Iron deficiency
The main causes of iron deficiency are:
• inadequate intake
• malabsorption
• blood loss.
Inadequate intake of iron is common in infants because additional iron is required for the increase in blood volume accompanying growth and to build up the child's iron stores (Fig. 22.5). A 1-year-old infant requires an intake of iron of about 8 mg/day, which is about the same as his father (9 mg/day) but only half that of his mother (15 mg/day).
Iron may come from:
• breast milk (low iron content but 50% of the iron is absorbed)
• infant formula (supplemented with adequate amounts of iron)
• cow's milk (higher iron content than breast milk but only 10% is absorbed)
• solids introduced at weaning, e.g. cereals (cereals are supplemented with iron but only 1% is absorbed).
Diagnostic approach to anaemia.
Iron deficiency may develop because of a delay in the introduction of mixed feeding beyond 4-6 months of age or to a diet with insufficient iron-rich foods, especially if it contains a large amount of cow's milk (Box 22.1). Iron absorption is markedly increased when eaten with food rich in vitamin C (fresh fruit and vegetables) and is inhibited by tannin in tea.
Infants should not be fed unmodified cow's milk as its iron content is low and poorly absorbed.
Clinical features
Most infants and children are asymptomatic until the Hb drops below 6-7g/dl. As the anaemia worsens, children tire easily and young infants feed more slowly than usual. They may appear pale but pallor is an unreliable sign unless confirmed by pallor of the conjunctivae, tongue or palmar creases. Some children have 'pica', a term which describes the inappropriate eating of non-food materials such as soil, chalk, gravel or foam rubber (see Case history 22.1). There is evidence that iron deficiency anaemia may be detrimental to behaviour and intellectual function. The history should include asking about blood loss and symptoms or signs suggesting malabsorption.
Dietary sources of iron
High in iron
Red meat - beef, lamb
Liver, kidney
Oily fish - pilchards, sardines, etc.
Average iron
Pulses, beans and peas
Fortified breakfast cereals with added vitamin C
Wholemeal products
Dark green vegetables - broccoli, spinach, etc.
Dried fruit - raisins, sultanas
Nuts and seeds - cashews, peanut butter, etc.
Foods to avoid in excess in toddlers
Cow's milk
Tea - tannin inhibits iron uptake
High-fibre foods - phytates inhibit iron absorption
Iron requirements during childhood.
Diagnosis
The diagnostic clues are:
• microcytic, hypochromic anaemia (low MCV and MCH)
• low serum ferritin.
The other main causes of microcytic anaemia are:
• β-thalassaemia trait (usually children of Asian, Arabic or Mediterranean origin)
• α-thalassaemia trait (usually children of African or Far Eastern origin)
• anaemia of chronic disease (e.g. due to renal failure).
Management
Ayesha, aged 2 years, was noted to look pale when she attended her general practitioner for an upper respiratory tract infection. A blood count showed Hb 5.0 g/dl, MCV 54 fl (normal 72-85 fl) and MCH 16 (normal 24-39 pg). She was drinking 3 pints of cow's milk per day and was a very fussy eater, refusing meat. She had started eating soil when playing in the garden.
Because of the inappropriately large volume of milk she was drinking, she was not sufficiently hungry to eat solid food. Replacing some of the milk with iron-rich food and treatment with oral iron produced a rise in the Hb to 7.5 g/dl within 4 weeks. Her pica (eating non-food materials) stopped.
Case History
22.1 Iron deficiency anaemia suggests a non-dietary cause or if there is failure to respond to therapy in compliant patients. Blood transfusion should never be necessary for dietary iron deficiency. Even children with an Hb as low as 2-3g/dl have arrived at this low level over a prolonged period and can tolerate it.
For most children management involves dietary advice and supplementation with oral iron. The best tolerated preparations are Sytron (sodium iron edetate) or Niferex (polysaccharide iron complex) - unlike some other preparations these do not stain the teeth. Iron supplementation should be continued for a minimum of 3 months to restore the Hb to normal and also to replenish the iron stores. With good compliance, the Hb will rise by about 1g/dl per week. Failure to respond to oral iron usually means the child is not getting the treatment. However, investigation for other causes, in particular malabsorption (e.g. due to coeliac disease) or chronic blood loss (e.g. due to Meckel's diverticulum) is advisable if the history or examination
Treatment of iron deficiency with normal Hb
Whether children who have a normal Hb but biochemical evidence of iron deficiency (e.g. low serum ferritin) should be treated with oral iron is controversial. In favour of treatment is the knowledge that iron is required for normal brain development and there is evidence that iron deficiency anaemia is associated with behavioural and intellectual deficiencies which may be reversible with iron therapy. However, it is not yet clear whether treatment of subclinical iron deficiency confers significant benefit. Treatment also carries a risk of accidental poisoning with oral iron, which is very toxic. A simple strategy is to provide dietary advice to increase oral iron and its absorption in all children with subclinical deficiency and to offer parents the option of additional treatment with oral iron supplements.
Treatment of iron deficiency anaemia is with dietary advice and oral iron therapy for
