RBC indices are tests that help healthcare professionals measure the size, shape, and quality of red blood cells. Performing these tests can help with a diagnosis, such as identifying the cause of anemia.

Red blood cell (RBC) indices are tests that measure the physical characteristics of a person’s RBCs. RBCs carry oxygen from a person’s lungs to tissues and organs in their body, which they require to function properly. RBCs also help carry carbon dioxide (CO2) back to the lungs and exhale it.

The term indices refers to measurements. Another name for RBC indices is erythrocyte indices. RBC indices measure different qualities of a person’s RBCs and can help diagnose conditions that affect RBCs.

For example, they can help healthcare professionals diagnose the cause, type, and correct treatments of a person’s anemia. Anemia is a health condition that occurs when someone does not have enough healthy RBCs.

A lab technician preparing a blood sample for a RBC indices test-1.Share on Pinterest
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RBC indices are blood tests that measure different characteristics of RBCs. They are part of a complete blood count (CBC). A CBC is a group of tests that healthcare professionals use to measure the parts, amounts, and features of a person’s blood.

RBC indices measure the size, shape, and quality of a person’s RBCs. If more than one of these measures is not within healthy ranges, it may indicate that a person has some type of anemia. This is a condition in which the body does not make enough healthy RBCs.

A person might need RBC indices as part of routine checkups. They also help healthcare professionals diagnose someone with anemia.

Anemia is when a person’s blood produces lower than the typical amount of healthy RBCs. Their RBCs may be misshapen or may not work well, and their body does not then get enough oxygen-rich blood.

A person might have RBC indices if they have symptoms of anemia, including:

More severe anemia may cause chest pain and less tolerance for exercise. People with mild anemia may not have any symptoms.

There are multiple types of anemia with different effects on a person’s RBCs. RBC indices help determine the type of anemia a person has, alongside other tests such as:

  • a person’s:
    • medical history
    • family history
  • a physical exam

During an RBC indices test, a healthcare professional takes a small blood sample from a vein in a person’s arm. The test usually takes less than 5 minutes.

Medical professionals then use an automated blood cell analyzer to detect anemia as part of the CBC. This produces an RBC indices result.

There are four parts of RBC indices:

  • Mean corpuscular volume (MCV): This measures the average volume of a person’s RBCs.
  • Mean corpuscular hemoglobin (MCH): This measures the average amount of hemoglobin in a single RBC. Hemoglobin is a substance in a person’s RBCs that carries oxygen.
  • Mean corpuscular hemoglobin concentration (MCHC): This measures hemoglobin in a person’s RBCs. It also includes calculations to determine the size and volume of their RBCs.
  • Red cell distribution width (RDW): This measures differences in size and volume across a person’s RBCs.

The test produces results for each part of the RBC indices test. Atypical results for each part may include:

  • MCV: Smaller than typical RBCs may mean a person has iron deficiency anemia (IDA). This is the most common form of anemia, where a person does not have enough iron in their body. It may also mean they have thalassemia, an inherited disease that may cause severe anemia. Larger than typical RBCs, known as macrocytic anemia, can indicate liver disease or vitamin B deficiency.
  • MCH: Lower than typical hemoglobin can also indicate a person has IDA. Higher than typical hemoglobin can indicate anemia due to vitamin B deficiency or that a person has high blood cholesterol levels.
  • MCHC: Lower than average hemoglobin can also indicate IDA or thalassemia. Higher than average levels can indicate a person has hemolytic anemia. This is a type of anemia where a person’s red blood cells break down faster than their body makes them. It may also indicate they have hereditary spherocytosis, a rare genetic condition that causes anemia and gallstones.
  • RDW: Differences in the size of a person’s red blood cells may indicate a health problem. However, healthcare professionals cannot diagnose someone with RDW results alone. They combine these results with other types of indices and blood tests to confirm a diagnosis.

The typical range of results for each person can vary according to several factors, such as sex, age, and race.

After RBC indices, healthcare professionals may perform other tests on a person, such as:

  • using a small camera on a tube to check for problems in a person’s:
  • using genetic tests
  • using urine tests

These can be to rule out other conditions, detect any complications from anemia, or confirm anemia.

If a person has anemia, their treatment depends on its cause, how serious it is, and the type of anemia. Treatments may include:

  • medication
  • dietary supplements, such as iron or vitamin B12 supplements
  • blood transfusions
  • blood or bone marrow transplants
  • surgery, if a person has internal bleeding
  • changes to a person’s dietary habits

People with mild anemia may not need treatment.

Red blood cell (RBC) indices are tests that measure the characteristics of RBCs using a blood sample. Healthcare professionals can use these tests to diagnose health conditions, such as anemia.

The results of RBC indices can help healthcare professionals determine which type of anemia a person may have or rule out other conditions. Following a diagnosis, a doctor can then prescribe the correct follow-up testing and treatments.