MCV Test
Also known as: Mean Corpuscular Volume, Mean Cell Volume
What is MCV?
MCV (Mean Corpuscular Volume) measures the average size of your red blood cells. It helps classify types of anemia based on whether red blood cells are smaller or larger than normal.[MedlinePlus (NIH)]
What This Test Measures
This test measures the average volume of red blood cells in femtoliters (fL). It is calculated from hematocrit and red blood cell count.[Cleveland Clinic]
Why It's Important
MCV helps determine the cause of anemia: microcytic (small cells) often means iron deficiency, while macrocytic (large cells) suggests B12 or folate deficiency.[MedlinePlus (NIH)]
Abnormal MCV can indicate nutritional deficiencies, bone marrow problems, or chronic diseases.[Cleveland Clinic]
Who Should Get This Test?
MCV is routinely measured as part of a complete blood count, especially when evaluating anemia.
Risk Factors
- Anemia symptoms (fatigue, weakness, pale skin)
- Heavy alcohol use
- Vegetarian or vegan diet (B12 deficiency risk)
- History of gastric surgery or celiac disease
- Taking medications that affect folate (methotrexate, anticonvulsants)
- Chronic gastrointestinal conditions
- Family history of thalassemia
- Iron deficiency symptoms
Screening Schedule
Part of routine CBC; essential when investigating anemia or monitoring response to treatment for nutritional deficiencies.
What Happens During the Test
A blood sample is drawn from a vein. MCV is calculated automatically by the hematology analyzer from hematocrit and red blood cell count, or measured directly using electrical impedance.
Duration
5-10 minutes for blood draw; results typically available same day
Discomfort Level
Minimal discomfort from needle insertion
Risks & Side Effects
Standard blood draw with minimal risks.
- •Brief pain at needle site
- •Small bruise may develop
- •Rare: lightheadedness
- •Very rare: infection at puncture site
Normal Range
80 to 100 femtoliters (fL).
Note: Low MCV is called microcytic; high MCV is called macrocytic.
Source: MedlinePlus (NIH)Unit Conversion
Convert between fL (femtoliters) and μm³ (cubic micrometers)
| fL (femtoliters) | μm³ (cubic micrometers) |
|---|---|
| 70 | 70 |
| 80 | 80 |
| 90 | 90 |
| 100 | 100 |
| 110 | 110 |
High Values
High MCV (macrocytosis) can be caused by vitamin B12 or folate deficiency, alcoholism, liver disease, hypothyroidism, or certain medications.[Mayo Clinic]
Low Values
Low MCV (microcytosis) is commonly caused by iron deficiency anemia, thalassemia, chronic disease, or lead poisoning.[Cleveland Clinic]
Test Limitations & Accuracy
MCV interpretation has several limitations:
- ⚠MCV represents an average - mixed populations of small and large cells can yield normal MCV
- ⚠Reticulocytes (young red cells) are larger and can raise MCV
- ⚠Cold agglutinins can falsely elevate MCV
- ⚠Hyperglycemia can cause cell swelling and falsely elevated MCV
- ⚠Recent blood transfusion affects results
- ⚠MCV changes slowly and may not reflect acute deficiencies
- ⚠Concurrent iron and B12 deficiency can normalize MCV
Alternative & Complementary Tests
MCV is usually interpreted with other red cell indices:
To assess hemoglobin content per cell
To assess hemoglobin concentration within cells
To measure variation in red cell size
To visually examine red cell shape and size
To assess bone marrow response
When macrocytic anemia is found
Frequently Asked Questions
What does high MCV mean?
High MCV means your red blood cells are larger than normal (macrocytic). Common causes include vitamin B12 deficiency, folate deficiency, alcoholism, and liver disease. It needs evaluation to find the underlying cause.
Source: Mayo ClinicReferences
Related Condition Guides
Medical Disclaimer
This information is for educational purposes only and is not intended as medical advice. Always consult with a qualified healthcare provider for interpretation of test results and medical decisions.
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