What Does MCH on a Blood Test Mean?

Unless you went to medical school, even a "simple" procedure like a blood test can teem with unfamiliar terms and acronyms.

You might feel this way about mean corpuscular hemoglobin (MCH). It refers to the average amount of hemoglobin in a red blood cell.

MCH is one of the standard measurements in a complete blood count (CBC) test—a common test that many adults have at some point in their life.

This article explains the role of hemoglobin and how the MCH is determined during a CBC test. It also explains what may cause levels that are higher or lower than normal.

A blood sample being held with a row of human samples

Andrew Brookes / Getty Images

Definition of Hemoglobin

Human blood is made up of red blood cells, white blood cells, and platelets. Red blood cells are the ones that carry oxygen and carbon dioxide throughout the body. Red blood cells are also known as erythrocytes.

Inside red blood cells is a protein called hemoglobin, which contains iron. Oxygen and carbon dioxide attach to hemoglobin. When combined with oxygen, hemoglobin is what gives blood its red color.

How Hemoglobin Is Measured

A patient may get a CBC test during an annual checkup or when a physician needs more information to form a diagnosis. This step is likely to occur if a patient has symptoms of a condition that affects the blood cell count, such as anemia.

A CBC is technically a series of tests that gathers information on a patient's red blood cells, white blood cells, and platelets. The report details how many cells there are in the blood, as well as the physical characteristics of the cells, such as their size, shape, and content.

A person's MCH value typically parallels their mean corpuscular volume (MCV) level, which measures the actual size of the red blood cells.

For this reason, a doctor may decide to skip this part of the CBC. But this doesn't mean MCH levels are useless. They can be used, for example, to determine which type of anemia a person has.

Common Blood Tests

A CBC is a common blood test, but it's not the only one. Other blood tests include blood chemistry and blood enzyme tests and tests to assess for heart disease risk.


Understanding MCH in Test Results

The normal range of the MCH is between 27 and 31 picograms/cell.

There are specific symptoms and conditions associated with MCH levels that are both lower and higher than normal. Here is a general overview of what these levels can say about a person's health.

Low MCH Levels

Registering an MCH level below 27 picograms/cell is most commonly associated with anemia. It could also be a sign of:

  • An autoimmune disease
  • Cancer
  • Deficiency of certain nutrients, such as vitamin B12 or folic acid
  • Internal or external blood loss, often resulting from surgery, injury, or menstrual bleeding
  • Iron deficiency, almost always caused by blood loss
  • Kidney disease
  • Liver disease
  • Thalassemia, a common, inherited blood disorder caused by genetic mutations in the hemoglobin genes

People with low MCH levels may experience symptoms including:

  • Cold hands and feet
  • Dizziness
  • Fatigue
  • Pale skin (pallor)
  • Shortness of breath
  • Weakness

High MCH Levels

Having an MCH level above 31 picograms/cell is most commonly associated with the following conditions:

People with high MCH levels may experience symptoms including:

  • Blood clots
  • Blurred or double vision
  • Dizziness
  • Headaches
  • Itching

Next Steps for Abnormal MCH Levels

If your MCH levels appear to be higher or lower than normal, your physician will do additional testing to determine the cause. The treatment options will depend on the cause.

There are many reasons why MCH levels fall outside the normal range. It could be a side effect from a medication; it could even be because you live in a high-altitude region. The important thing is to try to relax and refrain from fearing the worst.

Summary

The mean corpuscular hemoglobin (MCH) measurement is part of a complete blood count (CBC) test. The MCH represents the average amount of hemoglobin in a cell. Hemoglobin is a protein in red blood cells that carries oxygen and carbon dioxide.

A low MCH can indicate conditions like anemia and thalassemia. High levels might be due to lung or kidney disease. If your levels are abnormal, your healthcare provider will determine the cause and appropriate treatment.

A Word From Verywell

MCH levels represent only one piece of what you might call the "healthcare puzzle." Other factors, including family history and lifestyle, also provide crucial information about your overall health and the likelihood of having a particular condition. Uncovering this information requires that you be honest and open with your healthcare provider. Doing so can put your MCH levels into clearer focus.

Frequently Asked Questions

  • What causes low MCH in a blood test?

    Low levels of mean corpuscular hemoglobin (MCH) can be caused by anemia, iron deficiency, vitamin B12 or folic acid deficiency, cancer, kidney disease, autoimmune diseases, liver disease, or thalassemia (a hemoglobin disorder). Low MCH can also be caused by blood loss due to surgery, an injury, menstrual bleeding, or bleeding in the gastrointestinal tract.

  • What is in blood?

    Human blood consists of plasma, red blood cells, white blood cells (leukocytes), and platelets (thrombocytes). Hemoglobin is found in red blood cells.

  • What is MCV?

    Mean corpuscular volume (MCV) measures the average size of red blood cells in a blood sample.

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7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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