Unit Converter
MCV – Mean Corpuscular Volume
(Average Size/Volume of Red Blood Cells – Key Marker in Classifying Anemia)
Synonyms
- MCV
- Mean cell volume
- Mean corpuscular volume
- Average red cell volume
- RBC volume index
Units of Measurement
- fL (femtoliters)
- µm³ (cubic micrometers)
- cu µm
- cubic µm
Key Unit Conversions
1 fL=1 µm3=1 cubic µm1\ \text{fL} = 1\ \text{µm}^3 = 1\ \text{cubic µm}1 fL=1 µm3=1 cubic µm
So:
- 80 fL = 80 µm³
- 95 fL = 95 µm³
- 120 fL = 120 µm³
All units represent the same value.
Description
MCV indicates the average volume of a single red blood cell (RBC).
Calculated as:
MCV (fL)=Hematocrit (L/L)RBC count (×10¹²/L)×1000\text{MCV (fL)} = \frac{\text{Hematocrit (L/L)}}{\text{RBC count (×10¹²/L)}} \times 1000MCV (fL)=RBC count (×10¹²/L)Hematocrit (L/L)×1000
It is one of the 3 core RBC indices:
- MCV
- MCH
- MCHC
MCV is essential for classification of anemia into:
- Microcytic (low MCV)
- Normocytic (normal MCV)
- Macrocytic (high MCV)
Physiological Role
MCV itself is not a physiologic molecule; it reflects:
- Erythropoiesis
- Iron availability
- DNA synthesis
- Cell membrane structure
- RBC hydration status
It is a major surrogate marker for nutritional, genetic, and hematologic disorders.
Clinical Significance
LOW MCV
(Most common abnormality)
Primary Causes
- Iron Deficiency Anemia (IDA) - classic
- Thalassemia Trait (very low MCV with normal RDW)
- Anemia of Chronic Disease (mildly low)
- Sideroblastic Anemia
- Lead Poisoning
- Chronic blood loss
- Copper deficiency (rare)
Patterns
- Low MCV
- Low MCH
- Low MCHC
- High RDW (except in thalassemia trait)
HIGH MCV
Megaloblastic Causes
- Vitamin B12 deficiency
- Folate deficiency
- Methotrexate
- Antiretroviral drugs
- Hydroxyurea
Non-Megaloblastic Causes
- Alcoholism
- Liver disease
- Hypothyroidism
- Reticulocytosis (retics are large)
- Myelodysplastic syndromes (MDS)
- Aplastic anemia
Patterns
- High MCV
- Normal or high MCH
- Normal MCHC
- Hypersegmented neutrophils in megaloblastic anemia
NORMAL MCV
(MCV normal but RBC indices abnormal)
Occurs in:
- Acute blood loss
- Hemolytic anemia (early)
- Chronic kidney disease
- Combined nutritional deficiencies (B12 + iron)
- Early IDA
- Bone marrow failure
Reference Intervals
(WHO + Tietz 8E + Mayo + ARUP)
Adults
- 80 – 100 fL
(= 80–100 µm³)
Children
| Age | MCV |
| Newborn | 95–120 fL |
| 2–6 months | 85–105 fL |
| 6 months–6 years | 70–86 fL |
| >6 years | 76–90 fL |
Interpretation Flags
- MCV < 80 fL → microcytosis
- MCV > 100 fL → macrocytosis
- MCV > 110 fL → consider megaloblastic anemia or MDS
- MCV > 120 fL → severe B12/folate deficiency
Diagnostic Uses
1. Anemia Classification
The primary use of MCV.
2. Differentiate Causes of Microcytosis
- IDA vs thalassemia trait
- Sideroblastic anemia vs chronic disease
3. Detect Nutritional Deficiencies
- B12
- Folate
4. Alcoholism Screening
Macrocytosis is common even without anemia.
5. Evaluate Bone Marrow Function
Macrocytosis in MDS.
6. Monitor Treatment
- Iron therapy response
- Vitamin supplementation
- Reticulocyte-related changes
7. RBC Morphology Correlation
MCV gives a quantitative summary; smear confirms morphology.
Analytical Notes
- Automated RBC counters measure MCV directly.
- Cold agglutinins can falsely increase MCV.
- Hyperglycemia and high WBC count falsely increase MCV.
- Dehydration may concentrate Hct, altering MCV indirectly.
- Always correlate with MCH, MCHC, RDW.
Clinical Pearls
- Thalassemia trait → very low MCV but normal RDW.
- Early IDA → MCV may be normal; MCH falls first.
- Alcoholism is the most common non-megaloblastic cause of high MCV.
- Combined deficiencies (iron + B12) may produce normal MCV with wide RDW.
- Reticulocytosis temporarily increases MCV because retics are larger cells.
Interesting Fact
Newborns naturally have the largest RBCs in human physiology — an evolutionary adaptation to fetal oxygen transport - giving them physiologic macrocytosis.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Hematology
- WHO Hematology Reference Ranges
- Mayo Clinic Laboratories - RBC Indices
- ARUP Consult - CBC Interpretation
- MedlinePlus / NIH - CBC & RBC Indices