Complete Blood Count (CBC)

Red Blood Cells (Erythrocytes / RBC)

Optimal Result: 3.77 - 5.28 cells/mcL, 3.77 - 5.28 x10^12/L, or 3.77 - 5.28 x10/12/l.

Red blood cells (RBCs) are the most plentiful type of cell in the blood (~40% to 45% of the body's blood supply. They carry oxygen to the tissues and organs. They also bring back carbon dioxide back to the lungs so that it can be removed (exhaled) from the body. Red blood cells get their color from the protein hemoglobin. RBCs are constantly being replenished and they have a lifespan of around 120 days. Red blood cells are also known as erythrocytes, red cells, haematids, and erythroid cells. Red blood cells perform this important role for humans and are the main way that all animals with a backbone (vertebrates) get oxygen delivered to the tissues. A red blood cell count is usually performed during a routine physical and is used to help diagnose polycythemia (high red blood cell count), anemia (low blood cell count), and various other blood disorders. If an abnormality is detected, other values in the complete blood count, or CBC, are examined to identify the cause of the imbalance.

Reference Ranges for Red Blood Cells in x10E6/µL:

Men: 4.7 to 6.1

Women: 4.2 to 5.4

Children up to 18 years of age: 4.0 to 5.5

Infants: 4.8 to 7.1

What does it mean if your Red Blood Cells (Erythrocytes / RBC) result is too low?

Anemia (low blood cell count) is the most common blood disorder among the US population. Anemia can be grouped into three main categories: 

- Caused by bleeding

- Caused by the reduction of red blood cells or the production of defective red blood cells. 

- Caused by the premature destruction of red blood cells. 

What does it mean if your Red Blood Cells (Erythrocytes / RBC) result is too high?

There are numerous reasons for a high red blood cell count, or polycythemia. RBC production increases when the body's oxygen levels are low because of a medical condition or because the external oxygen supply is limited (for example at high-altitude locations). 

High RBC count can be triggered by various factors, including:

- Bone Marrow Disorder

- Smoking

- Dehydration

- Living at high altitude

- Chronic Obstructive Pulmonary disease [L]

- Congential heart disease

- Heart failure

- Genetic defects that impair the ability of RBC to transport oxygen efficiently (Hemoglobinopathies)

- Kidney Cancer

- Kidney Transplant

- Medications such as anabolic steroids, erythropoietin (EPO), genta micin (Gentamicin), and methyldopa (Aldomet)

- Pulmonary fibrosis

- Various types of heart and lung disease

- Testosterone replacement therapy (read blog article here)


Some people may not produce any symptons, while others may have nonspecific symptons such as adominal bloating, dizziness, fatigue and headache. Physical indicators such as chest pain and shortness of breath are also possible, particulary in those who have heart or respiratory problems due to their high red blood cell count. 

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