What MCH Actually Measures
MCH — mean corpuscular haemoglobin — is the average amount of haemoglobin packed into each red blood cell. Haemoglobin is the protein that carries oxygen, so MCH is a quick measure of how well-filled your red cells are. It is calculated automatically as part of the full blood count (FBC), so you never order it on its own — it appears alongside the other red-cell indices, MCV and MCHC.
How MCH Is Reported in Australia
MCH is reported in picograms (pg) — a measure of mass per cell. Because it is calculated from your haemoglobin and red-cell count, small movements within the range are normal and not meaningful on their own.
Normal MCH Range
| Group | Typical MCH range (pg) |
|---|---|
| Adults | ~27–33 |
Ranges vary slightly between labs, so read your result against your own report. MCH almost always moves in the same direction as MCV (red-cell size), which is why the two are interpreted together.
What a Low MCH Means
A low MCH means your red cells carry less haemoglobin than usual — described as "hypochromic" (pale) cells, and usually seen with a low MCV (small, "microcytic" cells). The common causes are:
- Iron deficiency — by far the most common cause. Iron is needed to make haemoglobin, so when stores run low the cells are under-filled. This is usually confirmed with a ferritin and iron studies follow-up.
- Thalassaemia — an inherited condition affecting haemoglobin production, more common in people of Mediterranean, South-East Asian, Middle Eastern or African background.
- Anaemia of chronic disease in some cases.
What a High MCH Means
A high MCH usually goes with a high MCV (large, "macrocytic" cells). Common causes include:
- Vitamin B12 or folate deficiency — the classic cause; see our guide to B12 and folate deficiency.
- Liver disease and heavy alcohol use.
- An underactive thyroid (hypothyroidism) and some medications.
Occasionally MCH reads falsely high for technical reasons (such as very high blood fats or cold agglutinins), which the lab will usually flag.
MCH vs MCV vs MCHC
These three red-cell indices are easy to mix up:
- MCV — the average size of your red cells.
- MCH — the average amount of haemoglobin per cell.
- MCHC — the concentration of haemoglobin within each cell.
Together they let your GP classify anaemia as microcytic (small cells — think iron deficiency), normocytic, or macrocytic (large cells — think B12/folate), which points to the likely cause and the next test.
When MCH Matters
MCH is most useful when it is abnormal and read in context — for example, a low MCH and low MCV in someone who is tired and pale strongly suggests iron deficiency and will usually prompt iron studies. On its own, a borderline MCH with an otherwise normal FBC is rarely a concern.
Will Medicare Cover It?
Yes. MCH is part of the full blood count (FBC), one of the most commonly ordered tests in Australia. Medicare bulk-bills the FBC when your GP provides a referral, so you usually pay nothing out of pocket.
How to Track Your MCH Over Time
MCH is most informative as part of the whole FBC trend — watching MCH and MCV together as iron or B12 treatment takes effect is the clearest way to see your red cells recover. Keeping each FBC side-by-side over time makes that pattern obvious. You can store and chart every result with BloodTrack.
This guide is general information for an Australian audience and is not a substitute for personal medical advice. Reference ranges vary between laboratories — always read your result against your own lab's printed range, and discuss any abnormal result with your GP.