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Normal RBC (Red Blood Cell) count in the blood

Blood test
Normal RBC (Red Blood Cell) count in the blood
Last update: 02/12/2020

What is the normal count of RBC in the blood?

RBC count ranges (Red Blood Cells or erythrocytes) depend on gender and age according to the following table:

  • Adult men: 4.5 – 6.2 million/µl (microliter)
  • Adult women: 4 - 5.5 million/µl (microliter)
  • Boys from 15 to 17 years old: 4.3 – 5.7 million/µl (microliter)
  • Girls from 15 to 17 years old: 3.8 – 5 million/µl (microliter)
  • Children from 11 to 14 years old: 4.1 – 5.3 million/µl (microliter)
  • Children from 6 to 10 years old: 4.1 – 5.2 million/µl (microliter)
  • Children from 3 to 5 years old: 4.0 – 5.1 million/µl (microliter)
  • Children of 2 years old: 3.8 – 5 million/µl (microliter)
  • Babies from 6 months old to 2 years old: 3.9 – 5.1 million/µl (microliter)
  • Babies from 8 weeks old to 5 months old: 3.4 – 4.8 million/µl (microliter)
  • Babies from 5 weeks old to 7 weeks old: 2.9 – 4.2 million/µl (microliter)
  • Babies from 2 weeks old to 4 weeks old: 3.1 – 4.8 million/µl (microliter)
  • Newborns (up to 14 days old): 4.1 – 5.7 million/µl (microliter)

Why normal ranges can differ across different labs?

Each laboratory must establish its own normal ranges for RBC count in the blood. These ranges depend on the makeup of the local population, the technologies used and the accuracy of the measurement. There may be also slight differences in the normal levels, according to age, gender, race or ethnic origin, geographic region, diet, type of sample and other relevant status.

Your doctor will study the results along with your medical record, screenings, physical condition, symptoms and any other relevant information about your situation.

There are some circumstances that can alter the normal ranges:

  • RBC are increased 0.15 to 0.25 million/ µl per km of altitude
  • In post-menopause women, there is an increase in RBC normal range to be similar to men ranges.
  • Above 65 years old there is a progressive reduction in the RBC count for both genders.
  • During pregnancy, RBC count is lower than normal and the normal count is specific for each trimester of pregnancy.

What is RBCs (Red Blood Cell) count?

RBC (Red Blood Cells), also called erythrocytes, are the cells that carry oxygen from the lungs to the body tissues.

Inside the red blood cells, there is a protein called hemoglobin that can contain iron to bind oxygen molecules and that gives RBC its red color.

Hemoglobin is, ultimately, the responsible to carry the oxygen around the body through the bloodstream and to collect the carbon dioxide away from the tissues and back to the lungs to be breathed out.

RBCs have a biconcave shape and with a mean lifespan of 115 days.

RBC cells are created in the red bone marrow. The erythropoietin hormone, secreted mainly by the kidney, stimulates the production of RBCs by the bone marrow. If there is a lack of oxygen in the cells of the body there will be an increase in erythropoietin hormone production, which finally it will increase the production of RBC by the bone marrow (erythropoiesis).

What is the RBC count used for?

RBC count is used to know the overall health status, the possible existence of an anemia, a general disease or a cancer.

The RBC count test should be studied for a better diagnosis along with other blood tests such as the hemoglobin, the hematocrit, MCV (Mean Corpuscular Volume), MCH (Mean Corpuscular Hemoglobin) and MCHC (Mean Corpuscular Hemoglobin Concentration).

A low RBC count, called erythrocytopenia, usually comes with a low hemoglobin level in the blood in what is called anemia. There are different types of anemia for example, iron deficiencyanemia (lack of iron), megaloblastic anemia (lack of Vitamin B12 or folic acid) or hemolytic anemia (premature destruction of erythrocytes). Aplastic anemia where the bone marrow does not produce enough new blood cells also cause erythrocytopenia.

Another possibility for a low RBC count is an excessive bleeding (menstruation, etc.) or kidney disorders that may reduce the production of erythropoietin hormone.

The RBC count may be elevated for many pathologic reasons. Erythrocytosis may be:

  • Relative: There is a decrease in blood plasma, maybe due to dehydration, and therefore the RBCs are more concentrated in the blood.
  • Absolute: It implies that it is a true (vera) increase in RBC count and it is usually due to a genetic disorder called polycythemia vera.

Respiratory diseases that cause tissue hypoxia increase the secretion of erythropoietin and therefore an increase in RBC.

Where can I find more information about RBC count in the blood?

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Which values are considered a normal RBC count in the blood?

The following values are considered to be normal values:

IMPORTANT: These levels are expressed in mill/µl (microliter). They are an example of a healthy woman of about 45 years old with no known disease and not taking any medication. The ranges can be different depending on the laboratory or on your personal circumstances.

RBC Count
4 mill./µl4.1 mill./µl4.2 mill./µl4.3 mill./µl4.4 mill./µl4.5 mill./µl4.6 mill./µl4.7 mill./µl
4.8 mill./µl4.9 mill./µl5 mill./µl5.1 mill./µl5.2 mill./µl5.3 mill./µl5.4 mill./µl5.5 mill./µl
Medically reviewed by our Medical staff on 02/12/2020


  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 214.
  • Laboratory tests and diagnostic procedures with nursing diagnoses (8th ed), Jane Vincent Corbett, Angela Denise Banks, ISBN: 978-0-13-237332-6, Pag. 25.

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