deficiency, and thalassaemia in preschool children

To investigate the possible causes of an increased incidence of red cell microcytosis in Asian children, 204 Gujarati Asian children and 88 European children attending community infant welfare clinics underwent initial screening tests for determination of red cell indices. Seventy six Asian (37%) and nine European (12%) children had microcytic red cells (mean corpuscular volume <74 fl). Further investigation showed that 16 of the Asian children (21%) with microcytosis had thalassaemia trait (eight were heterozygous for a thalassaemia and eight for 13 thalassaemia), and 50 (66%) had suspected iron deficiency (confirmed by a response to oral iron in 41 cases): the remaining 'microcytic' children were aged less than 2 years, when mean corpuscular volume between 70 and 74 fl may be normal. Increased values for serum total iron binding capacity were more sensitive in detecting iron deficiency than reduced serum ferritin concentrations. Enthusiastic screening for microcytic anaemia in young children may mean that a substantial minority with thalassaemia genes are given unnecessary iron supplements. The response to a short course of oral iron should therefore be carefully monitored, and the possibility of thalassaemia trait as well as non-compliance with treatment should be reconsidered in all those in whom there is little or no response. Northwick Park Hospital and MRC Clinical Research Centre, Harrow, Department of Paediatrics A Earley B Valman Section of Medical Statistics D G Altman Section of Haematology M J Pippard Correspondence to: Dr A Earley, Wycombe General Hospital, Queen Alexandra Road, High Wycombe, Bucks HP1I 2TT. Accepted 24 October 1989 A reduction in the size of red cells (microcytosis) has been reported more often in Asian than in European children of the same age in both community' and hospital2 studies. This finding has been attributed to a high incidence of dietary iron deficiency in Asian children, although heterozygous thalassaemia is a potential additional cause.2 3 Previous studies have not considered the possibility that a thalassaemia genes, which occur commonly in some groups,4 contribute to the observed reduction in red cell size. This is an important consideration, as there is increasing pressure to identify and treat iron deficiency in young children.5 This reflects growing concern about the possible non-haematological effects of a low iron concentration, even without obvious anaemiaespecially the deleterious effects on learning ability.'8 Without a therapeutic trial of iron, mild degrees of iron deficiency may be difficult to confirm in young children who have little or no iron stores,9 10 and in whom serum iron and transferrin saturation are significantly lower than in adults. " Microcytosis thus assumes added importance for suspecting iron deficiency in young children, but may lead to unnecessary treatment with iron supplements if there is a high incidence of unrecognised a thalassaemia in the population. In this community based study we have examined the relative contributions made by iron deficiency and thalassaemia genes, especially a thalassaemia trait, to microcytosis in a predominantly Hindu, Gujarati Asian population, compared with European children from the same area of north west London. Subjects and methods PLAN OF INVESTIGATION AND TREATMENT Venous blood samples of 5 ml or less were taken from 204 Asian and 88 European children after informed consent from a parent. All were apparently healthy children attending infant welfare clinics in Harrow for routine immunisation or developmental screening, and were aged between 6 months and 6 years. The children were recruited consecutively as they came to the clinic, excluding those whose parents did not want them to take part. We also excluded those who were taking preparations containing iron, and those who had febrile illnesses. Details of racial origin and whether the child's family was vegetarian were recorded. All samples were taken between 1000 and 1300, and were analysed the same day for haemoglobin concentration and red cell indices (Coulter S+IV), and within three days for serum iron and transferrin concentrations. Serum samples were stored at -20°C for measurement of ferritin. Microcytosis was defined as a mean corpuscular volume of <74 fl based on the lower limit for the mean cell volume reference range (mean (2 SD)) defined by Isaacs et al in a study of European children from the same locality.' It was recognised that this cut off value would include a small number of normal, mainly young children, as the mean cell volume and haemoglobin concentrations increase slightly during early childhood. 12 Because the haematological findings of a thalassaemia trait overlap with normal when only one of the four genes is deleted or non-functioning, we might have underestimated the prevalence of a thalassaemia by as much as 50% (DJ Higgs, personal communication). If the mean cell volume was <74 fl, haemoglobin (Hb) A2 was estimated; 13 thalassaemia trait was diagnosed if the percentage of HbA2 was greater than 3-5. In microcytic patients, iron deficiency was suspected if iron stores seemed to be lacking, as 610 group.bmj.com on June 24, 2017 Published by http://adc.bmj.com/ Downloaded from