MCH Blood Test: What Your Results Mean

What Is Mean Corpuscular Hemoglobin (MCH)?

As a haematologist, I often explain MCH as the ‘hemoglobin weight per red cell’. It tells us how much haemoglobin, on average, each of your red blood cells carries. Haemoglobin is the iron-rich protein that shuttles oxygen from your lungs to every tissue in your body. When MCH is out of balance, it can hint at underlying conditions ranging from simple iron deficiency to more complex blood disorders.

The test is reported as part of a full blood count (FBC) and is measured in picograms (pg). The LOINC standard code for MCH is 785-6, which ensures consistent reporting across laboratories worldwide.

Why Is MCH Measured?

Doctors check MCH to help classify anaemia — a condition where you don’t have enough healthy red blood cells to carry adequate oxygen. In my clinical practice, I first look at haemoglobin and haematocrit, then turn to MCH and its cousins MCV (mean corpuscular volume) and MCHC (mean corpuscular haemoglobin concentration) to pinpoint the type of anaemia.

MCH is especially useful in distinguishing between microcytic (small cell) and macrocytic (large cell) anaemias. For example, iron deficiency anaemia typically shows a low MCH, while vitamin B12 deficiency often raises MCH.

Normal MCH Reference Ranges

Reference ranges can vary slightly between labs, but the values below are widely accepted for adults and children. Always interpret results alongside your personal health context.

Low MCH (Hypochromia)

A low MCH means each red blood cell contains less haemoglobin than normal. The cells appear pale under the microscope. The most common cause is iron deficiency, often due to blood loss, poor dietary intake, or malabsorption. In my patients, I’ve seen it with heavy menstrual periods, chronic gastrointestinal bleeding, and after bariatric surgery.

Other causes include thalassemia (a genetic haemoglobin disorder), anaemia of chronic disease, and rarely lead poisoning. If your MCH is low, your doctor will check your iron stores (ferritin, serum iron) and possibly perform haemoglobin electrophoresis to rule out thalassemia.

Low MCH Symptoms

Fatigue, pale skin, shortness of breath, dizziness, and brittle nails are common. Many patients describe feeling “washed out” even after a full night’s sleep.

How to Increase MCH

Treatment depends on the root cause. For iron deficiency, I recommend oral iron supplements (ferrous sulphate or ferrous fumarate) and dietary changes — red meat, leafy greens, lentils, and vitamin C to enhance absorption. For thalassemia, iron supplements are usually not helpful and can be harmful; the focus is on managing symptoms.

High MCH (Macrocytosis)

A high MCH indicates that red cells are larger than normal and carry more haemoglobin. This often points to macrocytic anaemia. The main culprits are vitamin B12 deficiency and folate deficiency, both essential for DNA synthesis in red blood cell production.

Other causes include hypothyroidism, liver disease, alcoholism, medications such as methotrexate or azathioprine, and myelodysplastic syndromes. If I see a high MCH in my clinic, I always ask about diet (vegan/vegetarian), alcohol intake, and any use of proton pump inhibitors (which reduce B12 absorption).

High MCH Symptoms

Numbness or tingling in hands and feet, memory problems, glossitis (smooth, red tongue), and fatigue. Neurological symptoms may appear before anaemia develops.

MCH During Pregnancy

Pregnancy increases blood volume, which can dilute haemoglobin, but MCH usually stays stable. Mildly low MCH is common due to iron demands from the growing baby. I advise all pregnant women to take prenatal vitamins with iron and folic acid. If MCH falls significantly, supplement adjustments may be needed.

MCH vs. MCHC: What’s the Difference?

Patients often confuse MCH and MCHC. MCH is the average haemoglobin per red cell; MCHC is the average concentration of haemoglobin in a given volume of red cells. MCHC is more sensitive to conditions like spherocytosis. Both are part of the same storyline, but MCH helps size up the cell’s payload.

When to See Your Doctor

An isolated abnormal MCH without symptoms may be a laboratory artifact or a subtle early sign. However, if you experience persistent fatigue, paleness, or unusual shortness of breath, don’t brush it off. A simple blood test can often provide the answer. In my experience, early detection makes a world of difference — treat the cause, and the MCH usually returns to normal within weeks to months.

Always consult with your healthcare provider for a diagnosis tailored to your health status.