Mean corpuscular hemoglobin (MCH) refers to the amount of hemoglobin in a red blood cell. High or low numbers may indicate a vitamin deficiency or certain types of anemia.
An MCH value refers to the average quantity of hemoglobin present in a single red blood cell. Hemoglobin is the protein in your red blood cells that transports oxygen to the tissues of your body.
Your MCH value is related to two other values, mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC). Together, MCH, MCV, and MCHC are sometimes referred to as red blood cell indices.
This article explores healthy MCH levels, how doctors test them, and what the results mean.
Doctors determine your MCH level with a complete blood count (CBC) panel. Your doctor will order a CBC panel to screen for many conditions, including anemia and infection. The CBC tests red and white blood cells, as well as platelets. MCH is calculated using red blood cell analysis.
MCH is calculated by dividing the amount of hemoglobin in a given blood volume by the number of red blood cells present.
MCH ranges
As part of a CBC, your doctor will measure your MCH levels in picograms (pg) per red blood cell. The typical ranges are:
| MCH ranges | MCH levels (pg) |
|---|---|
| low | under 27 |
| typical | 27 – 31 |
| high | over 31 |
An MCH value calculated below 27.5 pg is considered low MCH. This means that there’s a low amount of hemoglobin present per red blood cell.
Causes of low MCH
A low MCH value typically indicates the presence of iron deficiency anemia. Iron is important for the production of hemoglobin. Your body absorbs a small amount of iron that you eat to produce hemoglobin.
Some of the general causes of iron deficiency include eating a diet that is low in iron, major surgery or trauma, or blood loss.
In rare cases, low MCH can be caused by a genetic condition called thalassemia. In this condition, the production of hemoglobin is limited. This means there aren’t as many red blood cells circulating in your bloodstream.
Low MCH levels may also be caused by autoimmune diseases.
Symptoms of low MCH
If you have a low MCH value, you may experience the following symptoms:
Should I worry if my MCH is low?
Causes for concern depend on how low your levels are and the underlying cause. A doctor can determine what’s causing your low levels of MCH and whether you need treatment.
Treatment for low MCH caused by iron deficiency include:
- adding iron-rich foods to your diet (there are vegetarian options)
- taking iron supplements
- receiving iron supplementation through an IV
In rare cases, such as when symptoms are severe or blood loss has occurred, you may need a blood transfusion.
An MCH value calculated above 33.2 pg is considered high MCH. This means that there is a larger amount of hemoglobin present per red blood cell.
Causes of high MCH
High MCH value can often be caused by anemia due to a deficiency of B vitamins, particularly B-12 and folate. Both of these vitamins are required by your body to make red blood cells.
These types of anemia can develop if your diet is low in B vitamins or if your body does not absorb B-12 or folate properly. It’s important to be aware of the symptoms of a B-12 deficiency.
High MCH levels may also be a result of overactive thyroid, liver disease, COPD, or other lung diseases.
Symptoms of high MCH
If you have a high MCH value, you may experience the following symptoms:
- shortness of breath
- chest pain
- fast heartbeat
- fatigue or weakness
- very pale or yellowish skin
- headache
If you have anemia that’s due to B-12 deficiency, you may also experience:
If you have anemia due to folate deficiency, you could experience the following additional symptoms:
- diarrhea
- decrease in appetite
- irritability
- a smooth or sensitive tongue
Should I be concerned if my MCH is high?
A doctor can help you determine whether you need treatment. The treatments for abnormally high MCH levels depend on how high your levels are and the underlying cause.
Treatment for anemias caused by B-12 or folate deficiencies are commonly treated by supplements of these vitamins to further boost your B-12 and folate levels or, if absorption is a problem, prescribe B-12 injections.
Your doctor may also recommend lifestyle changes and adding foods rich in vitamin B-12 and folate to your diet.
Management of high MCH due to hyperthyroidism, liver disease, or lung disease typically includes managing the underlying condition.
The outlook for people with abnormal MCH values depends on the condition that’s causing it.
Low MCH values are often caused by iron deficiency anemia. Typically, this condition can be treated with lifestyle changes, including consuming iron-rich foods and taking iron supplements.
In the rare case that your low MCH value is caused by thalassemia, you may require blood transfusions if your symptoms are severe. If you have an autoimmune disorder, you may be prescribed steroids or other immunosuppressants.
High MCH values caused by a deficiency of the vitamins B-12 or folate can also often be treated with changes to your lifestyle that include dietary modifications and supplements or injectable B-12.
Other causes of high MCH, such as hyperthyroidism or lung or liver diseases, require addressing the underlying condition.
If you’re concerned about your MCH results, be sure to talk to your doctor about them. Together, you can decide on the best way to move forward.