MCV vs MCH compares two red blood cell indices reported as part of a full blood count. MCV, or mean cell volume, measures the average size of red blood cells. MCH, or mean cell haemoglobin, estimates the average amount of haemoglobin in each red blood cell. They are related but not interchangeable. Clinicians interpret them with haemoglobin, red cell count, MCHC, RDW and other tests to describe anaemia patterns. Neither value identifies the cause of anaemia on its own.
What Is MCV?
MCV stands for mean cell volume or mean corpuscular volume.
It represents the average volume of a red blood cell and is usually reported in femtolitres (fL).
MCV helps describe red cells as:
- microcytic — smaller than the local reference interval
- normocytic — within the local interval
- macrocytic — larger than the local interval
MedlinePlus describes MCV as a measure of the average size of red blood cells.
This classification is useful because different physiological problems tend to produce different cell-size patterns, but the categories are not diagnoses.
What Is MCH?
MCH stands for mean cell haemoglobin or mean corpuscular haemoglobin.
It estimates the average mass of haemoglobin in each red blood cell and is usually reported in picograms (pg).
Haemoglobin is the iron-containing protein that carries oxygen.
If the average red cell contains less haemoglobin, the MCH may be lower. MCH often moves in the same general direction as MCV because smaller cells frequently contain less haemoglobin.
MedlinePlus describes MCH as the average amount of haemoglobin in a single red blood cell.
MCV vs MCH: Quick Comparison
| Feature | MCV | MCH |
|---|---|---|
| Full name | Mean cell volume | Mean cell haemoglobin |
| Measures | Average red-cell size | Average haemoglobin mass per red cell |
| Typical unit | fL | pg |
| Main use | Classifies cells as microcytic, normocytic or macrocytic | Adds information about haemoglobin content |
| Part of | Full blood count / RBC indices | Full blood count / RBC indices |
| Diagnoses a cause alone? | No | No |
The indices are derived from the same red-cell dataset, which is why they often correlate.
What Are Example Reference Ranges?
Reference intervals vary by laboratory.
Gloucestershire Hospitals NHS Foundation Trust currently lists adult examples of:
- MCV: 80–100 fL
- MCH: 27–32 pg
MedlinePlus publishes similar but not identical examples.
These values demonstrate why LabWise Biomed does not present one range as universal. Laboratories can use different analysers, methods and locally validated populations.
Always use the interval printed next to the result.
How Is MCV Used to Classify Anaemia?
Anaemia is defined primarily by haemoglobin relative to the appropriate reference interval, not by MCV alone.
Once anaemia is present, MCV helps describe the red-cell pattern.
Microcytic pattern
A low MCV means the average red cell is smaller than expected.
Possible contexts include:
- iron deficiency
- thalassaemia
- some chronic inflammatory states
- selected disorders of haem synthesis
This does not mean a low MCV automatically equals iron deficiency.
Normocytic pattern
A normal MCV with low haemoglobin creates a normocytic anaemia pattern.
Possible contexts include:
- acute blood loss
- chronic disease
- kidney disease
- bone-marrow disorders
- haemolysis in some settings
Again, further tests are needed.
Macrocytic pattern
A high MCV means larger-than-expected red cells.
Possible contexts include:
- vitamin B12 deficiency
- folate deficiency
- alcohol exposure
- liver disease
- some medicines
- bone-marrow disorders
- reticulocytosis
See anaemia types explained for the broader framework.
How Does MCH Add Information?
MCH tells clinicians how much haemoglobin, on average, is present per red cell.
A low MCH often accompanies microcytosis because small cells tend to contain less haemoglobin.
This is common in iron-restricted patterns and some haemoglobin disorders.
However, MCH is closely related mathematically to red-cell size, so it does not provide completely independent information.
It is usually interpreted with:
- MCV
- MCHC
- haemoglobin
- haematocrit
- red cell count
- RDW
- blood film
- ferritin and iron studies where appropriate
What Does “Hypochromic” Mean?
Hypochromia refers to red cells with reduced haemoglobinisation, giving increased central pallor on a blood film.
In automated indices, a low MCH or MCHC can support a hypochromic pattern.
The term should not be reduced to one number. A blood film and the other indices can help laboratory professionals understand cell morphology more directly.
Why MCV and MCH Often Move Together
MCV measures cell size, while MCH measures haemoglobin mass per cell.
A smaller cell has less physical volume in which to contain haemoglobin, so low MCV and low MCH commonly occur together.
Likewise, larger cells can have higher MCH because each cell contains more haemoglobin mass even if the concentration of haemoglobin inside the cell is not abnormally high.
This leads to a useful distinction:
- MCH = amount of haemoglobin per cell
- MCHC = concentration of haemoglobin within the packed red-cell volume
They should not be confused.
What If MCV Is Low but MCH Is Normal?
Discordant patterns can occur, especially around reference-limit boundaries or where the indices are only mildly abnormal.
Possible reasons include:
- analytical variation
- mixed red-cell populations
- early or evolving deficiency
- overlapping conditions
- local reference-interval differences
One unexpected combination should be interpreted with the whole FBC rather than forcing it into a textbook category.
What If MCV Is Normal but Anaemia Is Present?
A normal MCV does not exclude anaemia.
Haemoglobin can be low while average cell size remains within the reference interval.
Normocytic patterns occur in several settings and can also appear when two opposing processes average out. For example, a mixture of smaller and larger red cells can produce an average MCV that looks normal.
RDW and the blood film may reveal more variation than the average alone shows.
Relationship to Iron Studies
When iron deficiency is being considered, MCV and MCH can support the pattern but do not measure body iron stores.
Tests such as ferritin, transferrin saturation and other iron studies provide different information.
A person can have iron deficiency before MCV becomes clearly low, and microcytosis can have causes other than iron deficiency.
See iron studies explained for the laboratory distinction.
MCV, MCH and the Full Blood Count
A full blood count provides multiple related measurements:
- haemoglobin
- red cell count
- haematocrit
- MCV
- MCH
- MCHC
- RDW where reported
- white cell count and differential
- platelet count
Looking at the pattern is more informative than isolating one index.
For example, low haemoglobin with low MCV, low MCH and low ferritin creates a different laboratory pattern from low haemoglobin with high MCV and reduced vitamin B12.
The indices help organise the investigation; they do not replace it.
See full blood count explained for the full panel.
How Are MCV and MCH Calculated?
Modern analysers directly measure or derive several red-cell parameters from millions of cells.
Conceptually:
- MCV represents average red-cell volume.
- MCH can be derived from the relationship between haemoglobin concentration and red-cell count.
Readers do not need to calculate these manually because the analyser reports them automatically.
The important practical issue is understanding what each value represents.
Factors That Can Affect Interpretation
Interpretation can be influenced by:
- recent transfusion
- reticulocytosis
- mixed nutritional deficiencies
- pregnancy
- age
- alcohol exposure
- medicines
- liver disease
- haemoglobin disorders
- analytical interference
A transfusion, for example, can create a mixed population of donor and recipient cells that changes the average indices.
Why One Index Cannot Diagnose Anaemia Type
The labels microcytic, normocytic and macrocytic describe cell size.
They do not establish cause.
A low MCV can occur in both iron deficiency and thalassaemia. A high MCV can occur in vitamin deficiency, liver disease, alcohol exposure and other settings.
Clinical history and additional laboratory data are required to distinguish these possibilities.
Key Points
- MCV measures average red-cell size.
- MCH measures average haemoglobin mass per red cell.
- Both are part of the red-cell indices on a full blood count.
- MCV helps classify anaemia patterns by cell size.
- MCH adds information about haemoglobin content per cell.
- The two often move together but are not identical.
- Reference ranges vary by laboratory.
- Neither value can identify the cause of anaemia alone.
References
- MedlinePlus. Red Blood Cell (RBC) Indices. https://medlineplus.gov/lab-tests/red-blood-cell-rbc-indices/
- MedlinePlus. MCV (Mean Corpuscular Volume). https://medlineplus.gov/lab-tests/mcv-mean-corpuscular-volume/
- Gloucestershire Hospitals NHS Foundation Trust. Haematology reference ranges. https://www.gloshospitals.nhs.uk/our-services/services-we-offer/pathology/haematology/haematology-reference-ranges/
This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional about your results.
Full Blood Count Explained: What FBC Measures
Anaemia Explained: Types, Causes, and How Blood Tests Diagnose It
Iron Studies Explained: Serum Iron, Ferritin, TIBC and Transferrin Saturation
Frequently Asked Questions
What is the difference between MCV and MCH?
MCV measures the average size of red blood cells, while MCH estimates the average amount of haemoglobin contained in each red blood cell.
What does a low MCV mean?
A low MCV describes a microcytic red-cell pattern. Iron deficiency is one possible cause, but thalassaemia and other conditions can also produce microcytosis, so the result is not diagnostic by itself.
What does a low MCH mean?
A low MCH means the average red cell contains less haemoglobin than the laboratory reference interval. It often accompanies microcytosis and iron-restricted patterns but has several possible explanations.
Can MCV be normal when haemoglobin is low?
Yes. Anaemia with an MCV inside the reference interval is described as a normocytic pattern. The cause is investigated using the wider blood count, clinical context and additional tests.
Are MCV and MCH enough to diagnose iron deficiency?
No. They can support an iron-restricted red-cell pattern, but iron status is assessed with tests such as ferritin and other iron studies alongside the clinical context.
What are normal MCV and MCH ranges?
Ranges vary by laboratory. One current NHS example is MCV 80–100 fL and MCH 27–32 pg in adults, but the reference intervals printed on the individual laboratory report should be used.