What is the MCHC Blood Test?
A mean corpuscular hemoglobin concentration (MCHC) blood test measures the amount of a protein called hemoglobin in your red blood cells. It’s one of many measurements included in a complete blood count (CBC) test.
"A CBC is far and away the most common blood test that (doctors) order,” says Patrick Gallagher, MD, professor of pediatrics at Ohio State University. It’s a good idea to have a CBC during your annual physical because it helps your doctor spot blood disorders and other issues.
MCHC is one of several calculations, or indices, in the CBC that help doctors understand the size, shape, and health of your red blood cells (RBCs).
Specifically, MCHC equals the amount of hemoglobin in your RBCs divided by the percentage of your blood that’s made up of red cells. Doctors call this percentage “hematocrit.”
Hemoglobin is a protein in red blood cells that’s rich in iron.It carries oxygen to every cell in your body and moves carbon dioxide out to your lungs so you can exhale it.
What does an MCHC blood test measure?
An MCHC blood test measures the average concentration of hemoglobin in a certain red cell volume. Red cell volume is a measurement of the size of your RBCs and how much they can hold.
"The MCHC is a general assessment of the iron content of the red cells and the oxygen-carrying capacity of red cells," says Gallagher, director of the Center for Perinatal Research in the Abigail Wexner Research Institute at Nationwide Children's Hospital in Columbus, Ohio.
Your body needs iron to make hemoglobin, so having too little (or too much) hemoglobin in your red cells can be a sign of anemia or other problems.
MCHC vs. MCH blood test
Mean corpuscular hemoglobin (MCH) and MCHC are different measurements, though they’re both part of a CBC and help give your doctor insight into your red blood cells.
Your MCH level is the average amount of hemoglobin in a single blood cell. But your MCHC level is the average concentration of hemoglobin in a given volume of red cells.
MCH “does not take into account red cell volume, whereas MCHC does," said Jahnavi Gollamudi, MD, an assistant professor at the University of Cincinnati College of Medicine.
Reasons to Get an MCHC Blood Test
A complete blood count routinely includes an MCHC blood test. Your doctor might pay closer attention to your MCHC if they suspect you have certain conditions, such as:
Anemia
Anemia is when you don’t have enough healthy red blood cells or hemoglobin. You might feel weak, tired, or short of breath when you exercise. There are many types of anemia and they have different causes.
If your doctor thinks you may be anemic, they might order a CBC and check your MCHC levels.
For example, with an inherited type of anemia called hereditary spherocytosis, RBCs break down too quickly and lose their membranes. This causes them to change from doughnut-shaped to sphere-shaped. The amount of hemoglobin hasn’t changed, but the red cells have gotten smaller because they’ve lost their membranes. This leads to a higher concentration of hemoglobin and a high MCHC.
With sideroblastic anemia, your body can't use iron well enough to make normal RBCs. As a result, “you could have red cells that are normal and others that are very small and lack hemoglobin,” Gallagher says. This can affect your MCHC.
Some chronic diseases can cause anemia. For instance, you could become anemic if you have kidney disease, rheumatoid arthritis, or lupus. These conditions can cause chronic inflammation, which interferes with the body's ability to use iron, even if your iron stores are OK. These types of anemia can also cause changes in your MCHC.
Beta thalassemia
Beta thalassemia is an inherited blood disorder. When you have it, your body makes less hemoglobin than normal. This disorder can cause problems with beta-globin, a protein that's part of hemoglobin. You could have low MCHC as a result.
Lead poisoning
When you have lead poisoning, the lead interferes with your body's ability to make hemoglobin. This can lower your MCHC.
Celiac disease or inflammatory bowel disease
You could also need an MCHC blood test if you have celiac disease or inflammatory bowel disease (IBD). These diseases can cause inflammation of your intestinal walls, especially in the small intestine. That interferes with your body’s ability to absorb iron, lowering your MCHC.
Sickle cell disease
You may have a high or low MCHC if you have sickle cell disease. The effects on your MCHC depend on what caused your sickle cell disease, Gallagher says.
What to Expect
An MCHC is usually part of a complete blood count, which you might get routinely as part ofa physical. You probably won't need to do anything special to prepare.If your doctor ordered different tests as part of your CBC, you may need to fast beforehand.
During the test, your provider will use a small needle to take a blood sample from a vein in your arm. You may feel a slight pinch when the needle goes in. Afterward, you could have a small bruise or mild pain where the blood was drawn. The blood draw should take five minutes or less.
Your doctor's office will then send the blood sample to a lab for testing.
Understanding Your MCHC Blood Test Results
Your MCHC will be calculated using an automated hematology analyzer, Gollamudi says. This is a machine that can quickly analyze blood. It will show if your MCHC is above or below what's considered normal.
Average MCHC
An MCHC blood test between 32-36 grams per deciliter (g/dL) is considered normal. Depending on where you have your test done, and what type of technology they use, the numbers could differ slightly.
“For some labs, their normal range might be 31.5 to 35.5,” Gallagher says.
Low MCHC
An MCHC below 32 grams per deciliter (g/dL) is considered low. This might be a sign of anemia or low red blood cell production, celiac disease, or IBD. Your MCHC might also be low if you’re having chemo or radiation treatments.
High MCHC
An MCHC above 36 grams per deciliter (g/dL) is considered high.
“A high MCHC is pretty uncommon, and that's seen in some red blood cell disorders,” Gallagher says. For instance, it can be caused by sickle cell disease or hereditary spherocytosis.
Takeaways
A mean corpuscular hemoglobin concentration (MCHC) blood test measures the concentration of hemoglobin in your red blood cells. It’s usually included in a complete blood count, a blood test that's often part of an annual physical. Your MCHC test results can show how much iron is in your red cells and how well the cells are able to carry oxygen. Too much or too little hemoglobin can be a sign of anemia or other health problems.
MCHC Blood Test FAQs
What level of MCH is concerning?
An MCHC blood test between 32-36 grams per deciliter (g/dL) is considered normal. Results below or above this range could be abnormal, but don't necessarily indicate there's a problem. Your doctor can explain your CBC results if you’re concerned about the findings.
What cancers are associated with low MCHC?
Some blood cancers are associated with low MCHC. “Any cancer that affects bone marrow and decreases red blood cell production can affect it,” Gollamudi says.
Should I worry if my MCH is low?
If your MCH is low, you could have anemia. That's not necessarily serious, though it sometimes can be. “The most common cause of a low MCH and/or a low MCHC is iron deficiency,” Gallagher says.
Can dehydration affect MCHC?
If you're very dehydrated, you could have an elevated MCHC. In that case, you’d need to be given fluids.
