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Red Blood Cell (RBC) Count

An RBC Count Is Often Used In Conjunction With Hemoglobin And Hematocrit Tests


Updated August 17, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Test tubes for blood samples

A red blood cell count can tell a physician if there is blood loss, or if there is anything wrong with the blood cells in the body.

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What Is A Red Blood Cell (RBC) Count?

A red blood cell (RBC) count is a blood test that can provide information about how many red blood cells are in a person's blood. This test might be done as one component of a complete blood cell (CBC) count. The RBC count is typically not used alone, and may be less helpful to a physician than other blood tests such as a hematocrit and a hemoglobin test.

An RBC count that is higher or lower than expected could result from several different diseases or conditions. This test is not specific enough to diagnose any particular disease, but instead is just one marker that a physician may use, especially in the case of a heme disorder. Heme is an important component of blood that is composed of iron and is gives blood its red color. 

Reference Ranges For An RBC Count

An RBC count is the number of red blood cells per volume of blood, and may be reported in millions of cells in a microliter or blood or millions of cells in a liter of blood. Labs may use other units to report the number of RBCs, and will also have variations in what is considered a normal range. The table below contains an example of a normal range of RBCs. A "normal" RBC count may also vary slightly from person to person. Check with your physician if you have questions regarding your RBC count and what it could mean for your health.

 Example Red Blood Cell (RBC) Count Reference Ranges
 Approximate Range for Women  4.2 to 5.4 million/mcL
 Approximate Range for Men  4.7 to 6.1 million/mcL
 Approximate Range for Children  4.6 to 4.8 million/mcL
 Expressed in million red cells per microliter (mcL) of blood  






What Is The RBC Count Used For?

Levels of RBCs out of the normal range (either higher or lower) can be an indication of certain conditions, although this test alone can not be used to diagnose. Polycythemia or erythrocytosis are terms that may be used to describe an elevated RBC count.

A higher than typical RBC count may be associated with:

  • Congenital heart disease
  • Cor pulmonale 
  • Dehydration (such as from severe diarrhea)
  • Excess RBC production (polycythemia vera)
  • Obstructive lung disease 
  • Pulmonary fibrosis

A lower than typical RBC count may be associated with:

See also -- Video: What Your Red Blood Cell Count Means

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