'Normal' Mean Corpuscular Volume Does Not Exclude the Diagnosis of Thalassaemia

摘要

The mean corpuscular volume (MCV) measured by automated blood cell counter is a convenient way of recognising microcytosis which is a hallmark feature in the diagnosis of thalassaemic syndromes. Two children with severe thalassaemia syndrome but normal MCV measurements are described. A 17-month-old girl with homozygous b-thalassaemia and a 3-year-old girl with haemoglobin H-Constant Spring disease presented with anaemia. Results from the automated blood cell counter showed haemoglobin of 7.0 g/dL and 8.0 g/dL (normal, 11.0-15.0), respectively, with corresponding MCV of 80.5 fL and 79.3 fL (normal, 70.0-90.0), respectively. Microcytosis and hypochromia, however, were prominent on microscopic examination of the peripheral blood smear, which led to the correct diagnosis. Paediatricians and family physicians should be alerted to the potential pitfalls when interpreting the results provided by automated blood cell counters. Microscopic examination of the peripheral blood smear is indispensable in the evaluation of anaemic children.