A red blood cell (RBC) count is a blood test that tells you how many red blood cells you have.

Red blood cells contain a substance called haemoglobin, which transports oxygen around the body.

The amount of oxygen that's delivered to your body's tissues depends on the number of red blood cells you have and how well they work.

A RBC count is usually carried out as part of a full blood cell (FBC) count.

Women usually have a lower RBC count than men, and the level of red blood cells 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 an RBC count can be used to help diagnose blood-related conditions, such as iron deficiency anaemia (where there are less red blood cells than normal).

A low RBC count could also indicate a vitamin B6, B12 or folate deficiency.

It may also signify internal bleeding, kidney disease or malnutrition (where a person's diet doesn't contain enough nutrients to meet their body's needs).

A high RBC count could be caused by a number of health conditions or health-related factors, including:

• smoking
• congenital heart disease
• dehydration (for example, from severe diarrhoea)
• low blood oxygen levels (hypoxia)
• pulmonary fibrosis (a lung condition that causes scarring of the lungs)

Read more about the red blood cell count at Lab Tests Online UK.