What Do MCH Blood Test Results Mean?

A mean corpuscular hemoglobin (MCH) blood test is a measurement of the amount of hemoglobin in red blood cells. It 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.

Low MCH levels can be a sign of anemia, autoimmune disease, and other issues. High MCH could be a sign of conditions like lung disease or an overactive thyroid. MCH levels can also be elevated due to heavy alcohol consumption and use of certain medications.

This article discusses reasons for low and high MCH levels and what happens next if you get an abnormal result.

MCH Blood Test Results

A normal MCH result 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 having high and low MCH levels may mean for your health.

Low MCH Levels

An MCH level below 27 picograms/cell is considered abnormally low. Anemia is the most common reason for this.

Low MCH can also be a sign of:

• Autoimmune disease
• Cancer
• Nutritional deficiency (e.g., vitamin B12 or folic acid)
• Internal or external blood loss (e.g., 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 who menstruate may have lower MCH levels than those who don't because of blood loss during a period.

People with low MCH levels may have symptoms including:

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

High MCH Levels

An MCH level above 31 picograms/cell is considered abnormally high. This is most commonly associated with the following conditions:

• Certain types of kidney diseases, including kidney cancer
• Congenital heart defects
• Lung diseases, such as chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis
• Polycythemia vera, a rare blood disease typically caused by a genetic mutation where the bone marrow produces too many red blood cells
• A side effect of certain medications (e.g., anabolic steroids)
• Living in a high-altitude region

People with high MCH levels may have symptoms including:

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

How to Get Your MCH Levels

You may get an MCH test done as part of a CBC ordered for your annual checkup or if your healthcare provider thinks you could have a condition that affects your blood cell counts.

A CBC yields several results, including how many cells there are in the blood, as well as the physical characteristics of the cells, like their size, shape, and content.

Your MCH value typically lines up with your mean corpuscular volume (MCV) level, a measure of the actual size of your red blood cells.

What to Do After MCH Blood Work

The treatment for abnormal MCH levels depends on the cause. While the MCH test can aid in reaching a diagnosis, it cannot confirm one—especially since some conditions can both increase and decrease MCH.

The diagnoses your healthcare provider suspects will guide what happens after receiving a high or low MCH result. They will do more testing to come to a diagnosis, and the tests they may order can range from urine analysis to more blood work to imaging.

In some cases, they may recommend a repeat CBC before moving on to other testing.

Sometimes, MCH levels can get back to normal with modifications such as adding more iron to your diet or avoiding alcohol. Other times, the underlying cause may require medical treatment.

Summary

The MCH blood test is part of a complete blood count (CBC) test. The MCH shows the average amount of hemoglobin in a cell.

A low MCH can be a sign of conditions like anemia and thalassemia. High MCH levels can happen if you have lung or kidney disease.

Your MCH levels are not the only piece of information that points to a certain health condition. Other factors, like your family history and lifestyle, also give your provider key information about your health.