Counts the number of red blood cells in a single drop of blood. "Normal" ranges vary according to age and sex. Men–4.5 to 6.2 million; Women 4.2 to 5.4 million; Children 4.6 to 4.8 million. A low RBC count may indicate anemia, excess body fluid, or hemorrhaging. A high RBC count may indicate polycythemia (an excessive number of red blood cells in the blood) or dehydration.