Red Blood Cell Indices: Types, Uses, Results

What MCHC, MCV, MCH, and RDW Mean and Reveal

One of the most common blood tests is the red blood cell (RBC) indices. It is a component of a larger battery of tests known as the complete blood count (CBC). The information offered by the RBC indices can provide valuable insights about your current health, possible diseases you may have, or how well you are responding to treatments.

Although it is easy to be confused by all of the numbers and abbreviations on the report—MCHC, MCV, MCH, and RDW—it is your interest to have an idea of what they mean. Doing so can help you participate more actively in your care and make informed choices.

This article breaks down the various tests that make up the RBC indices, including what high and low test values mean.

Red and white blood cells in the bloodstream.
Science Photo Library / SCIEPRO / Getty Images

What Is a Complete Blood Count?

The RBC indices are part of the larger complete blood count (CBC). The CBC is a battery of blood tests ordered by your healthcare provider to evaluate the composition and quality of the blood cells in your body.

This not only includes white blood cells (leukocytes) that help fight infection and platelets (thrombocytes) that clot blood but also red blood cells (erythrocytes) that transport oxygen throughout the body

The complete blood count is so named because that is exactly what it does: count cells. The values are reported in different ways, sometimes by the actual number of cells in a sample of blood and, at other times, by the proportion of one group of cells to another group of cells.

In their totality, these values can tell a healthcare provider a lot about the state of your health.

How to Read a Blood Test Report

The first step in learning how to read any blood test report is to understand the reference ranges of values. This is the set of values between which a blood test result is considered normal.

Simply put:

  • Anything above the reference range of values is considered high (and is usually marked on the report as "High" or "H").
  • Anything below the reference range of values is considered low (and is usually marked on the report as "Low" or "L").
  • Anything between the high and low values is normal.

It's important to note that high and low values are "abnormal" but, on their own, don't necessarily mean anything until they are compared with other blood, lab, or imaging tests.

The reference range is based on the expected values within a given population. As such, the values can vary from one population to the next or sometimes even from one lab to the next.

By way of example, hemoglobin values (used in part to detect anemia) are invariably higher at high altitudes than they are at sea level. Therefore, not only does the reference range for hemoglobin differ but so, too, does the diagnostic definition of anemia.

Normal values can also sometimes differ by age, biological sex, and even race.

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This video has been medically reviewed by Chris Vincent, MD.

Red Blood Cell (RBC) Count

The red blood cell (RBC) count is the general starting point of any evaluation of red blood cells. As per its name, it simply counts the number of red blood cells in a sample of blood. The RBC count is measured in millions of cells per microliter (one-millionth of a liter), or cells/mcL.

A normal RBC count depends on age and sex:

  • Women: 4.2 - 5.4 million cells/mcL
  • Men: 4.7 - 6.1 million cells/mcL
  • Children: 4.1 - 5.5 million cell/mcL

A low and high RBC count can mean any number of things, both benign and severe.

Possible Causes of a Low and High RBC Count

Low RBC
High RBC

Red Blood Cell (RBC) Indices

Along with the RBC count, the RBC indices provide information about the quality of your red blood cells. The RBC indices look at specific components or characteristics of red blood cells, including their size and proportion.

The RBC indices also look at a protein in red blood cells called hemoglobin that is responsible for transporting oxygen from the lungs to the rest of the body. Hemoglobin is also the protein that gives red blood cells their red color.

The RBC indices are comprised of four different components known as the mean corpuscular hemoglobin concentration (MCHC), the mean corpuscular volume (MCV), the mean corpuscular hemoglobin (MCH), and the red cell distribution width (RDW).

Mean Corpuscular Hemoglobin Concentration (MCHC)

The mean corpuscular hemoglobin concentration (MDHC) is the average concentration of hemoglobin in a sample of red blood cells. A corpuscle is simply a term used to describe a living cell, particularly red and white blood cells.

The MCHC basically tells whether you have more or less hemoglobin than what would be expected. The MCHC is measured in grams of hemoglobin per deciliter (one-thousandths of a liter) of blood, or g/dL.

A normal reference range for MCHC is between 32 and 36 g/dL in adults.

Low and high MCHC can mean any number of different things:

Possible Causes of a Low or High MCHC

Low MCHC

Mean Corpuscular Volume (MCV)

Mean corpuscular volume (MCV) measures the average volume of red blood cells. Any increase or decrease in the normal volume/size of a red blood cell can affect its ability to transport oxygen, leading to anemia. The MCV is measured in femtoliters (one thousand trillionths of a liter) per cell, or fL/cell.

A normal reference range for MCV is between 80 and 96 fL/cell.

Low and high MCV values can mean any number of things:

Possible Causes of a Low or High MCV

Low MCV
High MCV
  • Hemolytic anemia

  • Vitamin B12 deficiency

  • Folate deficiency

  • Liver disease

  • Alcoholism

  • Hypothyroidism

  • Leukemia

  • Chemotherapy

It's important to note that a person can have anemia and have a normal MCV. This is called normocytic anemia. Causes may include:

Mean Corpuscular Hemoglobin (MCH)

Mean corpuscular hemoglobin (MCH) is the average amount of hemoglobin per red blood cell in a sample of blood. MCH is measured in picograms (one trillionth of a gram) per cell, or pg/cell.

The MCH value directly parallels the MCV value, and, for this reason, some healthcare providers find the test redundant. As such, if the size of the red blood cells is large (as measured by the MCV), the amount of hemoglobin per red blood cell will be high (as measured by the MCH), and vice versa.

A normal reference range for MCH is between 27 and 32 pg/cell.

The possible causes of low and high MCH tend to echo those of a low and high MCHC.

Red Cell Distribution Width (RCW)

Red cell distribution width (RDW) is a test that assesses the variability in the size of the red blood cells. A normal RDW would mean that your red blood cells are all similar in size, whereas a higher RDW means that there is more variability in the size of the red blood cells.

RDW values are described in percentages (%). They are calculated by dividing the mean reference range value of MCV by the actual MCV value and multiplying it by 100%.

A normal reference range for RDW is 11.5% to 14.5%.

A low RDW means that red blood cells are not very different in size from typical measurements. A high RDW means they differ in size more significantly, which can indicate the body is having trouble producing enough red blood cells.

The interpretation of the RDW differs from the other blood tests in that it varies based on its relationship to the MCV. In short, the sizes and variability of sizes of red blood cells can indicate vastly different things.

Here are just a handful of examples:

RDW Result MCV Result Possible Causes
High High - Vitamin B12 deficiency
- Folate deficiency
- Hemolytic anemia
- Coronary artery disease
- Peripheral artery disease
- Myelodysplastic syndromes
- Cold agglutinin disease
High Low - Iron deficiency anemia
- Iron malabsorption
- Sickle cell disease
High Normal - Iron deficiency anemia
- Chronic internal bleeding
- Thalassemia
Normal High - Aplastic anemia
- Alcoholism
- Viral hepatitis
- Liver cirrhosis
- Liver cancer
Normal Low - Anemia of chronic disease
- Thalassemia
- Sickle cell anemia

Summary

A red blood cell (RBC) indices are a battery of tests that evaluates measurable characteristics of red blood cells, including their size and the concentration of hemoglobin in them. The tests include the mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and red cell distribution width (RDW).

The test values can point a healthcare provider in the direction of the possible causes when compared to each other or to other blood, lab, or imaging test results.

A Word From Verywell

Red blood cell (RBC) indices are an important group of tests commonly used to diagnose and monitor diseases. The reference range of values for these tests is generally consistent, although there may be variations between certain tests depending on which lab you go to.

If you are being treated for a chronic medical condition and need regular blood tests, make every effort to go to the same lab every time to ensure consistency in results. This can help avoid the misinterpretation if one lab's reference range is different from another.

Frequently Asked Questions

  • What diseases can a CBC test detect?

    A complete blood count (CBB) can help diagnose or rule out medical conditions based on which values are either high or low. With that said, the test cannot diagnose any medical condition but only point a healthcare provider in the direction of possible causes.

  • What does it mean when your MCV and MCH are high?

    The results of a mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) tend to follow one another—that is, if one is high, the other will be, too. That is because when the cells are bigger, they have more hemoglobin in them. High MCV levels can be caused by vitamin deficiencies, liver problems, alcohol use, and some medications.

  • What cancers cause high MCH levels?

    Myelodysplastic syndromes are a type of bone marrow cancer. These cancers can cause a high mean corpuscular hemoglobin (MCH). Even so, a high MCH can be caused by many things and cancer is generally a less likely cause.

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12 Sources
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