Anaemia: iron deficiency
Iron-deficiency anaemia is the most common type of anaemia, which develops when there is a lack of iron in the body. Anaemia is defined as a haemoglobin level that is two standard deviations below the normal level depending on age and sex.
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Definition
Anaemia is defined as a haemoglobin level that is two standard deviations below the normal level depending on age and sex, as outlined below:
- men aged over 15 years – haemoglobin <130 g/L
- non-pregnant women aged over 15 years – haemoglobin <120 g/L
- pregnant women – haemoglobin <110 g/L throughout pregnancy
- children aged 12–14 years – haemoglobin <120 g/L (National Institute for Health and Care Excellence, 2023)
Iron-deficiency anaemia is the most common type of anaemia, which develops when there is a lack of iron in the body (National Institute for Health and Care Excellence, 2023). Iron metabolism is tightly regulated at multiple stages during the lifespan of red blood cells (erythrocytes).
The development of red blood cells from a multipotent myeloid stem cell is regulated by a hormone called erythropoietin (Peng et al, 2020). The differentiation from erythroblasts (polychromatic nucleated cells of red bone marrow) into reticulocytes (immature red
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Symptoms
Symptoms associated with iron deficiency anaemia (Table 1) depend on how quickly the condition develops. People with a chronic, slow decline may be able to tolerate very low levels of haemoglobin. Fatigue and mild dyspnoea after exertion may be the only symptoms in people with slow onset without other conditions (British Society for Gastroenterology, 2021). Chronic anaemia can lead to multiple health complications, for example individuals with heart failure and anaemia have greater cardiovascular risk and higher mortality rates (Savarese et al, 2023).
| Table 1. Common symptoms of iron deficiency anaemia | ||
| Very common symptoms | Common symptoms | Rare symptoms |
|
Dyspnoea Fatigue Dizziness, fainting and/or feeling lightheaded Palpitations Muscular weakness Increased sensitivity to cold Pale skin (pallor) or yellowish skin tone |
Cognitive dysfunction Restless leg syndrome Breathlessness Irregular heart rhythm Brittle nails Headaches, especially with physical activity |
Dysphagia Haemodynamic instability Syncope (loss of consciousness) Desire to eat ice or other non-food |
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Aetiology
Malabsorption
Certain conditions or medicines can decrease the body’s ability to absorb iron, leading to iron deficiency anaemia. Malabsorption is a disorder of the gastrointestinal tract that leads to defective digestion, deficiency and transport of important nutrients. The small intestine is where most of nutrients are absorbed. Intestinal conditions can cause reduced iron absorption from the gut, including:
- coeliac disease
- ulcerative colitis
- Crohn’s disease
- Helicobacter pylori infection (British Society for Gastroenterology, 2021)
Coeliac disease is usually confirmed by conducting a tissue transglutaminase immunoglobin A test (British Society for Gastroenterology, 2021). In coeliac disease, the immune system mistakenly sees gluten (a protein present in wheat, barley, rye and oats) as a foreign intruder. The body’s autoimmune response causes damage to the surface of the small bowel, affecting the intestine’s ability to absorb iron. Surgery on the stomach or intestines, including weight loss surgery, can also cause iron malabsorption (British
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Diagnosis
Diagnosis of iron deficiency anaemia is made by taking a history, performing examinations and specific investigations. Anaemia is usually identified on a full blood count sample result. The mean corpuscular volume often forms part of the sample result, as smaller red blood cells can be indicative of iron deficiency or thalassemia. Thalassaemia is an inherited condition that mainly affects people from Mediterranean, Asian and middle eastern origins (Imperial College Healthcare, 2023). The disease is caused by a faulty gene, and people with the condition produce very little or no haemoglobin.
Larger cells are a sign of pernicious anaemia (lack of vitamin B12) or autoimmune diseases, such as coeliac or Crohn’s disease. Serum ferritin level blood tests most reliably correlate with relative total body iron stores (Kell and Pretorius, 2014). However, ferritin levels increase in acute and chronic inflammatory conditions, malignant disease and liver disease (Kell and Pretorius, 2014). If
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Treatment
Iron deficiency can be treated with oral and/or intravenous (parenteral) iron. However, despite the potential benefits of oral iron, such as easy administration, its use is limited by poor gastrointestinal absorption and high rates of adverse events (Van Wyck et al, 2005). Lower and more infrequent administration of oral iron may be just as effective as twice- or three-times daily oral iron salts administration (Okam et al, 2017).
Initial treatment with oral iron can be prescribed as low as one tablet daily of either ferrous sulphate, fumerate or gluconate. If not tolerated, this dose can be reduced to one tablet on alternate days. The absorption of oral iron is impaired if taken with certain foods and tea. However, the inhibitory effect of tea on iron absorption dissipates within 1 hour (Ahmad et al, 2017).
People who have serious iron-deficiency anaemia or long-term conditions are more likely to receive parenteral iron.
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NMC proficiencies
Nursing and Midwifery Council: standards of proficiency for registered nurses
Part 1: Procedures for assessing people’s needs for person-centred care
1. Use evidence-based, best practice approaches to take a history, observe, recognise and accurately assess people of all ages:
1.2 physical health and wellbeing
Part 2: Procedures for the planning, provision and management of person-centred nursing care
11. Procedural competencies required for best practice, evidence-based medicines administration and optimisation
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Resources
Abbaspour N, Hurrell R, Kelishadi R. Review on iron and its importance for human health. J Res Med Sci. 2014;19(2):164-174
Ahmad Fuzi SF, Koller D, Bruggraber S, Pereira DI, Dainty JR, Mushtaq S. A 1-h time interval between a meal containing iron and consumption of tea attenuates the inhibitory effects on iron absorption: a controlled trial in a cohort of healthy UK women using a stable iron isotope. Am J Clin Nutr. 2017;106(6):1413-1421. https://doi.org/10.3945/ajcn.117.161364
Bager P, Dahlerup JF. Randomised clinical trial: oral vs. intravenous iron after upper gastrointestinal haemorrhage - a placebo-controlled study. Aliment Pharmacol Ther. 2014;39(2):176-187. https://doi.org/10.1111/apt.12556
British Dietetic Association. Iron. 2024. https://www.bda.uk.com/resource/iron-rich-foods-iron-deficiency.html (accessed 15 May 2024)
British Society for Gastroenterology. BSG guidelines for the management of iron deficiency anaemia in adults. 2021. https://www.bsg.org.uk/clinical-resource/guidelines-iron-deficiency-anaemia-in-adults (accessed 15 May 2024)
Fine NM. Heart failure (HF). 2022. https://www.msdmanuals.com/en-gb/professional/cardiovascular-disorders/heart-failure/heart-failure-hf (accessed 15 May 2024)
Imperial College Healthcare. About thalassaemia. 2023. https://www.imperial.nhs.uk/-/media/website/patient-information-leaflets/haematology/red-blood-cell-disease/about-thalassaemia.pdf?rev=b44c04000129464faa1ff7d049e56567 (accessed 15 May
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