Red Blood Cell Count

The number of red blood cells, which carry oxygen around the body.

What it is

Your red blood cell count, often abbreviated as RBC or sometimes just 'red cells', is a measurement of how many red blood cells you have in a specific volume of your blood. Red blood cells are the most common type of blood cell and are produced in your bone marrow. Their primary job is to transport oxygen from your lungs to all the tissues and organs in your body, and to carry carbon dioxide, a waste product, back to your lungs to be exhaled. This count is a key part of a Full Blood Count (FBC), a common blood test.

Why it matters

The red blood cell count is important because it gives an indication of your body's ability to carry oxygen. If the count is too low, your body might not be getting enough oxygen, which can lead to symptoms like tiredness and breathlessness. If the count is too high, it could mean your blood is thicker than normal, which might make it harder for your heart to pump blood effectively and could increase the risk of blood clots. The typical reference range for red blood cells in adults is generally between 4.5 and 6.5 x 10^12 cells per litre (or 4.5–6.5 million cells per microlitre), though this can vary slightly between laboratories.

What can cause it to be high or low

A red blood cell count that falls outside the typical reference range can be associated with a number of different factors.

A higher than normal red blood cell count (polycythaemia) can sometimes be seen in people who live at high altitudes, as the body produces more red blood cells to compensate for lower oxygen levels in the air. It can also be associated with certain medical conditions, such as dehydration, where the blood becomes more concentrated, or more rarely, with conditions affecting the bone marrow's production of red blood cells, or certain kidney conditions. Smoking can also lead to a higher red blood cell count.

A lower than normal red blood cell count (anaemia) is more common and can be linked to various causes. Nutritional deficiencies, particularly a lack of iron, vitamin B12, or folate, are frequent culprits, as these are essential for red blood cell production. Chronic diseases, such as kidney disease or inflammatory conditions, can also affect red blood cell production. Blood loss, whether from heavy periods, internal bleeding, or injury, will naturally lower the red blood cell count. Some medications can also impact red blood cell levels, as can certain inherited conditions affecting red blood cells, like sickle cell anaemia or thalassaemia.

Lifestyle factors that may help

For individuals with a red blood cell count that is slightly outside the normal range, certain lifestyle adjustments might be discussed with a healthcare professional as part of a broader management plan.

Ensuring a balanced diet that includes sufficient iron, vitamin B12, and folate is often a key consideration, especially if a deficiency is identified as a contributing factor. Foods rich in iron include red meat, leafy green vegetables, and fortified cereals. Vitamin B12 is commonly found in animal products like meat, fish, and dairy, while folate is present in leafy greens, beans, and fortified grains.

Staying well-hydrated is also important, as dehydration can artificially increase the red blood cell count by concentrating the blood. Regular, moderate exercise can support overall cardiovascular health and circulation, though the impact on red blood cell count itself is complex and best discussed with a doctor. For those who smoke, quitting smoking is often advised, as it can have a significant impact on blood health, including red blood cell levels. Limiting alcohol intake may also be beneficial.

Questions to discuss with your GP

If your red blood cell count is outside the normal range, or if you have concerns about your blood health, it's always a good idea to have a conversation with your GP. Here are some questions you might consider discussing:

• What does my specific red blood cell count mean in the context of my overall health?
• Could my current medications or any recent illnesses be affecting my red blood cell count?
• Are there any specific dietary changes or supplements you would recommend I discuss further, based on my results?
• What are the potential long-term implications of having a red blood cell count that is consistently high or low?
• Are there any further tests that might be helpful to understand the reason for this result?
• What lifestyle changes, such as diet or exercise, might be most beneficial for me to consider?