Mean corpuscular hemoglobin (MCH) is a measure of the average amount of hemoglobin in the red blood cells (RBCs). The hemoglobin in red blood cells picks up oxygen in the lungs and delivers it to all the cells in your body as blood is circulated.

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How Is MCH Measured? 

MCH is part of a complete blood count (CBC). A CBC may be ordered as a routine test during a standard yearly physical, or as a diagnostic test when you have symptoms. A blood sample is drawn and sent to the lab for analysis using an automated instrument.

Depending on the sophistication of the lab instrument used, a CBC can include: 

• White blood cell (WBC) count
• WBC differential (number and percentage of different types of WBCs)
• RBC count
• Platelet count (small cells involved in clotting)
• Hemoglobin, reported as grams (g) of hemoglobin/deciliter (dL) of blood
• Hematocrit (the percentage of blood that is composed of RBCs)
• RBC indices (specific values of RBC size and hemoglobin content)

The RBC indices in a CBC include:

• Mean corpuscular volume (MCV): Average RBC size
• Mean corpuscular hemoglobin (MCH): Average amount of hemoglobin per red blood cell
• Mean corpuscular hemoglobin concentration (MCHC): Average amount of hemoglobin relative to the size of each red blood cell
• RBC distribution width (RDW): A measure of variation in red blood cell size

What Does MCH Value Indicate? 

Your MCH value indicates the average amount of hemoglobin in each of your blood cells. The amount is measured in picograms (pg) per cell.

The normal range for MCH in adults is between 27 and 31 pg/cell. An elevated or low MCH level can indicate various medical conditions.

MCH is not considered on its own:

• Smaller RBCs (low MCV) typically have less hemoglobin in each cell (and therefore a lower MCH)
• Larger RBCs (high MCV) have more hemoglobin in each cell.
• MCHC (hemoglobin relative to the size of the RBCs) gives further insight into what the MCH indicates.

Symptoms Associated With a High or Low MCH

Generally, high MCH and low MCH each cause similar symptoms, because they indicate different types of anemia. Anemia is a low number of RBCs or abnormal RBCs.

The overall consequence of anemia is that cells, tissues, and organs become low in oxygen. This oxygen deficiency causes the symptoms of anemia.

Symptoms of anemia include:

• Feeling more tired than usual
• Feeling colder than usual
• Pale or yellowish skin
• Dizziness and lightheadedness
• Headaches 
• Pounding in your ears
• A rapid heart rate
• Shortness of breath
• Feeling faint
• Passing out

These symptoms are nonspecific and can occur with many different disorders. If you see a healthcare provider, your diagnostic procedures will likely include blood tests, such as a CBC.

Causes of High or Low MCH

You can have a high MCH if you have enlarged RBCs. You can have a low MCH due to a deficiency in hemoglobin or having small RBCs.

Causes of high MCH include:

A low MCH is generally seen in microcytic anemia, which has the following causes:

• Iron deficiency
• Excessive bleeding due to trauma, gastrointestinal disease, or an ulcer
• Kidney disease
• Malnutrition
• Malabsorption
• Chronic disease
• Cancer

Interpreting and Using MCH in Diagnosis

If your MCH is high or low, ask your healthcare provider how they interpret this lab result. They can discuss with you how they use it to assess your health or diagnose a condition.

MCH is just one value considered when exploring the health of red blood cells and diagnosing anemia. The RBC count and other indices can indicate different types of anemia or other health problems. A healthcare provider can then determine what other tests are needed to complete a diagnosis.

Treatment for anemia varies depending on the type. It is important to diagnose the cause and type of anemia to administer the appropriate treatment.

Key Takeaways

• MCH is the average amount of hemoglobin in each red blood cell, measured as part of a complete blood count.
• Different types of anemia are the most common causes of an elevated MCH or a low MCH.
• MCH is not used alone; it is interpreted with the other results of the complete blood count to assess overall health and diagnose different types of anemia.