What Is MCH?

Mean corpuscular hemoglobin (MCH) is one way to measure the health of red blood cells. Abnormal MCH levels can help diagnose conditions like anemia.

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Mean corpuscular hemoglobin (MCH) is a measurement of the average amount of hemoglobin within a red blood cell. Hemoglobin is a protein that carries oxygen from the lungs to different cells throughout the body. The cells use the oxygen to grow and reproduce.

A blood test can reveal your MCH level. MCH that is lower or higher than normal may indicate you have a condition such as anemia or high cholesterol.

What Does MCH Reveal? 

MCH is measured as part of a complete blood count. A complete blood count measures various aspects of your blood, including the health of your red blood cells. MCH is one measurement that can shed light on the health of your red blood cells. 

Your healthcare provider might order a complete blood count either as part of a routine check-up or to help diagnose certain conditions. 

The main condition MCH can help diagnose is anemia. Anemia is a condition that develops when your body produces too few healthy red blood cells. With limited red blood cells, people with anemia don’t get enough oxygen-rich blood throughout their body. The lack of oxygen can make you feel tired and weak.

The normal range for MCH is 27 to 31 picograms per cell. Anything below or above that might indicate an underlying health condition. 

What Does Low MCH Mean?

An MCH level below the normal range may be a sign of hypochromic anemia. This type of anemia develops when there is not enough hemoglobin in the blood. 

In the U.S., lack of iron is the most common cause of hypochromic anemia. Iron is an important part of hemoglobin production. Without enough iron, hemoglobins cannot be produced. This type of anemia is often referred to as iron-deficiency anemia.  

Iron-deficiency anemia can develop for several reasons, including:

  • Blood loss: This can be from heavy periods, bleeding within the gastrointestinal tract (like from inflammatory bowel disease), surgery, or traumatic injuries.
  • Problems absorbing iron: This can be due to rare genetic conditions, endurance sports, intestinal and digestive conditions, and surgery on your stomach or intestines.  
  • Kidney disease: You may not make enough erythropoietin, a hormone your body needs to produce red blood cells.
  • Chronic conditions that cause inflammation: It might be hard for your body to use iron.
  • Not enough iron in your diet: This cause is not as common in the U.S. When it does happen, it would most likely affect children between 9 months and 1 year.

Symptoms of Low MCH

If you have a low level of MCH and are determined to have iron deficiency anemia, you might not have any symptoms. If you have been experiencing symptoms, they might include:

  • Tiredness 
  • Shortness of breath 
  • Chest pain 
  • Fatigue 
  • Dizziness or lightheadedness 
  • Cold hands and feet 
  • Pale skin

What Does High MCH Mean?

An MCH level above normal levels may indicate that you have anemia due to low folate or B12 levels. Folic acid, or vitamin B9, helps in the production of red blood cells. Vitamin B12 is necessary for the development of healthy red blood cell formation.

Folate-deficiency anemia can develop if you:

  • Don’t take in enough folate in your diet (found in liver and green, leafy vegetables)
  • Drink heavily in the long term
  • Use certain medications, including Azulfidine (sulfasalazine) and Dyrenium (triamterene)

Vitamin B12–deficiency anemia can develop if your body can’t properly absorb vitamin B12. This poor absorption can happen because of:

  • A lack of intrinsic factor (a protein that helps your body absorb vitamin B12)
  • Heavy alcohol use
  • Certain medicines, such as heartburn medicine and the diabetes medication metformin
  • Certain conditions, such as celiac disease, inflammatory bowel disease, and vitiligo
  • Stomach surgery

While rare, you can also develop vitamin B12–deficiency anemia if your diet doesn’t include enough vitamin B12.

MCH levels may also be high if you have anemia caused by chemotherapy.

Falsely high MCH levels may also appear in the setting of high cholesterol.

Symptoms of High MCH

If you have high MCH due to anemia, you might experience symptoms of the anemia. For both folate- and vitamin B12–deficiency anemia, that can include fatigue, weakness, headache, and paleness.

With folate–deficiency anemia, you may experience sore mouth and tongue.

Because vitamin B12 is needed for proper brain and nerve function, you may experience problems with the following if you have vitamin B12–deficiency anemia:

  • Walking
  • Movement
  • Thinking
  • Smell
  • Taste
  • Vision

Editor’s Note: Even if your MCH is within a normal range, it is still possible to have normochromic anemia. This type of anemia can develop for multiple reasons, including sudden blood loss or kidney failure.

How Are Abnormal MCH Levels Treated?

High and low MCH levels are treated differently based on which disease or medical condition is causing the abnormal levels. 

A healthcare provider will first have to determine why your MCH levels are low or high. They will likely look at the other results of your complete blood count for a full picture. There are other measurements of your red blood cells’ health:

  • Mean corpuscular volume (MCV): Measures of the average size of your red blood cells
  • Mean corpuscular hemoglobin concentration (MCHC): Measures the amount of hemoglobin a red blood cell has relative to the cell's volume
  • Red cell distribution width (RDW): Measures differences in the volume and size of your red blood cells 

Anemia is usually what’s associated with abnormal MCH levels. If it’s determined that anemia is causing the abnormal MCH levels, the healthcare provider will then have to figure out what is causing the anemia. Depending on the cause and how severe the anemia is, you will receive a tailored treatment. 

Treatment for anemia might include:

  • Medication
  • Supplements
  • Blood transfusion
  • Blood and bone marrow transplant
  • Surgery
  • Dietary changes

A Quick Review

MCH stands for mean corpuscular hemoglobin. MCH measures the average amount of hemoglobin within a red blood cell. MCH is one measurement of your red blood cells’ health that is recorded during a complete blood count. 

The normal range for MCH is 27 to 31 picograms per cell. Anything above or below that may indicate an underlying condition, usually a type of anemia. Low levels of MCH can indicate iron-deficiency anemia while high levels of MCH can signal anemia caused by low levels of folic acid or vitamin B12.

A healthcare provider will determine what is causing your abnormal MCH levels. If it’s anemia, they will determine what type of anemia it is and what is causing it. Then, they will be able to manage the cause and work to get your levels back to normal levels.

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