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Transferrin Saturation

Transferrin saturation quantifies how much iron is bound to transferrin for transport around the body, but what do fluctuations in this biomarker tell us about our health?

Author: Leanne Edermaniger

May 21, 2024

Reviewed by: Dr Thom Phillips

In this article:

What is Transferrin Saturation?

Transferrin saturation tells you how much iron is bound to transferrin (a protein that transports iron in the blood and helps regulate iron levels in the body) in the blood. The test determines a person’s iron status by giving the ratio of serum iron concentration and total iron binding capacity (TIBC) as a percentage.

Transferrin saturation is used to diagnose iron deficiency but it can also indicate anaemia and pregnancy when levels are low. High transferrin saturation may be associated with an increased risk of cancer[1].

Difference between transferrin and ferritin

Transferrin is a protein produced by the liver which is responsible for binding to iron and delivering it around the body.

Serum ferritin levels indicate how much iron is stored in the body. Ferritin isn’t the same thing as iron. Instead, ferritin is the protein that stores iron in the body. Transferrin, on the other hand, is another transport protein for iron and can indicate the body’s iron binding capacity[2].

Low serum ferritin levels or transferrin saturation are indicative of iron deficiency[3].

What is a Healthy Transferrin Saturation Range?

A normal value range for transferrin saturation is 20% to 50%.

If transferrin saturation is less than 20% it could indicate iron deficiency while above 50% could mean iron overload, also known as haemochromatosis.

What Does A High Transferrin Saturation Percentage Mean?

A high transferrin saturation could mean an individual has haemochromatosis or iron overload. Haemochromatosis is an inherited condition which causes iron levels to build up in the body over a long period. It means that the body absorbs too much iron from the diet which can cause damage to various organs.

Because iron builds up over many years, many people do not experience symptoms until they are in their 30s or 40s, although this can be later for women[4].

Early haemochromatosis symptoms include:

  • Fatigue
  • Weight loss
  • Joint pain
  • Weakness
  • Mood swings
  • Depression
  • Anxiety
  • Irregular periods or no periods at all
  • Erectile dysfunction in men

If the condition goes undiagnosed or continues to progress, it may also cause:

  • Low libido
  • Tummy pain and swelling
  • Extreme thirst
  • Needing to pee more often
  • Yellowing of the skin
  • Shortness of breath
  • An irregular heartbeat
  • Chest pain
  • Severe pain and stiffness in the joints, especially the fingers[5]

Some research shows that a high transferrin saturation and high serum iron levels were associated with an increased risk of non-skin cancer including breast cancer[1].

What Does A Low Transferrin Saturation Percentage Mean?

Low transferrin saturation is associated with iron-related conditions including iron deficiency, anaemia, and pregnancy.

Iron deficiency is caused by a reduction in the total amount of iron in the blood. This can progress to iron deficiency anaemia if it is severe enough to interrupt the production of red blood cells[6].

Iron deficiency is usually diagnosed if a person has high total iron binding capacity or transferrin, or has low transferrin saturation[7].

Iron deficiency anaemia is the most common type of anaemia and is caused by any of the following:

  • Blood loss
  • Low dietary intake
  • Impaired iron absorption
  • Gastrointestinal bleeding
  • Cancer[8]

Iron deficiency is common in people with cancer[9]. Although the link between the two is complex, iron deficiency can occur for several reasons, including medication such as chemotherapy, malnutrition, and bleeding[10]. Some recent evidence shows that low dietary iron intake is associated with the development of colorectal cancer, the fourth most commonly diagnosed cancer worldwide[11].

Common symptoms of low iron:

  • Tiredness and low energy
  • Pale skin
  • Shortness of breath
  • Heart palpitations
  • Headaches[12]

How to Check Your Transferrin Saturation

Transferrin saturation can be measured with a blood test, sometimes called a T-Sat.

However, transferrin saturation measurements can be unstable and serum iron levels can change over the day and when you eat iron-containing foods. So, at Forth we measure how much iron is stored in the body with the Ferritin Blood Test.

A serum ferritin test is the most reliable biomarker to determine the iron stores in the body. Low levels indicate low iron stores in most people, although they can be unreliable in the second or third trimester of pregnancy.

A serum ferritin level below 30 micrograms per litre (mg/L) diagnoses iron deficiency. A high serum ferritin level may suggest the presence of inflammation or infection, even if iron deficiency is suspected[13].

How to Improve Your Transferrin Saturation

Low transferrin saturation is most commonly linked to iron deficiency. It is important to keep your iron levels within balance because fluctuations either way can impact health.

Here are some of the ways iron levels can be increased which will subsequently improve transferrin saturation:

Eat iron-rich foods

There are two main types of dietary iron available: haem and non-haem iron.

Haem iron is found in animal-based foods like poultry, red meat and seafood, whereas plants and fortified foods contain non-haem iron[14]. Haem iron is the most easily absorbed of the two with red meat being the most prominent source[15].

Haem iron sources Non-haem iron sources
Beef Spinach
Lamb Lentils
Offal Tofu
Pork Beans
Chicken Peas
Turkey Kale
Oysters Broccoli
Sardines Nuts
Tuna Seeds[16]

Aim to eat red meat once a week to help keep iron levels within a healthy range. Menstruating women will need to increase their iron intake, particularly around the time of their periods to compensate for the blood loss.

Anyone who follows a vegan or vegetarian diet will need to increase their consumption of plant and iron-fortified food sources.

Enhance iron absorption

There are foods which can help improve iron absorption and those which can harm it. It’s important to know which foods to eat with iron-rich sources to promote its absorption.

When eating non-haem iron, like that found in plants such as spinach, kale, and broccoli, it’s important to pair it with vitamin C. Ascorbic acid (vitamin C) is known for its powerful absorption enhancing properties of non-haem iron[17].

However, drinking tea or coffee can reduce iron absorption, so drinks like these are best avoided at meal times[18]. Research has shown that coffee can reduce iron absorption from a hamburger meal by 39% and tea results in a 64% reduction[19].

Cast iron cookware increases iron absorption

Research has shown that cooking in cast iron pots improves the iron content of food and iron bioavailability. Although more research needs to be conducted, it appears that cast iron cookware could have a positive effect, especially for increasing the bioavailability of haem iron[20].

Iron supplements

For most people, all the iron that the body requires can be achieved by eating a healthy, balanced diet. However, if your iron levels are low, a doctor may prescribe iron replacement therapy or supplements.

Consuming too much iron or taking too many iron supplements can have negative health consequences, so you should follow the instructions of your doctor. If you take iron supplements by choice, then taking 17 mg or less per day is unlikely to cause harm[21].

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.

Article references

  1. Al-Naseem, A. et al. (2021) ‘Iron deficiency without anaemia: A diagnosis that matters’, Clinical Medicine, 21(2), pp. 107–113. doi:10.7861/clinmed.2020-0582.

  2. Aksan, A. et al. (2021) ‘Flipside of the coin: Iron deficiency and colorectal cancer’, Frontiers in Immunology, 12. doi:10.3389/fimmu.2021.635899.

  3. TBC

  4. ‘Inhibition of iron absorption by coffee and the reduced risk of type 2 diabetes mellitus’ (2007) Archives of Internal Medicine, 167(2), p. 204. doi:10.1001/archinte.167.2.204-b.

This article was written by Leanne Edermaniger

This information has been medically reviewed by Dr Thom Phillips

Thom works in NHS general practice and has a decade of experience working in both male and female elite sport. He has a background in exercise physiology and has published research into fatigue biomarkers.

Dr Thom Phillips

Dr Thom Phillips

Head of Clinical Services