What Is Mean Corpuscular Hemoglobin Concentration (MCHC)? (2024)

Mean corpuscular hemoglobin concentration (MCHC) is a blood test that calculates the average concentration of hemoglobin in red blood cells in relation to their volume.

Hemoglobin is an iron-rich protein in red blood cells that carries oxygen to tissues (and gives blood its red color). Measuring hemoglobin through an MCHC test can help determine whether you have anemia (a condition where you have either too few red blood cells or too little hemoglobin).

Both high or low MCHC values may indicate anemia. It is only when the MCHC results are compared with other blood test results that healthcare providers can narrow the possible causes, which may include iron deficiency, blood disorders, or even cancer.

This article explains the value of the MCHC test, including what high and low values mean and the various factors that can throw readings off. It also describes other blood tests commonly used with the MCHC to diagnose disease.

MCHC Results and What They Mean

An MCHC blood test is part of a panel of tests called the red blood cell (RBC) indices. These tests evaluate the composition, size, and volume of red blood cells. The RBC indices, in turn, are part of a larger panel of blood tests called the complete blood count (CBC).

The MCHC is measured in values of grams per liter (g/dL). The reference range of values for the MCHC test is 32 to 36 g/dL. Anything between these values is normal.

Results that fall outside of the reference range are interpreted as follows:

• A low MCHC indicates a low concentration of hemoglobin in your red blood cells, often as a result of iron deficiency or diseases that affect hemoglobin production.
• A high MCHC indicates a higher hemoglobin concentration in red blood cells than what is normal. This may also be caused by different types of anemia.
  

What Causes a Low MCHC?

A low MCHC is typically a sign of iron deficiency. As iron is a major component of hemoglobin, a loss of iron can cause hemoglobin concentrations to drop, leading to iron deficiency anemia.

Other possible for a low MCHC include:

• Lead poisoning: Lead blocks enzymes needed to synthesize hemoglobin, causing hemoglobin numbers to drop,
• Thalassemias: This is a group of blood disorders that affect the normal production of hemoglobin and red blood cells.
• Sideroblastic anemia: This is a form of anemia associated with vitamin B6 deficiency that interferes with the abnormal utilization of iron.
• Anemia of chronic disease: This is a form of anemia in which the body has ample iron stores but the body is unable to use it due to any number of chronic diseases, like tuberculosis and HIV.

A low MCHC without anemia may also indicate iron deficiency before anemia develops.

What Causes a High MCHC?

A high MCHC may be due to different types of anemia. Chief among these is hemolytic nemia. This is when red blood cells die (or are killed faster) than they are produced. When this happens, the hemoglobin concentrations may be high even as the red blood cell counts drop.

Causes for this include:

• Autoimmune disorders: These include systemic (whole-body) autoimmune diseases like lupusthat can kill red blood cells with inflammation.
• Liver disease: Because the liver is tasked with breaking down red blood cells, diseases like cirrhosis can speed the process, reducing red blood cell counts. Alcohol abuse can do the same.
• Sickle cell disease: This is a genetic disorder that causes abnormally shaped red blood cells, leading to sickle cell anemia.
• Hypothyroidism: Low thyroid function slows the production of red blood cells. This is especially true with the autoimmune form of hypothyroidism, called Hashimoto's disease.
• Lymphoma: This blood cancer produces antibodies that target red blood cells, triggering a chain reaction that causes them to rupture and die.
• Cold agglutinin disease (CAD): This is a rare autoimmune disorder in which the body's immune system attacks red blood cells.
• Vitamin B12 deficiency: Vitamin B12 is needed to produce red blood cells, and the depletion of this vitamin can lead to pernicious anemia.

How MCHC Values Are Calculated

Two different formulas can be used to calculate the MCHC, the value of which is reported as grams per deciliter (g/dL). Using two methods can improve the accuracy of the reading.

Method One

The primary method of calculating the MCHC is based on the result of two different blood tests:

• Hemoglobin (Hbg): This measures the amount of hemoglobin in a sample of blood, reported as grams per deciliter (g/dL)
• Hematocrit (HCT): This is the proportion of whole blood composed of red blood cells, reported as a percentage (%).

For this method, the MCHC is calculated by multiplying the Hgb value times 10 and then dividing that number by the HCT, as follows:

Method Two

The secondary method looks at other aspects of red blood cells and hemoglobin, specifically their size and mass. The formula is based on the results of the following tests:

• Mean corpuscular hemoglobin (MCH): This measures the average mass of hemoglobin in each red blood cell, reported in picograms per cell (pg/cell),
• Mean corpuscular value (MCV): This measures the actual size of your red blood cells, reported in femtoliters (fl).

For this method, the MCHC is calculated by dividing the MCH value by the MCV value as follows::

Causes of Inaccurate MCHC Results

The MCHC is not a direct measurement. Rather, it is an estimate based on measurable values like hemoglobin and hematocrit, both of which are vulnerable to transient changes. Because of this, any condition that can throw off these values can throw off the MCHC as well.

Examples include:

• Blood transfusions: Getting a transfusion can temporarily increase your Hgb and HCT, particularly if you are given a packed red blood cell (PRBC) transfusion.
• Plasma transfusions: A plasma transfusion without any circulating blood cells can cause the dilution of red blood cells, causing a falsely low Hgb count.
• Combined anemia: This is when you have one type of anemia that traditionally causes a low MCHV (like iron deficiency anemia) and another that traditionally causes a high MCHC (like sickle cell anemia). Having both can throw off the MCHC reading.
  
• Hyperlipidemia: High cholesterol can mistakenly cause a high Hgb count. This is because cholesterol binds to hemoglobin released from red blood cells after they die. The higher the cholesterol count, the higher the Hgb count.

Because different factors can throw off MCHC results, labs will often use both formulas—Hgb/HCT and MCH/MCV—to get a more reliable value.

Related Blood Tests

In addition to MCHC, there are other tests and procedures used to diagnose the type and cause of anemia, including:

• Red cell distribution width (RDW): This describes the variation in the size of red blood cells. A high RDW is linked tovitamin B12deficiency,sickle cell disease,andcold agglutinin disease.
• Peripheral blood smear: This is the examination of blood cells under the microscope. which readily spot abnormalities like sickle cell disease.
• Iron studies: This can differentiate iron deficiency anemia from other anemias.
• Vitamin B12: Low levels of vitamin B12 can help support a diagnosis of pernicious anemia.
• Bone marrow biopsy: A sample of bone marrow can be studied to determine the cause of anemia, including conditions like lymphoma or an iron storage disease.
  

Summary

Mean corpuscular hemoglobin concentration (MCHC) is a measure of the concentration of hemoglobin in red blood cells. A normal MCHC is typically between 32 g/dL to 36 g/dL. A higher or lower MCHC may indicate different types of anemia. Other tests may be used to help narrow the causes.