Red Blood Cell (RBC) Count
Reviewed
Also called: Erythrocyte count, Red count
A red blood cell (RBC) count measures the number of red blood cells, also known as erythrocytes, in your blood.
Specimen: Blood (from a vein in your arm)
Why this test may be ordered
- As part of a routine checkup (CBC)
- To monitor treatment that may affect blood cell counts (e.g., chemotherapy)
- To monitor health conditions such as chronic kidney disease
- If you have symptoms of a low or high red blood cell count
Preparation and collection
You don't need any special preparations for a red blood cell (RBC) count.
A health care professional will take a blood sample from a vein in your arm, using a small needle. This usually takes less than five minutes.
There is very little risk to having a blood test. There may be slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
Your results will show whether you have a normal red blood cell count or a count that is too low or too high.
- Low RBC count: Conditions that may cause a low red blood cell count can include: Anemia, Leukemia, a type of blood cancer, Malnutrition, a condition in which your body does not get the calories, vitamins, and/or minerals needed for good health, Multiple myeloma, a cancer of the bone marrow, Kidney failure, Blood loss from injury or other problems, Alcohol use disorder (AUD), Pregnancy Limitation: Your provider will consider your symptoms, medical history, and the results of other blood tests to understand your red blood cell count results. Next step: If results showed you had a low or a high red blood cell count, you may need more tests to help your provider make a diagnosis.
- High RBC count: Conditions that may cause a high red blood cell count can include: Dehydration, Heart disease, Polycythemia vera, a disease which causes your bone marrow to make too many red blood cells, Scarring of the lungs, often due to cigarette smoking, Lung disease, Kidney cancer, Sleep apnea, a disorder that causes you to repeatedly stop breathing during sleep Limitation: Misuse of certain drugs for athletic performance (such as anabolic steroids) and living at a high altitude can also cause a high red blood cell count. Next step: If results showed you had a low or a high red blood cell count, you may need more tests to help your provider make a diagnosis.
- 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
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 red blood cell count results.
- What do my RBC count results mean in my specific situation?
- Do I need any follow-up tests based on my RBC count?
- What symptoms should I watch for?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Red Blood Cell (RBC) Count