Iron Deficiency Anaemia

In early childhood the combination of a high demand for iron to keep up with rapid growth and a poor intake of iron-rich foods makes iron deficiency very common. This can be exacerbated by chronic blood loss induced by early exposure to whole cow’s milk. Iron deficiency anaemia can be as high as 50% in some populations, and in many countries young children are screened routinely. Babies beyond 12 months should be limited to 1 pint of milk (500 mL) daily to reduce blood loss and encourage the consumption of more iron-rich foods. Breast milk is somewhat protective as, although it has a relatively low iron content, the iron is absorbed more efficiently due to the iron binding protein, lactoferrin. However, exclusive breast-feeding beyond 6 months with delayed weaning can cause iron deficiency.

Iron deficiency anaemia is usually asymptomatic, but if the haemoglobin level falls significantly irritability and anorexia occur. Iron deficiency, even without anaemia, can affect attention span, alertness and learning. The initial finding is a low ferritin level reflecting inadequate iron stores. As the deficiency progresses microcytosis, hypochromia and poikilocytosis develop. Zn-protoporphyrin is high, as haem binds to zinc in the absence of iron. Treatment of iron deficiency is iron salts given orally for 2–3 months. The haemoglobin level starts to rise within 1 week of treatment. Failure to do so suggests non-compliance or an incorrect diagnosis. Patients should be warned that iron supplements make the stool turn black and that iron is dangerous in overdose. The medicines must be stored safely, away from toddlers.

Thalassaemia

The thalassaemias are a group of heritable hypochromic anaemias varying in severity, caused by a defect in haemoglobin polypeptide synthesis. Beta-thalassemia is the commonest, and affects Asian and Mediterranean individuals (1 in 7 Cypriots, 1 in 20 Indians). Overall, 3% of the world’s population carry the thalassaemia gene mutation.

Beta-thalassaemia trait (the heterozygous form) causes a mild hypochromic, microcytic anaemia, which may be confused with iron deficiency. Diagnosis is made by haemoglobin electrophoresis which demonstrates high levels of HbA2 and HbF. It requires no treatment. Alpha-thalassaemia trait (heterozygous) is suggested by a mild hypochromic microcytic anaemia with low or normal levels of HbA2 and HbF and no evidence of iron deficiency. It is important to recognize these conditions to avoid unnecessary iron treatment and to give patients advice that their own future children could be at risk of a more serious thalassaemia major disorder, so a future partner may need a thalassaemia screen.

Homozygous beta-thalassemia results in a severe haemolytic anaemia, with compensatory bone marrow hyperplasia producing a characteristic bossing of the facial and skull bones and leads to dental abnormalities. There is marked hepatosplenomegaly. Blood transfusions are required on a regular basis to maintain haemoglobin levels. Haemosiderosis due to iron overload is an inevitable consequence causing cardiomyopathy, diabetes and skin pigmentation, but can be minimized by continuous subcutaneous infusions of the chelating agent desferrioxamine (deferoxamine).

Sickle-Cell Anaemia

Sickle-cell anaemia is the commonest haemoglobinopathy, occurring in 1 in 4 West Africans and 1 in 10 Afro-Caribbean people. In sickle cell disease one of the amino acid sequences in the beta-globin chain is substituted, causing an unstable haemoglobin (HbS). When deoxygenated, this forms highly structured polymers making brittle spiny red cells which occlude blood vessels, causing ischaemia. Heterozygote carriers (sickle cell trait) are usually asymptomatic, but can experience problems during general anaesthesia. There are over 300 haemoglobinopathies and other forms of sickle cell disease include HbSC or Hb-beta-Thal, where the child is a compound heterozygote, inheriting HbS from one parent and HbC or beta-thalassaemia trait from the other.

In the homozygous condition children experience recurrent acute painful crises which can be precipitated by dehydration, hypoxia, infection or acidosis. Painful swelling of the hands and feet is a common early presentation. Repeated splenic infarctions eventually leave the child asplenic and therefore susceptible to serious infections. Pneumococcal vaccination and prophylactic penicillin is recommended. Renal damage leads to a reduced ability to concentrate urine, making dehydration a severe problem. Treatment of a crisis is largely symptomatic with analgesics, antibiotics, warmth and adequate fluid hydration.

The peripheral blood film typically shows target cells, poikilocytes and irreversibly sickled cells. Diagnosis is made by haemoglobin electrophoresis, which may also be used for screening in susceptible populations. Universal antenatal screening is now offered to mothers and the newborn blood spot is screened for abnormal haemoglobin.