcohol use, as it is one of the most sensitive markers for alcohol-related liver damage. Fasting is not required for MCV.
If you already know you have anaemia, MCV helps identify the cause and guide appropriate treatment. With a known deficiency in iron, vitamin B12, or folate, repeated MCV measurements can show whether supplementation is having an effect.
MCV is also regularly measured in cases of prolonged excessive alcohol use, as it is one of the most sensitive markers for alcohol-related liver damage. Fasting is not required for MCV.
Symptoms
Low Levels
A decreased MCV (below 80 fL) means your red blood cells are smaller than normal. This is called microcytosis and is often the result of iron deficiency. Symptoms may include fatigue, pallor, cold hands and feet, irritability, brittle nails, and hair loss. In women with heavy menstrual bleeding, low MCV is a common finding.
High Levels
An elevated MCV (above 100 fL) indicates macrocytosis — your red blood cells are larger than normal. Symptoms partially overlap with those of low MCV: fatigue, pallor, and shortness of breath. With a vitamin B12 deficiency, neurological symptoms may also occur, such as tingling in hands and feet, balance problems, and memory issues.
In alcohol-related macrocytosis, there are often no symptoms directly linked to the MCV — the elevation is a signal of liver or bone marrow damage.
An MCV above 110 fL is significantly elevated and warrants further investigation for vitamin B12 deficiency, folate deficiency, thyroid problems, or a bone marrow disorder.
In alcohol-related macrocytosis, there are often no symptoms directly linked to the MCV — the elevation is a signal of liver or bone marrow damage.
An MCV above 110 fL is significantly elevated and warrants further investigation for vitamin B12 deficiency, folate deficiency, thyroid problems, or a bone marrow disorder.
Lifestyle Tips
For low MCV due to iron deficiency, diet is an important factor. Iron-rich foods — red meat, legumes, dark leafy greens, and whole grains — help replenish your iron stores. Combine plant-based iron with vitamin C (bell peppers, citrus fruits) for better absorption. Tea and coffee with meals actually inhibit iron absorption.
For high MCV due to vitamin B12 deficiency, consider more animal products (meat, fish, eggs, dairy) or targeted supplementation. Vegans always need a B12 supplement. Folate is found particularly in green leafy vegetables, legumes, and citrus fruits.
If alcohol use is the cause of high MCV, reducing or stopping is the only effective measure. MCV typically normalises within two to four months after cessation.
For high MCV due to vitamin B12 deficiency, consider more animal products (meat, fish, eggs, dairy) or targeted supplementation. Vegans always need a B12 supplement. Folate is found particularly in green leafy vegetables, legumes, and citrus fruits.
If alcohol use is the cause of high MCV, reducing or stopping is the only effective measure. MCV typically normalises within two to four months after cessation.
Frequently Asked Questions
What is a normal MCV level?
A normal MCV falls between 80 and 100 femtolitres (fL). Values below 80 fL indicate microcytosis (red blood cells that are too small), while values above 100 fL indicate macrocytosis (red blood cells that are too large). Normal values are virtually identical for men and women.
What does a low MCV mean?
A low MCV (below 80 fL) means your red blood cells are smaller than normal. The most common cause is iron deficiency. Other possible causes include thalassaemia (an inherited blood disorder) and chronic diseases.
What does a high MCV mean?
A high MCV (above 100 fL) indicates larger red blood cells than normal. This can be caused by a vitamin B12 or folate deficiency, excessive alcohol consumption, thyroid problems, or certain medications.
Do I need to fast before an MCV test?
No, fasting is not required for an MCV test. MCV is part of the standard blood count and is not affected by food intake.
Can alcohol affect my MCV?
Yes, excessive alcohol use is one of the most common causes of elevated MCV. Alcohol has a direct toxic effect on red blood cell production in the bone marrow. After stopping drinking, MCV usually normalises within two to four months.
Is MCV tested separately or as part of a blood count?
MCV is almost always measured as part of a complete blood count (CBC), alongside haemoglobin, haematocrit, MCH, MCHC, and other parameters. It is rarely requested as a standalone test.