Iron deficiency anaemia
- Iron deficiency is commonest cause of anaemia worldwide
- Results in hypochromic and microcytic red blood cells
- Diagnosis of iron deficiency is usually straightforward
- Determining the cause can be difficult
Iron metabolism
- The body contains about 5g of iron
- 70% is found in haemoglobin
- Daily dietary requirements are about 1 mg in a man and 3 mg in a women
- An average western diet contains about 15 mg of iron daily only 5-10% of which is absorbed
- Absorption occurs in the ferrous form in the upper part of small intestine
- Iron is carried to bone marrow by plasma transferrin
- Iron is stored bound to ferritin and as haemosiderin
- About 1 mg of iron is lost per day in urine, faeces and shed cells
- Menstrual losses account for an extra 20 mg per month
Clinical features
- Depend of rate of onset
- If insidious then symptoms are often few
- Commonest symptoms are of lethargy and dyspnoea
- Skin atrophy occurs in about 30% of patients
- Nail changes include koilonychia (spoon shaped nails)
- Patients may also develop angular stomatitis and glossitis
- Oesophageal and pharyngeal webs may be seen
- Examination should be directed to possible underlying cause
Causes of iron deficiency
- Increased blood loss - uterine, GI tract, urine
- Increased demands - prematurity, growth, child-bearing
- Malabsorption - post-gastrectomy, coeliac disease
- Poor diet
Investigations
- The following investigations may be required:
- Full blood count and blood film examination
- Haematinic assays (serum ferritin, vitamin B12and folate)
- Faecal occult bloods
- Mid-stream urine
- Endoscopic or barium studies of the GI tract
- Diagnosis of iron deficiency will be based on:
- Reduced haemoglobin (man <13.5 g/dl, woman <11.5
g/dl)
- Reduced mean cell volume (<76 fl)
- Reduced mean cell haemoglobin (<27 pg)
- Reduced mean cell haemoglobin concentration (<300 g/l)
- Blood film - microcytic, hypochromic red cells
- Reduced serum ferritin (<10 mg/l)
- Reduced serum iron ( man < 14mmol/l,
woman <11mmol/l)
- Increased serum iron binding capacity (>75 mmol/l)
- Diagnostic bone marrow examination is rarely required
- Other causes of a hypochromic microcytic anaemia include:
- Anaemia of chronic disease
- Thalassaemia trait
- Sideroblastic anaemia
Management
- Management of iron deficiency anaemia relies on:
- Identification and management of the underlying cause
- Iron replacement therapy
Iron replacement therapy
- Oral replacement with ferrous salts are the preferred option.
- Preparations include ferrous sulphate, fumarate and gluconate
- Provide approximately 200 mg of iron per day
- Side effects include epigastric pain, constipation and diarrhoea
- Effective treatment should increase haemoglobin concentration by 1 g/l/day
- Should continue for three months after normal haemoglobin achieved
- Intravenous iron preparations are available on named patient basis
- Severe side effects (e.g. anaphylaxis) may occur
- Injections can result in skin staining and arthralgia
- Should only be used when patients can not tolerate oral preparation
Bibliography
Jolobe O M. Does this elderly patient have iron deficiency anaemia and what is the underlying cause? Postgrad
Med J 2000; 76:195-198.
May R J, Early A R. Iron deficiency in childhood. J R Soc Med 1999; 92: 234-236.
Rockery D C. Occult gastrointestinal bleeding. N Eng J Med 1999; 341: 38-46.
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