What Are MCH Levels?
Mean corpuscular hemoglobin, or MCH, is the average amount of hemoglobin in one of your red blood cells. It is not the same as MCHC. That’s your “mean corpuscular hemoglobin concentration.” It’s another measure of hemoglobin, but it takes into account how big or small your red blood cells are. The average size of the cells is mean corpuscular volume (MCV).
If your MCH levels are off, it’s normal to worry. But your doctor will order more tests to find out what’s going on. A lab technician may do a blood smear. That means the technician looks at your blood under a microscope. Your doctor will probably test your blood to see if you have enough vitamin B12, folate, and iron.
MCH that is either low or high can cause concern. But once the doctor determines what’s going on, she can take steps to address the issues. Here’s information to help you understand what’s going to happen when the doctor tells you your MCH is either higher or lower than it should be.
What Are Normal MCH Levels?
Why Test MCH Levels?
The MCH test is part of the complete blood count (CBC). That’s a set of tests that show the health of your blood cells. You may get a CBC as part of your yearly checkup. Or, your doctor may order one if you have symptoms of certain health problems.
The doctor may look closely at MCH -- along with MCV and MCHC -- if you show signs of anemia or certain nutritional deficiencies.
What Is the Normal Range for MCH?
On average, your MCH should be between 27.5 to 33.2 picograms (pg) per cell. Women’s MCH may be lower than men’s because women lose blood when they have a period.
What Do Low MCH Levels Mean?
Your MCH dips below normal when your body doesn’t make enough hemoglobin. One reason for this is microcytic anemia. That means your red blood cells are too small. Extremely low iron levels are usually the cause of this type of anemia.
You may be at risk for iron-deficient anemia if you:
- Bleed a lot during your period
- Have celiac disease or inflammatory bowel disease (Crohn’s or ulcerative colitis)
- Don’t eat enough food with iron (vegans and vegetarians)
- Have peptic ulcer disease
- Bleed from other conditions
- Had gastric bypass surgery
- Are pregnant
- Gave birth recently
- Are healing from a trauma or surgery
Your MCH levels could also be low if your body doesn’t make enough healthy red blood cells -- a condition called thalassemia. The name refers to a group of blood disorders that a person has at birth. You get it from your parents’ genes.
Symptoms of Low MCH
When you have low MCH, your red blood cells carry less oxygen through your body. That’s what makes you feel tired. You may also have:
- Pale or yellow skin
- Trouble breathing
- Chest pain when you are active
- Fast heartbeat
- Weak nails or hair loss
- Tongue problems (soreness or smoothness)
- Strange noises in your ears
- An urge to eat ice or clay
- A hard time focusing
- Leg cramps
Treatment for Low Levels
The treatment depends on what is causing your symptoms. If you have a mild lack of iron, your doctor may ask you to:
- Eat more food with iron
- Take iron pills
- Add vitamin C to your diet (to help you absorb iron)
- Quit drinking black tea (lowers iron absorption)
If you have a serious lack of iron, you may need:
- Intravenous (IV) iron therapy – iron medication infused into a vein
- A blood transfusion – someone else’s blood infused into your vein
You may not need any treatment if you have mild thalassemia. But if your condition is more serious, you may get:
- Blood transfusions
- Iron chelation therapy – medication that you swallow or receive via IV, which you may need if you have high iron from many transfusions
- Folic acid pills
Do not take iron supplements if you don’t have low levels of iron. It could hurt your organs.
What Do High MCH Levels Mean?
Your MCH will reflect your MCV. That means you’ll have more hemoglobin if your red blood cells are larger than normal. Red blood cells can grow too large when you have fewer of them than normal -- a condition called macrocytic anemia. It’s more common if you’re elderly. Lifestyle or genetic factors can also cause it.
You may have high MCH if you have very low vitamin B12 or folate. These are B vitamins that help you make red blood cells. This may happen if:
- Your stomach can’t absorb vitamin B12 (pernicious anemia)
- You have all or part of your stomach removed (gastrectomy)
- You eat a vegan diet (plant foods have little to no B12)
- You have an autoimmune condition
Other causes include:
- Down syndrome
- Myelodysplastic syndrome (a stem cell disorder)
- Liver problems
- Cigarette smoking
Certain medicines may cause your MCV and MCH levels to go up, including these types:
You may not have a health problem causing your high MCH. Let your doctor know if you have a family history of increased MCV or MCH. If doctors don’t find a cause, they may want to recheck your levels every six months.
Symptoms of High Levels
You may not feel bad if your MCH is high. But it may be a sign that your red blood cells aren’t dividing the right way. This may cause anemia because you end up with fewer red blood cells. You could have symptoms similar to low MCH. The most common one is tiredness.
If you don’t have enough vitamin B12, you might have:
- Numbness or “pins and needles” in your hands and feet
- Trouble with your balance
- Muscle weakness
- Confusion, memory loss
- Depression, mood problems
- Smooth, red, or swollen tongue
- Nausea, throwing up
- Stomach problems, diarrhea
- No appetite, weight loss
Treatment for High Levels
Like low levels, your care depends on the cause of your symptoms. When your doctor finds out why you have high MCH, you may need:
- Vitamin B12 shots or pills
- A different type or dose of medicine
- Folic acid pills
If you have low B12, you may feel better within a few days of treatment. Make sure to check in with your doctor until your levels are back to normal. Too little B12 for too long can raise your risk of stomach cancer. It could also damage your:
- Digestive tract
Outlook for High or Low MCH Levels
Your doctor can help you monitor or treat whatever is causing your high or low MCH levels. Dietary or lifestyle changes might help. Or you could need a more serious treatment to get well. Your health care team can help find the right way to help you stay healthy.
Sarma, P. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition, Butterworths, 1990.
Cleveland Clinic: “Executive Health Reference Guide.”
American Society of Hematology: “Blood Basics,” “Iron-Deficiency Anemia.”
American Association for Clinical Chemistry, Lab Tests Online: “Red Cell Indices,” “Complete Blood Count (CBC).”
Dean, L. Blood Groups and Red Cell Antigens, National Center for Biotechnology Information, 2005.
Chaudhry, H., Kasarla, M. Microcytic Hypochromic Anemia, StatPearls Publishing, 2019.
National Heart, Lung, and Blood Institute: “Thalassemias,” “Iron-Deficiency Anemia,” “Pernicious Anemia.”
University of Rochester Medical Center: “Iron Deficiency After Gastric Bypass Surgery,” “Vitamin B-12 Deficiency Anemia,” “Folate-Deficiency Anemia.”
CDC: “Thalassemia: Complications and Treatment.”
Clinical Medicine & Research: “Megaloblastic Anemia and Other Causes of Macrocytosis.”
Journal of General and Family Medicine: “Diagnosis and treatment of macrocytic anemias in adults.”
National Down Syndrome Society: “Blood Diseases & Down Syndrome.”
Medical Archives -- Journal of The Academy of Medical Sciences in Bosnia and Herzegovina: “Effect of Cigarette Smoking on Haematological Parameters in Healthy Population.”
Blood: “The Significance of Unexplained Macrocytosis.”
Hariz, A., Bhattacharya, P. Megaloblastic Anemia, StatPearls Publishing, 2019.