There are many different causes of anaemia in children. Cut-off haemoglobin values for anaemia vary according to the patient's age (and sex in later years).

Classification of anaemia

In general, the causes of anaemia are classified as to whether they cause reduced red cell production, increased red cell destruction (haemolysis), or blood loss. Additionally, premature babies may also develop anaemia for a variety of reasons which come together as 'anaemia of prematurity'.

Causes of reduced red cell production include:

• Iron deficiency
• Folic acid deficiency
• B12 deficiency
• Red cell aplasia (e.g. parvovirus B19 infection)
• Chronic renal failure
• Chronic inflammation

Causes of increased erythrocyte destruction include:

• Glucose 6 phosphate dehydrogenase deficiency (G6PD)
• Hereditary spherocytosis (red cell membrane defect)
• Sickle cell disease
• Thalassemia
• Haemolytic disease of the newborn

Iron deficiency anaemia

• Iron deficiency anaemia is a relatively common cause of anaemia in infants and children.
• It can be caused by reduced iron intake, poor iron absorption and/or chronic blood loss (e.g., menstruation).
• Excessive ingestion of cow's milk can cause iron deficiency in infants due to its low iron content and the fact that it reduces iron absorption.