Haematocrit (HCT)

What is Haematocrit (HCT)?

Haematocrit measures how much space (volume) red blood cells occupy in the blood. Haematocrit is also known as packed cell volume (PCV) and increases when the number of red blood cells increases or decreases^[1].

What are Normal Haematocrit Levels?

The NHS states that the normal haematocrit reference ranges are:

Data collected from Forth customers shows the average haematocrit levels across different age ranges are:

Graph 1: Average haematocrit levels by age and sex. Our data demonstrates that Forth customers are within the optimal haematocrit range across all age groups and sexes.

What Can Cause High Haematocrit?

High haematocrit can be a sign of several conditions. The most common causes are dehydration and polycythaemia.

Dehydration

One of the most common causes of high haematocrit is dehydration. That’s because dehydration reduces the water content in the body, including in the blood. So, less water in the blood increases the ratio of cells to blood volume, raising haematocrit levels. When dehydration is treated, haematocrit should return to normal.

Polycythaemia

Polycythaemia is a condition that causes a high number of red blood cells. It makes the blood thicker and more difficult to travel through the blood vessels, causing several symptoms.

Polycythaemia vera is a type of blood disorder that causes an increase in red cells and is a primary cause. Polycythaemia can also be caused by other conditions, known as secondary causes^[3], like:

• Testosterone therapy
• Chronic lung disease
• Kidney disease
• Chronic obstructive pulmonary disease (COPD)^[4]

What are the most common symptoms?

Not everyone will experience symptoms if they have polycythaemia, but many people do. Polycythaemia symptoms include:

• Blurred vision
• Headaches
• Tiredness
• High blood pressure
• Red skin (face, hands, feet)
• Dizziness
• Concussion
• Nosebleeds and bruising
• Tummy discomfort
• Gout
• Itchy skin^[5]

What Can Cause Low Haematocrit?

Anaemia is a common cause of low haematocrit. Anaemia is characterised by reduced haemoglobin, haematocrit, or red blood cell count^[6]. It means your body doesn’t have enough red blood cells needed to transport oxygen around the body.

There are many different types of anaemia, depending on the underlying cause. Anaemia is caused by:

• Blood loss (internal or external bleeding)
• Nutrient deficiencies (iron, vitamins B6 and B12, folate)
• Kidney disease
• Some types of cancer
• Thyroid conditions

What are the most common symptoms?

Anaemia causes many symptoms, including:

• Fatigue
• Shortness of breath
• Light-headedness or dizziness
• Headaches
• Cold hands and feet^[7]

How to Manage Your Haematocrit Levels

If you have polycythaemia or anaemia, you’ll likely need to speak to your GP for advice and treatment. However, you can manage your haematocrit levels by making certain lifestyle choices.

Stay hydrated

Dehydration is a common cause of high haematocrit but can usually be avoided with an adequate fluid intake. It is recommended that adults should drink 6 to 8 glasses of fluid a day which can include water, low-fat milk, sugar-free squash, tea and coffee^[8]. You may need to increase your fluid intake if greater demand is placed on your body, such as during:

• Pregnancy
• Hot weather
• Prolonged exercise
• Illness and periods of recovery

Diet

Nutritional deficiency is a common cause of anaemia, so eating a healthy balanced diet is important to ensure you get all the vitamins and minerals your body needs.

Iron deficiency is the most common nutritional cause of anaemia, but low folate, vitamin B6 or B12 intake can also cause the condition^[9]. To help prevent anaemia you should ensure you are eating the following:

Because the most bioavailable sources of vitamin B12 are found in animal products, anyone who follows a vegan or vegetarian diet is at a greater risk of deficiency. Therefore, these individuals may need to consider supplementing their diet.

Written by Leanne Edermaniger

Based in the UK, Leanne specialises in writing about health, medicine, nutrition, and fitness.

She has over 5 years of experience in writing about health and lifestyle and has a BSc (hons) Biomedical Science and an MSc Science, Communication and Society.