Understanding Iron Studies
Iron is a critical mineral for human health, playing a pivotal role in oxygen transport, energy production, and immune function. Iron studies, a panel of blood tests, provide essential insights into iron metabolism, helping clinicians assess health status and guide treatment. At FROM WITHIN we explore the components of an iron panel, their implications for health, how iron is transported in the body, why it is essential, the consequences of iron deficiency, and why supplementation should only be managed by healthcare professionals due to the risk of iron toxicity.
The Role of Iron in the Body
Iron is fundamental to numerous physiological processes, with about 70% of the body’s iron residing in haemoglobin, the protein in red blood cells responsible for oxygen transport from the lungs to tissues (Pasricha et al., 2021). Iron is also a component of myoglobin, which stores oxygen in muscles, and enzymes involved in energy metabolism and DNA synthesis (Camaschella, 2015). Insufficient iron disrupts these functions, leading to significant health challenges.
Iron is transported in the bloodstream by transferrin, a protein produced by the liver that binds iron to prevent oxidative damage from free iron, which can generate harmful reactive oxygen species (Ganz, 2019). Ferritin stores iron in cells, primarily in the liver, spleen, and bone marrow, releasing it as needed (Anderson & Frazer, 2017). Hepcidin, a liver-produced hormone, regulates iron absorption in the intestines and its release from storage, maintaining iron homeostasis (Nemeth & Ganz, 2014).
Iron Studies: What Each Marker Means
In Australia, iron studies include serum iron, ferritin, transferrin, total iron-binding capacity (TIBC), and transferrin saturation. These tests collectively assess iron status and guide clinical decisions.
Serum Iron
Serum iron measures the iron bound to transferrin in the blood, reported in micromoles per litre (µmol/L). The reference range in Australian laboratories is typically 10–30 µmol/L for adults (Pathology Tests Explained, 2023). Low serum iron suggests iron deficiency, while high levels may indicate iron overload, such as in haemochromatosis (Ganz, 2019).
Ferritin
Ferritin reflects iron stores and is measured in micrograms per litre (µg/L). Normal ranges in Australia are approximately 30–300 µg/L for men and 15–200 µg/L for women (Camaschella, 2015). Low ferritin (<30 µg/L) is the most reliable marker of iron deficiency, while elevated levels may indicate inflammation, liver disease, or iron overload (Anderson & Frazer, 2017). Ferritin is an acute-phase reactant, so inflammation can elevate levels, complicating interpretation (Nemeth & Ganz, 2014).
Transferrin
Transferrin, the primary iron-transport protein, is measured in grams per litre (g/L), with a typical range of 2.0–3.6 g/L in Australian adults (Pathology Tests Explained, 2023). Transferrin levels increase in iron deficiency as the body attempts to capture more iron and decrease in iron overload (Lopez et al., 2016).
Total Iron-Binding Capacity (TIBC)
TIBC measures the blood’s capacity to bind iron, primarily via transferrin, and is reported in µmol/L, with a reference range of 45–80 µmol/L in Australia (Pathology Tests Explained, 2023). TIBC is high in iron deficiency and low in iron overload or inflammatory conditions (Pasricha et al., 2021).
Transferrin Saturation
Transferrin saturation, expressed as a percentage, is calculated as (serum iron ÷ TIBC) × 100, with a normal range of 20–50% in Australian adults (Pathology Tests Explained, 2023). A low transferrin saturation (<20%) indicates iron deficiency, while a high saturation (>50% in men, >45% in women) suggests iron overload, such as in hemochromatosis (Ganz, 2019).
Health Implications of Iron Deficiency
Iron deficiency is a global health issue, affecting over 2 billion people, and is the most common nutritional deficiency in Australia (Pasricha et al., 2021). It progresses from depleted iron stores (low ferritin) to iron-deficient erythropoiesis (low transferrin saturation) and, ultimately, iron deficiency anaemia (low haemoglobin) (Camaschella, 2015). The health impacts are significant and multifaceted.
Fatigue and Reduced Physical Performance
Iron deficiency impairs oxygen delivery, leading to fatigue, weakness, and reduced exercise capacity. Even before anaemia develops, individuals may experience decreased stamina and cognitive function due to insufficient iron for energy metabolism (Lopez et al., 2016).
Cognitive and Developmental Effects
In children, iron deficiency can impair cognitive development, resulting in reduced attention, memory, and academic performance (Pasricha et al., 2021). In pregnant women, it increases risks of preterm delivery and low birth weight, impacting neonatal health (Camaschella, 2015).
Immune Dysfunction
Iron is essential for immune function, and deficiency weakens T-cell and neutrophil activity, increasing infection susceptibility (Anderson & Frazer, 2017). This is particularly concerning in vulnerable populations, such as the elderly or those with chronic illnesses.
Cardiovascular Strain
In iron deficiency anaemia, the heart compensates for reduced oxygen-carrying capacity, potentially causing palpitations, shortness of breath, and, in severe cases, heart failure (Ganz, 2019).
Mitigating Iron Deficiency
Addressing iron deficiency involves dietary improvements, supplementation under supervision, and treating underlying causes.
Dietary Sources of Iron
Iron exists as haem iron (from animal sources e.g., red meat, poultry, and fish) and non-haem iron (from plant-based sources e.g., legumes, spinach, and fortified cereals). Haem iron is absorbed at 15–35%, compared to 2–20% for non-haem iron (Hurrell & Egli, 2010). Consuming vitamin C-rich foods enhances non-haem iron absorption, while phytates (in grains) and polyphenols (in tea and coffee) inhibit it (Lopez et al., 2016).
Identifying Underlying Causes
Iron deficiency may stem from inadequate intake, increased demand (e.g., pregnancy, growth), or blood loss (e.g., menstruation, gastrointestinal bleeding). Conditions such as coeliac disease or chronic bleeding must be addressed to manage deficiency effectively (Camaschella, 2015).
The Dangers of Iron Overload and Why Supplementation Requires Supervision
Excess iron is toxic, leading to oxidative stress and organ damage, particularly in the liver, heart, and pancreas (Ganz, 2019). Iron overload, often seen in hemochromatosis or from excessive supplementation, can cause fatigue, joint pain, skin pigmentation, and long-term risks such as cirrhosis, diabetes, and heart failure (Anderson & Frazer, 2017). In Australia, hemochromatosis is screened with transferrin saturation (>45–50%) and ferritin levels (>200 µg/L in premenopausal women, >300 µg/L in men and postmenopausal women) (Pathology Tests Explained, 2023).
Iron supplementation should only be managed by healthcare professionals. Self-prescribing can lead to toxicity, especially in individuals with normal or high iron stores. Acute high doses cause gastrointestinal distress, while chronic overuse may result in organ damage (Nemeth & Ganz, 2014). Clinicians use iron studies to determine supplementation needs, monitor progress, and adjust dosages. Intravenous iron or high-dose oral supplements are reserved for severe deficiency and administered under controlled conditions (Pasricha et al., 2021).
Practical Recommendations
To maintain healthy iron levels, consider these evidence-based strategies:
Incorporate Iron-Rich Foods: Include haem and non-haem iron sources in your diet. Pair plant-based sources with vitamin C to boost absorption and avoid tea or coffee when eating.
Monitor Symptoms: Watch for signs of iron deficiency, such as fatigue, pale skin, or shortness of breath, and consult a GP if symptoms persist.
Avoid Self-Supplementation: Never take iron supplements without medical guidance or seeing a clinical nutritionist, as they can mask underlying conditions or cause toxicity.
Regular Check-Ups: If you’re at risk for iron deficiency (e.g., pregnant, vegetarian, or experiencing heavy menstrual bleeding), request iron studies through your healthcare provider to monitor iron levels.
Iron studies are essential for assessing iron status and guiding treatment. Iron’s role in oxygen transport, energy production, and immune function highlights its importance, but its balance is critical. Iron deficiency can cause fatigue, cognitive impairment, and immune dysfunction, while excess iron is toxic, underscoring the need for professional oversight in supplementation. By understanding iron studies and adopting evidence-based dietary practices, you can support optimal health while avoiding the risks of deficiency or overload. If you’re concerned about your iron levels, and would like a personalised nutrition plan, book an appointment here.
References
Anderson, G. J., & Frazer, D. M. (2017). Current understanding of iron homeostasis. The American Journal of Clinical Nutrition, 106(Suppl_6), 1559S–1566S. https://doi.org/10.3945/ajcn.117.155804
Camaschella, C. (2015). Iron-deficiency anemia. New England Journal of Medicine, 372(19), 1832–1843. https://doi.org/10.1056/NEJMra1401038
Ganz, T. (2019). Systemic iron homeostasis and erythropoiesis. Hematology/Oncology Clinics, 33(5), 771–785. https://doi.org/10.1016/j.hoc.2019.05.005
Hurrell, R., & Egli, I. (2010). Iron bioavailability and dietary reference values. The American Journal of Clinical Nutrition, 91(5), 1461S–1467S. https://doi.org/10.3945/ajcn.2010.28674F
Lopez, A., Cacoub, P., Macdougall, I. C., & Peyrin-Biroulet, L. (2016). Iron deficiency anaemia. The Lancet, 387(10021), 907–916. https://doi.org/10.1016/S0140-6736(15)60865-0
Nemeth, E., & Ganz, T. (2014). Regulation of iron metabolism by hepcidin. Annual Review of Nutrition, 34, 123–140. https://doi.org/10.1146/annurev-nutr-071113-051227
Pasricha, S. R., Tye-Din, J., Muckenthaler, M. U., & Swinkels, D. W. (2021). Iron deficiency. The Lancet, 397(10270), 233–248. https://doi.org/10.1016/S0140-6736(20)30647-4
Pathology Tests Explained. (2023). Transferrin and total iron binding capacity (TIBC). https://www.pathologytestsexplained.org.au