An RBC count is a blood test that measures how many red blood cells (RBCs) you have.
RBCs contain hemoglobin, which carries oxygen. How much oxygen your body tissues get depends on how many RBCs you have and how well they work.
Erythrocyte count; Red blood cell count; Anemia - RBC count
How the Test is Performed
A blood sample is needed.
How to Prepare for the Test
No special preparation is necessary.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
The RBC count is almost always part of a complete blood count (CBC) test.
The test can help diagnose different kinds of anemia (low number of RBCs) and other conditions affecting red blood cells.
Other conditions that may require an RBC count are:
Normal RBC ranges are:
The ranges above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.
What Abnormal Results Mean
Higher than normal numbers of RBCs may be due to:
Your RBC count will increase for several weeks when you are in a higher altitude.
Drugs that can increase the RBC count include:
Lower-than-normal numbers of RBCs may be due to:
Drugs that can decrease the RBC count include:
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
Bunn HF. Approach to the anemias. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 158.
Chernecky CC, Berger BJ. Red blood cell (RBC) – blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier; 2013:961-962.
Review Date: 2/18/2018
Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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