Definition

By Mayo Clinic Staff

A high red blood cell count is an increase in a type of cells made in bone marrow and found in blood. The main job of red blood cells is to move oxygen from the lungs to the rest of the body. A condition that limits oxygen can cause a rise in red blood cell count. Other conditions can cause the body to make more red blood cells than it needs.

What's considered a high red blood cell count is different at different labs. For adults, the usual range is generally 4.35 to 5.65 million red blood cells per microliter (mcL) of blood for men and 3.92 to 5.13 million red blood cells per mcL of blood for women. In children, what's thought of as high depends on age and sex.

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Feb. 10, 2023