Iron-Deficiency Anaemia

Iron-deficiency anaemia (IDA) is the most common type of anaemia worldwide. It occurs when the body does not have enough iron to produce sufficient haemoglobin, the protein in red blood cells that carries oxygen. In the UK, IDA is commonly encountered in both primary and secondary care and is often a sign of underlying chronic disease or blood loss. Identifying and managing the underlying cause is just as important as treating the anaemia itself.

Causes

The most common causes of iron-deficiency anaemia include:

• Chronic blood loss (e.g., heavy menstruation, gastrointestinal bleeding due to ulcers, polyps, or cancers)
• Inadequate dietary intake of iron
• Poor absorption of iron (e.g., coeliac disease, post-gastrectomy, inflammatory bowel disease)
• Increased iron demand (e.g., during pregnancy, rapid growth in children)

Pathophysiology

Iron is crucial for making haemoglobin. When iron stores become depleted, the bone marrow cannot produce red blood cells effectively. Initially, the body uses stored iron in the liver, spleen, and bone marrow. As iron levels drop further, red blood cell production slows, and existing cells become smaller (microcytic) and paler (hypochromic), leading to anaemia and reduced oxygen delivery to tissues.

Signs and Symptoms

Symptoms of IDA often develop slowly and may include:

• Fatigue and weakness
• Shortness of breath, especially on exertion
• Dizziness or light-headedness
• Palpitations
• Headache
• Cold hands and feet
• Pale skin or conjunctiva
• Brittle nails, hair loss, or spoon-shaped nails (koilonychia)
• Craving non-food substances (pica), such as ice or clay in some cases
• Glossitis or mouth ulcers

Risk Factors

People at higher risk of developing iron-deficiency anaemia include:

• Women with heavy menstrual periods
• Pregnant women
• Infants and toddlers, especially with poor dietary iron intake
• Vegetarians and vegans not supplementing iron
• Older adults, particularly those with gastrointestinal conditions
• People with chronic inflammatory diseases or gastrointestinal surgery
• Frequent blood donors

Investigations

Initial tests include:

• Full blood count (FBC): Typically shows low haemoglobin, low mean corpuscular volume (MCV), and low mean corpuscular haemoglobin (MCH).
• Serum ferritin: A key marker for iron stores. Low ferritin confirms iron deficiency, though it can be elevated in inflammation.
• Serum iron, transferrin saturation, total iron-binding capacity (TIBC): These help confirm iron deficiency and assess iron transport and utilisation.
• Peripheral blood film: Shows microcytic, hypochromic red cells.
• Further investigations aim to find the underlying cause:
  1. Faecal occult blood test (FOBT) or faecal immunochemical test (FIT) for GI bleeding
  2. Upper and lower GI endoscopy in adults with unexplained anaemia or red-flag symptoms
  3. Coeliac screening
  4. Pelvic ultrasound in premenopausal women with heavy menstrual bleeding

Management

1. Non-Pharmacological Management

• Dietary advice: Encourage iron-rich foods such as red meat, liver, leafy greens, legumes, and iron-fortified cereals.
• Vitamin C intake enhances iron absorption and should be consumed alongside iron-rich meals.
• Identify and treat the cause: E.g., refer for gynaecological or gastrointestinal evaluation as appropriate.

2. Pharmacological Management

• Oral iron therapy is first-line. Common formulations include ferrous sulphate, ferrous fumarate, or ferrous gluconate. Typically, 100–200 mg of elemental iron daily is prescribed.
• Side effects include nausea, constipation, abdominal discomfort, and dark stools.
• Advice: Take on an empty stomach with water or orange juice. Avoid tea, coffee, and dairy products around the time of dosing.
• Parenteral iron (IV iron) is reserved for those who cannot tolerate oral iron or when rapid replenishment is needed (e.g., severe anaemia or active bleeding).
• Treatment should continue for 3 months after haemoglobin normalises to replenish iron stores.

3. Surgical Management

There is no direct surgical treatment for IDA, but surgery may be necessary if a structural cause is found, such as GI tumour resection, endometrial ablation, or polypectomy.

Complications

If untreated, IDA can result in:

• Severe fatigue and reduced quality of life
• Impaired cognitive and physical function
• Pregnancy complications (e.g., preterm delivery, low birth weight)
• Increased cardiovascular strain leading to angina or heart failure in vulnerable individuals
• Poor wound healing and increased risk of infections
• Chronic undiagnosed blood loss may also point to serious underlying conditions, including malignancy.

References

• NICE Clinical Knowledge Summary: Anaemia – Iron Deficiency (2022)
• NICE NG8: Anaemia management in chronic kidney disease (2015)
• Royal College of Physicians: Investigation and Management of Anaemia in Adults
• British Society of Gastroenterology guidelines on iron deficiency anaemia (2021)
• General Medical Council (GMC): Good Medical Practice