Red Blood Cell (RBC) Count
Reviewed
An RBC count measures the number of red blood cells in your blood. It is almost always part of a complete blood count (CBC) and helps diagnose red blood cell disorders such as anemia.
Preparation and collection
No special preparations needed.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- The RBC count is often the first sign of an illness, but it is not diagnostic by itself.
- Your provider will consider your symptoms, medical history, and other test results to interpret your RBC count.
What to do next
If your results were low or high, you may need more tests such as a reticulocyte count, iron tests, or vitamin B tests to help your provider make a diagnosis. Talk to your health care provider if you have questions about your results.
Evidence source
U.S. National Library of Medicine: Red Blood Cell (RBC) Count