All About Iron
- Vitamin Clinics
- Feb 4
- 3 min read
Iron is an essential mineral with a central role in human health. It is critical for oxygen transport, energy production, immune function, and cognitive performance. Despite its importance, iron imbalance—both deficiency and overload—is common and often under-recognised without blood testing.
In this article, we explain how iron functions in the body, why testing matters, and how clinicians interpret the key markers included in an iron blood panel: Haemoglobin (Hb), Ferritin, Serum Iron, Total Iron Binding Capacity (TIBC), and Transferrin Saturation (TSAT).
Why Is Iron So Important?
Iron is a core component of haemoglobin, the protein in red blood cells that carries oxygen from the lungs to tissues throughout the body. Without sufficient iron, oxygen delivery becomes impaired, leading to symptoms such as fatigue, shortness of breath, reduced exercise tolerance, brain fog, and palpitations.
Iron is also involved in:
Cellular energy production (mitochondrial function)
DNA synthesis and repair
Immune system regulation
Neurotransmitter production
Because the body cannot actively excrete excess iron, iron balance is tightly regulated. This is why assessing multiple markers together is essential.
Understanding Iron Blood Tests
A comprehensive iron panel does not measure just one value. Instead, it looks at several interconnected markers that together provide a clearer picture of iron status.
Haemoglobin (Hb)
What it measures:The concentration of haemoglobin in the blood.
Why it matters:Haemoglobin reflects the blood’s oxygen-carrying capacity. Low haemoglobin defines anaemia, but it is important to understand that haemoglobin often falls late in iron deficiency.
Key point:You can have iron deficiency without low haemoglobin. Relying on Hb alone may miss early or functional iron deficiency.
Ferritin
What it measures:Ferritin reflects iron stored in the body, primarily in the liver, spleen, and bone marrow.
Why it matters:Ferritin is usually the most sensitive early marker of iron deficiency. Low ferritin almost always indicates depleted iron stores.
Clinical nuance:Ferritin is also an acute-phase reactant, meaning it can rise during inflammation, infection, or chronic illness—even when iron stores are low.
Key point:Low ferritin = iron deficiencyNormal or high ferritin does not always exclude deficiency if inflammation is present
Serum Iron
What it measures:The amount of circulating iron bound to transferrin in the blood at the time of the test.
Why it matters:Serum iron reflects short-term iron availability but fluctuates significantly throughout the day and with recent food intake.
Key point:Serum iron alone is rarely interpreted in isolation due to variability.
Total Iron Binding Capacity (TIBC)
What it measures:The blood’s capacity to bind iron, indirectly reflecting levels of transferrin (the iron transport protein).
Why it matters:When iron stores are low, the body increases transferrin production to capture as much iron as possible, leading to a higher TIBC.
Key point:High TIBC often suggests iron deficiencyLow TIBC may be seen in inflammation or iron overload states
Transferrin Saturation (TSAT)
What it measures:The percentage of transferrin binding sites that are occupied by iron.It is calculated using serum iron and TIBC.
Why it matters:TSAT reflects how much iron is immediately available for processes such as red blood cell production.
Key point:Low TSAT indicates reduced iron availability, even if ferritin appears normalThis is especially important in functional iron deficiency
How These Markers Work Together
Clinicians rarely interpret iron markers in isolation. Instead, they look at patterns:
Early iron deficiency:Low ferritin, normal haemoglobin
Established iron deficiency anaemia:Low ferritin, low serum iron, high TIBC, low TSAT, low haemoglobin
Functional iron deficiency (often seen in chronic illness):Normal or high ferritin, low serum iron, low TSAT
Iron overload states:High ferritin, high serum iron, low TIBC, high TSAT
This multi-marker approach allows for more accurate diagnosis and tailored treatment decisions.
Who Should Consider Iron Testing?
Iron testing can be particularly valuable for:
Individuals experiencing unexplained fatigue or weakness
Athletes and physically active individuals
People following vegetarian or vegan diets
Women with heavy menstrual bleeding
Those with digestive conditions affecting absorption
Individuals with chronic inflammation or autoimmune conditions
Iron Testing with Vitamin Clinics
At Vitamin Clinics, we offer both in-clinic and at-home blood testing options that assess iron status using clinically validated laboratories. Results are reviewed with appropriate clinical context, helping to identify deficiencies early and guide next steps safely and effectively.
As with all blood test results, interpretation should consider symptoms, medical history, and other biomarkers. If you have concerns about your iron levels, our clinical team is happy to discuss whether testing is appropriate for you.
Disclaimer:This article is for educational purposes only and does not replace personalised medical advice. Always consult a qualified healthcare professional before starting supplementation or treatment based on blood test results.
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