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

RBCs contain a substance called haemoglobin, which transports oxygen around the body. The amount of oxygen that’s delivered to your body’s tissues will depend on the number of RBCs you have and how well they work.

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

• male – 4.7-6.1 million cells per microlitre (cells/mcL)
• female – 4.2-5.4 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 due to a number of health conditions or 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.