Red blood count (RBC) is a blood test that tells you how many red blood cells you have.
Red blood cells contain a substance called hemoglobin, which carries oxygen throughout the body.
The amount of oxygen brought into your body's tissues depends on the number of red cells you have and how well they function.
RBC counts are usually performed as part of the total blood count (FBC).
Women tend to have lower RBCs than men, and red cell count tends to decrease with age.
A normal RBC count would be:
- men – 4.7 to 6.1 million cells per microlitre (cells/mcL)
- women – 4.2 to 5.4 million cells/mcL
The results of the RBC count can be used to diagnose blood-related conditions, such as iron deficiency anemia (when there are fewer red blood cells than normal).
Low RBC levels may also indicate a deficiency of vitamin B6, B12 or folate.
It can also indicate internal bleeding, kidney disease or malnutrition (when a person's diet does not have enough nutrients to meet his or her body's needs).
High RBC counts can be caused by a number of health conditions or health-related factors, including:
- smoking
- congenital heart disease
- dehydration (for example, from severe diarrhea)
- low oxygen levels in the blood (hypoxia)
- pulmonary fibrosis (a condition of the lungs that causes lung shock)
Learn more about red cell counts in Lab Tests Online