MCV stands for mean corpuscular volume and it measures the average size of your red blood cells. Think of red blood cells as delivery trucks carrying oxygen. If the trucks are too small or too large, they may not deliver oxygen efficiently.
- Normal MCV range: 80-100 femtoliters (fL)
- High MCV (macrocytosis): Red blood cells are larger than normal
- Low MCV (microcytosis): Red blood cells are smaller than normal
The role of MCV in your overall blood health
When you visit your doctor for a routine checkup, chances are you’ve had a complete blood count (CBC) test. This common blood test measures different components of your blood, including red blood cells, white blood cells, hemoglobin and platelets. One important part of the CBC is mean corpuscular volume (MCV), which tells doctors the average size of your red blood cells. Abnormal MCV levels may point to conditions like anemia, vitamin deficiencies or liver disease. In fact, anemia affects about 9.3% of people in the U.S., and it’s more common in women (13%) than men (5.5%)?
What do high or low MCV levels mean?
Your MCV result gives your healthcare provider clues about the size of your red blood cells—and that size matters because it can signal underlying health issues.
High MCV (macrocytosis): Red blood cells are larger than normal. This often points to problems with how your body makes healthy red blood cells. Common causes include:
- Vitamin B12 or folate deficiency – These nutrients are essential for red blood cell production. Low levels can lead to anemia and nerve issues
- Liver disease – Liver problems can affect how blood cells develop and break down
- Excessive alcohol consumption – Heavy alcohol use can interfere with nutrient absorption and bone marrow function
Low MCV (microcytosis): Red blood cells are smaller than normal. This usually means your body isn’t getting or using enough iron. Common causes include:
- Iron-deficiency anemia – The most common cause of low MCV, often linked to poor diet, blood loss or chronic illness
- Thalassemia – A genetic condition that affects hemoglobin production
- Chronic disease – Long-term health conditions can disrupt iron metabolism and red blood cell formation
Why does this matter?
When red blood cells are too big or too small, they can’t carry oxygen efficiently. Over time, this can lead to fatigue, weakness and other symptoms. Identifying the cause early helps prevent complications and guides treatment—whether that’s improving nutrition, managing chronic conditions or addressing lifestyle factors. Treatment depends on the underlying cause and severity.
Symptoms linked to abnormal MCV
MCV itself doesn’t cause symptoms, but abnormal levels often point to underlying conditions such as anemia, which can cause symptoms such as:
- Fatigue
- Pale or yellowish skin
- Shortness of breath
- Dizziness or lightheadedness
- Cold hands and feet
These symptoms can be subtle and overlap with other health issues, which is why blood testing is important for accurate diagnosis. People at higher risk of abnormal MCV levels, include older adults and those with chronic health conditions, restrictive diets and alcohol use.
What should you do if your MCV levels are high or low?
If your CBC test shows that your MCV is outside the normal range, don’t panic—this result is just one piece of the puzzle. Here’s what you can do:
- Confirm with your healthcare provider: MCV is just one part of your CBC. Your provider will review other markers and your symptoms
- Get follow-up tests: Iron studies, vitamin B12 and folate level tests, or liver function tests may be needed to get more information in support of a diagnosis
- Review medications and lifestyle: Certain drugs, alcohol use, or chronic illnesses can affect MCV
- Monitor trends: Sometimes changes are temporary. Repeat testing helps spot patterns
- Avoid self-treatment: Taking supplements without guidance can cause harm. Always consult a healthcare professional
Remember: Abnormal MCV levels don't always indicate a problem, but it’s a signal to dig deeper. Early action can prevent complications and improve overall health.
How to check your MCV levels
The easiest way to check your MCV is through a CBC test. Labcorp OnDemand offers a Complete Blood Count (CBC) Test that measures:
- Hematocrit
- Hemoglobin
- MCV
- Mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC)
- Red cell distribution width (RDW)
- Platelet count
- Red and white blood cell (RBC and WBC) counts
This test can help identify potential issues with your red blood cells and guide further evaluation.
MCV is just one component used to assess your health through a CBC test. Abnormal results don’t always mean something is wrong, but they do warrant a conversation with your doctor.
Ready to learn more about your blood health?
Purchase Labcorp OnDemand’s Complete Blood Count (CBC) Test today to get insights into your red blood cell health and overall wellness.
