A normal red blood cell count for males is 4.7 to 6.1 million cells per microliter, and a normal count for females is 4.2 to 5.4 million cells per microliter, states MedlinePlus. Normal ranges may vary from lab to lab, and some labs may use a different form of measurement.
A red blood cell count is done to help physicians diagnose issues such as anemia, dehydration and low blood oxygen level, notes MedlinePlus. A low red blood cell count can be caused by pregnancy or health conditions ranging from malnutrition to leukemia. High red blood cell counts may be the result of scarring of the lungs, bone marrow disease or cigarette smoking.