Haemoglobin

What is Haemoglobin?

Haemoglobin is a complex protein found in red blood cells responsible for transporting oxygen from the lungs to the peripheral tissues and carbon dioxide from the tissues to the lungs where it can be removed from the body^[1].

Each red blood cell contains several hundred million haemoglobin molecules^[2]. Structurally, haemoglobin consists of four subunits, each containing a haem group with an iron atom in the middle.

The iron atom is what binds to oxygen and allows each molecule of haemoglobin to carry four oxygen molecules at the same time^[3]. High or low haemoglobin levels can indicate an imbalance between red blood cell production and destruction, such as anaemia or polycythaemia.

Haemoglobin regulates blood pH to keep it within the normal arterial range of 7.36 and 7.42^[4]. It also transports other blood gases such as nitric oxide.

What are normal haemoglobin levels by age?

Women often have a lower haemoglobin level than men. Haemoglobin levels may decrease with age. Some research shows that 17% of people over 65 are anaemic^[6]. However, our data shows that haemoglobin levels remain relatively steady and are within a healthy range for both sexes across all age groups.

What are dangerously high/low levels of haemoglobin?

These levels will vary according to the testing laboratory. A doctor should review your results and determine if haemoglobin levels are dangerous.

According to the National Cancer Institute, severely low haemoglobin levels are between 65 and 79 g/L and life-threatening levels are below 65 g/L^[7]. If haemoglobin levels are above 180 g/L if you are a man or 160 g/L for a woman, then it’s likely these results will require further investigation.

High Haemoglobin Levels

High haemoglobin levels are also known as polycythaemia.

Polycythaemia or erythrocytosis causes a high concentration of red blood cells. It makes the blood thicker and less able to flow fluidly through the blood vessels and organs^[8].

There are several types of polycythaemia depending on the underlying cause:

• Apparent polycythaemia: Normal red cell count but low plasma levels.
• Relative polycythaemia: Similar to apparent polycythaemia but often caused by dehydration.
• Absolute polycythaemia: The body produces too many red blood cells. There are two types; primary polycythaemia and secondary polycythaemia^[9].

What causes high levels?

High haemoglobin levels are caused by absolute polycythaemia, resulting in high numbers of red blood cells circulating in the blood.

Primary polycythaemia

Primary polycythaemia or polycythaemia vera is a rare condition caused by an issue in the cells produced by the bone marrow. A fault in a gene called JAK2 is the primary cause and results in the bone marrow cells producing abnormally high numbers of red blood cells.

Secondary polycythaemia

Secondary polycythaemia is an underlying condition that causes the kidneys to produce too much erythropoietin, a hormone that stimulates the bone marrow to produce red blood cells.

Some of the conditions that cause secondary polycythaemia include:

• Chronic obstructive pulmonary disease (COPD)
• Sleep apnoea
• Kidney issues including kidney cancer

Other causes of high haemoglobin levels include:

• Living at high altitudes: People who live at high altitudes often have higher haemoglobin levels because their bodies get used to the lower oxygen concentrations by increasing the number of red blood cells to compensate.
• Dehydration: Haemoglobin concentrations increase if you are dehydrated because of a low plasma volume.
• Anabolic steroid use: Athletes who use performance-enhancing drugs such as dehydration, can artificially increase haemoglobin levels.
• Smoking: Smoking increases haemoglobin levels as the body compensates for the reduced oxygen levels caused by carbon monoxide in cigarette smoke.
• Heart disease: Some heart conditions that cause lower blood oxygen levels can stimulate the body to produce more red blood cells, raising haemoglobin.

Can stress cause high haemoglobin?

Scientists have found evidence that haemoglobin gene expression is regulated by cellular stress. This is particularly evident in people who live at high altitudes^[10].
Limited research shows that haemoglobin levels are raised in people with depression or anxiety when adjusted for socio-demographics. However, after full adjustment, these results weren’t significant. Therefore, stress itself may not typically be a direct cause of high haemoglobin levels, but it may influence other factors that can raise haemoglobin levels, such as:

• Exacerbating current chronic conditions or causing an increase in habits like smoking
• Influencing unhealthy behaviours such as poor diet, lack of exercise, or poor sleep

Symptoms of high levels?

Not everyone with polycythaemia gets symptoms, but lots do.

The symptoms include:

• Headaches
• Blurred vision
• Tiredness
• High blood pressure
• Red skin
• Tummy discomfort
• Confusion
• Nosebleeds
• Bruising
• Gout
• Itchy skin

Managing high levels

Making healthy lifestyle changes is important if you have high haemoglobin levels because they may help improve your symptoms, but can also reduce the risk of potentially serious side effects. For example, if you have polycythaemia, you are at an increased risk of developing a blood clot.

Diet changes

Although making changes to your diet will not cure polycythaemia, they can lower the risk of complications, such as blood clots, kidney stones, and fatigue. The dietary changes you’ll need to make aren’t difficult to manage and will ultimately help you follow a healthy, balanced diet pattern.

Foods to include	Foods to avoid
Calcium-rich foods: bananas, broccoli, dairy	Excess purine: found in meat, seafood, alcohol
Lean protein: healthy cuts of red meat, poultry, eggs	Excess oxalate: beans, berries, chard, leafy green vegetables
Fruit: apples, cherries, oranges	Excess refined sugar: sweets, biscuits, cakes, high-sugar drinks
Vegetables: carrots, onions, peppers, sweet potatoes	High-fat foods: cakes, fatty cuts of meat, butter
Nuts: almonds, Brazil, cashews, walnuts	Deep-fried foods: chips, onion rings, doughnuts, fried chicken
Water: drink plenty of water throughout the day	Processed foods: deli meat, crisps

Quit smoking

Smokers have increased haemoglobin levels compared to non-smokers to compensate for the reduced oxygen-carrying capacity. So, quitting smoking or avoiding tobacco can effectively manage haemoglobin levels^[11]. Smoking is also associated with an increased risk of adverse health events such as blood clots which are also an adverse effect of polycythaemia^[12].

Avoid high altitudes

Living or visiting places of high altitude causes high haemoglobin levels because the body will compensate for the increased oxygen need. So, it is best to avoid these places if you have high haemoglobin.

Avoid alcohol

Similar to smoking, alcohol increases haemoglobin levels in regular drinkers^[13]. Drinking more than seven drinks per week increases haemoglobin by 1.3%, so keeping alcohol consumption to a minimum may be beneficial.

Low Haemoglobin Levels

Low haemoglobin levels can indicate several conditions and cause uncomfortable symptoms because of the body’s reduced oxygen-carrying capacity.

What causes low levels?

There are several causes of low haemoglobin levels:

• Your body isn’t making enough red blood cells

• Your body produces an adequate amount of red blood cells but they die off quicker than you can replace them

• You’re losing blood from injury or illness e.g., internal bleeding, ulcers, heavy menstrual periods

• Your body cannot absorb iron which affects your body’s red blood cell production

• You’re not eating enough iron, vitamin B12 or B9

Some of the conditions that affect red blood cell production are:

• Certain cancers like lymphoma and leukaemia

• Anaemia

• Chronic kidney disease

• Inflammatory diseases

• Liver cirrhosis

• Vitamin deficiencies

• Chemotherapy^[14]

What’s the main cause of low levels?

When the body doesn’t have enough haemoglobin or red blood cells, anaemia occurs. Iron deficiency is the most common nutritional cause of anaemia^[15].

Symptoms of low levels

Anaemia causes a reduction in haemoglobin levels.

Symptoms include:

• Tiredness

• Weakness

• Shortness of breath

• Pale skin

• Irregular heartbeat

• Chest pain

• Reduced exercise tolerance

• Restless legs

• Cold hands and feet^[16]

Managing low levels

How do you fix low levels?

It’s important to identify the underlying cause of low haemoglobin. For example, further tests may be required to determine if iron deficiency is the cause. Your doctor may prescribe iron supplements or recommend an iron-rich diet. In most cases, treating the underlying cause of anaemia will raise your haemoglobin levels.

How to treat low levels

There are many causes of low haemoglobin levels and it is important to find out the underlying cause. You can do this by testing your haemoglobin levels or your doctor will be able to conduct tests to rule out possible causes. However, there are things you can do to help support and maintain haemoglobin production.

One way to support red blood cell production is to eat a balanced diet incorporating the nutrients needed for healthy red blood cell production.

Iron	Liver Red meat Red kidney beans Edamame beans Chickpeas Nuts Fortified breakfast cereals[17]
Vitamin B9	Beef liver Spinach Fortified cereals White rice Asparagus Brussels sprouts Broccoli[18]
Vitamin B12	Beef liver Oysters Clams Salmon Tuna Milk Yoghurt Cheese Eggs Turkey[19]

You should also consider if you need to supplement your diet. For example, anyone who follows a vegan diet is at risk of iron or B12 deficiency as the most reliable sources of these nutrients are animal-based products.

Exercise can raise haemoglobin levels, enhancing the oxygen-carrying capability of red blood cells^[20]. If you are anaemic, gentle exercises can help, but you should consult your doctor before trying anything new. Gentle exercises that can help include:

• Walking

• Cycling

• Swimming

• Dancing

Testing Your Haemoglobin

Haemoglobin is usually tested as part of a full blood count, but you can test your levels at home with the following blood test kits:

• Baseline Health Check
• Advanced Health Check
• Ultimate Health Check

All these tests also check your ferritin levels which tell you how much iron is stored in the body. If your ferritin levels are low, it could suggest your iron stores are also low, and you could be at risk of anaemia.

The test can be completed at home. Your test kit will arrive with everything you need to collect your sample at home or you can have it taken at a Superdrug health clinic or by a visiting nurse.

To get the most accurate picture of your health we recommend you are well hydrated at the time of your test and collect your sample within three hours of waking.

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.