MCH value: what this number says about your red blood cells

Your MCH value is the average amount of haemoglobin inside a red blood cell, expressed in picograms. At most Dutch labs the range runs from about 27 to 33 pg. If your report says 30, you are sitting in the middle of it.

MCH is a calculation, not a separate measurement. The lab divides your haemoglobin by your red cell count. There is nothing more to it.

Here is what I find most useful about this value: on its own it says almost nothing, but it completes the pattern. More on that below.

What is MCH?

MCH stands for mean corpuscular haemoglobin, the average amount of oxygen-carrying protein per red blood cell. A picogram is a trillionth of a gram, so the numbers are small. A low MCH means your cells are on average paler, a high one that they are fuller.

Doctors call pale cells hypochromic. You will see that word on your report if someone has looked at the blood under a microscope.

The value belongs to the complete blood count, sitting among the other red cell indices.

What is a normal MCH value?

In adults the reference range usually runs from 27 to 33 pg, with small differences between laboratories. Unlike haematocrit, there is barely any difference between men and women, because MCH is a ratio per cell rather than a share of volume.

You can look up your own number below.

This grid helps you read your result. It is not a diagnosis, and a value just outside the range is unremarkable in many people.

What does a low MCH mean?

A low MCH means your red blood cells carry too little haemoglobin on average. Iron deficiency is by far the most common cause, because you cannot build haemoglobin without iron. The cells become both smaller and paler, so your MCV usually falls with it.

The second cause that genuinely matters is thalassaemia, an inherited disorder of haemoglobin production. In thalassaemia the MCH is often strikingly low while iron is normal, and laboratory testing can separate the two (PMID 27183541).

That distinction matters more than it looks. Taking iron when you are not iron deficient solves nothing.

Picture two people with an MCH of 24 pg. The first has a ferritin of 8 and heavy periods. The second has a ferritin of 90 and a relative with thalassaemia.

Same number, two different routes. Iron is the answer for only one of them.

Chronic illness can lower MCH slightly too, and in heart failure the combination of iron deficiency and abnormal red cell indices is well described (PMID 28386910).

What does a high MCH mean?

A high MCH usually means your red blood cells are larger than normal, because a bigger cell holds more haemoglobin. The classic causes are a vitamin B12 or folate deficiency and regular alcohol use. Some medicines raise it as well.

With a raised MCH the follow-up question is nearly always the same: what are your B12 and folate doing. Thuisarts and the NHG guidelines describe that route for Dutch primary care.

A high MCH without symptoms and with normal B12 is often not worrying. Do raise it if it is new.

MCH or MCV, what is the difference?

MCV measures how large an average red cell is; MCH measures how much haemoglobin sits inside it. Because larger cells hold more haemoglobin, the two nearly always move the same way. That is exactly why MCH adds little once you already know the MCV.

Sometimes they diverge, and that is when it gets interesting. A low MCH with a normal MCV points more towards an early deficiency than a low MCH with an already reduced MCV.

Our guide to the MCV value goes deeper into cell size.

Pregnancy gives another reason to read the indices together. Research comparing red cell indices with ferritin as a marker of iron deficiency in pregnancy found the indices alone are not enough (PMID 41160552).

Which values do you read beside your MCH?

Always read your MCH together with your MCV, your MCHC and your RDW. Between them those four describe the size, the filling and the variation of your red blood cells. A single abnormal index rarely changes management; a pattern across all four can.

• MCHC sets the amount of haemoglobin against the volume of the cell.
• RDW shows how much your cells vary in size.
• Ferritin is the value that reveals an iron shortfall earliest.

To have these indices measured, they are part of the blood count in our basic health checkup. You can also pick them individually through your own custom blood test.

My advice: do not read your MCH as a standalone figure. Put it next to your MCV and your ferritin, and discuss the pattern with your GP if one of the three is off.

This information is general and does not replace medical advice. Blood results from Vitalcheck are reviewed by a BIG-registered doctor. Always discuss an abnormal result with your own GP.

References

• Laboratory diagnosis of thalassemia. Int J Lab Hematol, 2016. PMID 27183541
• Iron deficiency and red cell indices in patients with heart failure. Eur J Heart Fail, 2018. PMID 28386910
• Red blood cell indices versus serum ferritin as surrogate markers of iron deficiency during pregnancy. PLoS One, 2025. PMID 41160552
• NHG guidelines and Thuisarts, on the workup of anaemia in Dutch primary care