Red Blood Cell (RBC) Indices
Reviewed
Also called: Erythrocyte indices, MCV, MCH, MCHC, RDW
Red blood cell (RBC) indices measure your red blood cells' size, shape, and quality. They are part of a complete blood count (CBC) and are used to help diagnose different types of anemia. A health care professional will take a blood sample from a vein in your arm. There is very little risk to having a blood test; you may have slight pain or bruising at the needle site, but most symptoms go away quickly.
Specimen: blood sample from a vein in your arm
Why this test may be ordered
- As part of a routine checkup
- If you have symptoms of anemia such as shortness of breath, weakness, fatigue, headache, dizziness, arrhythmia, pale skin, or cold hands and feet
Preparation and collection
No special preparation is needed.
A blood sample is drawn from a vein in your arm using a small needle. The procedure usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
You will get results for each of the four indices: mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and red cell distribution width (RDW). Your healthcare provider will interpret your results based on your symptoms, medical history, and other test results.
- All RBC indices within normal range: Your red blood cells are normal in size, shape, and hemoglobin content. This suggests you do not have anemia related to these measurements. However, your healthcare provider will consider your overall health and other test results. Limitation: Normal indices do not rule out all types of anemia or other blood disorders. Your provider may need additional tests. Next step: Routine follow-up as recommended by your healthcare provider.
- One or more RBC indices outside normal range: Abnormal results may indicate a type of anemia. For example: - Low MCV (smaller red blood cells) may suggest iron deficiency anemia or thalassemia. - High MCV (larger red blood cells) may suggest anemia caused by vitamin B deficiency or liver disease. - Low MCH (less hemoglobin per cell) may suggest iron deficiency anemia. - High MCH (more hemoglobin per cell) may suggest anemia caused by vitamin B deficiency. - Low MCHC (less concentrated hemoglobin) may suggest iron deficiency anemia or thalassemia. - High MCHC (more concentrated hemoglobin) may suggest hemolytic anemia or hereditary spherocytosis. - Abnormal RDW (variation in red blood cell size) is not enough for a diagnosis on its own; it is combined with other indices and tests to help confirm a diagnosis. Limitation: These results alone do not confirm a specific condition. Your healthcare provider will consider your symptoms, medical history, and other blood tests to make a diagnosis. Next step: Discuss your results with your healthcare provider. Further testing may be needed to determine the cause and appropriate management.
- Reference ranges and units are not provided in the source; interpretation should be done by your healthcare professional.
- RDW results alone are not diagnostic and must be combined with other indices and tests.
What to do next
Talk to your health care provider if you have questions about your results. Your provider will consider your symptoms, medical history, and the results of other blood tests to understand your results.
- What do my RBC index results mean for my health?
- Do I need any additional tests?
- What type of anemia might I have based on these results?
- What are the next steps for treatment or monitoring?
Evidence source
U.S. National Library of Medicine: Red Blood Cell (RBC) Indices