Red Blood Cell (RBC) Count

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

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. STOCK4B/STOCK4B/Getty Images


A red blood cell (RBC) count is a type of blood test that can provide information about how many red blood cells are in a person's blood. Knowing why your doctor ordered an RBC count and what the results of your RBC count mean is important in understanding how it relates to your health. Physicians will look for a normal RBC count result, but when the level is out of a normal range, may find it necessary to search for reasons why the level may be too high or too low.

The RBC count test might sometimes be done as one piece of a more comprehensive blood test, which is called a complete blood cell (CBC) count. The RBC count is typically not used alone to diagnose a condition or a disease. In some cases, the RBC count may be less helpful to a physician than other blood tests such as a hematocrit or a hemoglobin test. 

An RBC count that is higher or lower than expected could result from one or more of 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 in the process of diagnosing a disease or condition. This is especially true in the case of a heme disorder, which is one of several conditions that cause an irregularity in producing heme. Heme is an important component of blood that is composed of iron and is the substance that gives blood its red color.



An RBC count is the number of red blood cells per a particular volume of blood. This number may be reported in millions of cells in a microliter of blood or in millions of cells in a liter of blood. Labs that process blood draws may use other units to report the number of RBCs and will also have variations in what is considered a normal RBC count range.

The table below contains just one example of a normal range of RBCs. A "normal" RBC count may also vary slightly from person to person, so the reference range is just that; it's not a hard and fast rule to go by. 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 Done With the RBC Count?

Levels of RBCs that are out of the normal range (either an RBC that's considered too high or too low) can be an indication that certain diseases or conditions are present. However, it's good to keep in mind that while it is useful information, the RBC count is not a test that can be used solely to diagnose a disease or condition. Polycythemia (an increase in the number of RBCs) or erythrocytosis (an increase in the number RBCs or a decrease in the volume of plasma) are terms that may be used to describe an elevated RBC count.

A higher than typical RBC count may be associated with:

A lower than typical RBC count may be associated with:

How an RB​C Count Relates to IBD

People with IBD may lose blood through the inflammation and ulcers in their intestines. This will cause a lowered RBC count.

In some cases, this will be expected and the reason will be understood. However, people with IBD may also have a low RBC count because their bodies are not making enough RBCs. People with IBD should work closely with a gastroenterologist and other physicians to understand the reasons why an RBC count might be out of the normal range, and how to correct it.

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