MCV Blood Test? Why Your Blood Cells Are Changing & Medically Approved Next Steps

If you've recently had blood work done, you may have noticed a result called MCV. Seeing numbers outside the "normal range" can be confusing. What does it mean? Should you worry?

This guide explains the MCV blood test in clear, practical terms — what it measures, why it changes, and what medically approved next steps may look like.

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What Is an MCV Blood Test?

MCV stands for Mean Corpuscular Volume. It measures the average size of your red blood cells.

Red blood cells carry oxygen from your lungs to the rest of your body. Their size matters because it can reveal important information about your overall health.

The MCV blood test is typically part of a Complete Blood Count (CBC) — a routine test your doctor may order during:

• Annual physical exams
• Evaluation of fatigue or weakness
• Investigation of anemia
• Monitoring of chronic conditions

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What Is a Normal MCV Level?

For most adults, a normal MCV range is:

80 to 100 femtoliters (fL)

• Below 80 fL = Red blood cells are smaller than normal
• Above 100 fL = Red blood cells are larger than normal

Keep in mind: "Normal" ranges can vary slightly between laboratories.

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Why Do Red Blood Cells Change Size?

Changes in red blood cell size usually relate to how your body is producing them. Red blood cells are made in your bone marrow and require specific nutrients — especially iron, vitamin B12, and folate.

When something interferes with that process, cell size can change.

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Low MCV (Microcytosis): What It Means

If your MCV blood test result is low, your red blood cells are smaller than normal.

Common Causes of Low MCV

• Iron deficiency anemia (most common cause)
• Chronic blood loss (heavy periods, stomach ulcers, colon bleeding)
• Thalassemia (a genetic blood disorder)
• Chronic inflammatory conditions

Symptoms You Might Notice

Some people have no symptoms at first. Others may experience:

• Fatigue
• Pale skin
• Shortness of breath
• Dizziness
• Brittle nails

Iron deficiency is especially common in:

• Women with heavy menstrual periods
• Pregnant individuals
• People with digestive disorders (like celiac disease)
• Those who follow restrictive diets

If you're experiencing these symptoms and want to understand whether they could be related to Anemia, a free AI-powered symptom checker can help you prepare for your doctor's appointment with organized information about what you're feeling.

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High MCV (Macrocytosis): What It Means

If your MCV blood test result is high, your red blood cells are larger than normal.

Common Causes of High MCV

• Vitamin B12 deficiency
• Folate deficiency
• Alcohol use
• Liver disease
• Hypothyroidism
• Certain medications
• Bone marrow disorders (less common but serious)

Symptoms May Include

• Fatigue
• Weakness
• Numbness or tingling (especially with B12 deficiency)
• Memory issues
• Pale or slightly yellowish skin

Vitamin B12 deficiency is particularly important because untreated cases can cause nerve damage. This is why it's important not to ignore a high MCV result.

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Can MCV Be Abnormal Without Anemia?

Yes.

An abnormal MCV blood test does not automatically mean you have anemia. Sometimes:

• The change is mild
• Other blood counts are normal
• The issue is temporary (e.g., after illness)

Doctors look at MCV alongside other CBC values, including:

• Hemoglobin
• Hematocrit
• Red blood cell count (RBC)
• RDW (Red Cell Distribution Width)

MCV is just one piece of the puzzle.

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What Causes Iron Deficiency?

Because iron deficiency is the most common reason for low MCV, it's worth understanding why it happens.

Common Causes

• Heavy menstrual bleeding
• Pregnancy
• Gastrointestinal bleeding
• Poor dietary intake
• Malabsorption (e.g., celiac disease, gastric surgery)

In adults — especially men and postmenopausal women — iron deficiency may signal internal bleeding, often from the gastrointestinal tract. That's why doctors may recommend further evaluation.

This is not meant to alarm you, but it is important to investigate the cause rather than just taking supplements without medical guidance.

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What Causes Vitamin B12 or Folate Deficiency?

High MCV is often linked to vitamin deficiencies.

Vitamin B12 Deficiency Can Be Caused By:

• Pernicious anemia (autoimmune condition)
• Long-term vegetarian or vegan diet without supplementation
• Stomach surgery
• Chronic gastritis
• Certain medications (like long-term metformin use)

Folate Deficiency May Be Caused By:

• Poor diet
• Alcohol use
• Pregnancy
• Malabsorption conditions

Unlike iron deficiency, B12 deficiency can cause neurological symptoms, which makes early detection important.

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What Happens Next If Your MCV Is Abnormal?

Your doctor will likely:

1. Review your full CBC results
2. Ask about symptoms
3. Review medications and alcohol use
4. Order additional blood tests if needed

These tests may include:

• Iron studies (ferritin, transferrin saturation)
• Vitamin B12 level
• Folate level
• Thyroid function tests
• Liver function tests

If blood loss is suspected, further testing such as stool studies or imaging may be recommended.

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Should You Be Worried?

An abnormal MCV blood test result deserves attention — but not panic.

In many cases, the cause is:

• Nutritional deficiency
• Mild iron depletion
• A treatable underlying condition

However, ignoring abnormal results is not wise. Persistent anemia or untreated vitamin deficiencies can lead to complications.

If you experience any of the following, seek medical care promptly:

• Chest pain
• Severe shortness of breath
• Fainting
• Rapid heartbeat
• Confusion
• Numbness or balance problems

These may signal more serious issues.

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Can You Fix MCV Levels Naturally?

Treatment depends entirely on the cause.

For Iron Deficiency:

• Iron supplements (as prescribed)
• Iron-rich foods (red meat, beans, spinach)
• Treating the source of bleeding

For Vitamin B12 Deficiency:

• Oral supplements
• B12 injections (in some cases)
• Dietary changes

For Folate Deficiency:

• Folic acid supplements
• Leafy greens, beans, fortified grains

Do not start high-dose supplements without speaking to your doctor. Too much iron or masking B12 deficiency with folate can create other problems.

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Key Takeaways About the MCV Blood Test

• The MCV blood test measures the average size of your red blood cells.
• Low MCV usually points to iron deficiency or genetic conditions.
• High MCV often relates to vitamin B12 or folate deficiency.
• It's one part of a larger blood panel.
• Most causes are treatable once identified.

If you're experiencing symptoms like fatigue, weakness, pale skin, or numbness, you can use a free Anemia symptom checker to help identify patterns in your symptoms and prepare meaningful questions for your healthcare provider.

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When to Speak to a Doctor

You should speak to a doctor if:

• Your MCV is outside the normal range
• You have symptoms of anemia
• You have neurological symptoms
• You have unexplained fatigue
• You notice blood in stool or very heavy periods

Some causes of abnormal MCV can be serious or even life-threatening if left untreated. That's why professional medical evaluation is essential.

This article provides education — not a diagnosis.

If something feels off, or if your test results are unclear, schedule an appointment and review them with a healthcare professional. Early evaluation leads to better outcomes.

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Understanding your MCV blood test result is the first step. The next step — and the most important one — is making sure you and your doctor work together to find the cause and treat it appropriately.