Screening for thalassaemia using the width of the Technicon H6000/H601 erythrocyte size histograms.

The red cell distribution width (RDW) calculated from the data of an erythrocyte size distribution (ESD) histogram generated by a Technicon H6000/H601 blood cell analyser was shown to be not suitable for distinguishing iron deficiency from thalassaemia trait and other microcytic conditions. The absolute distribution width at half maximum (ADW0.5) of these ESD histograms can be used efficiently for screening on thalassaemia trait. The ADW0.5 values appeared to be more powerful for detecting alpha thalassaemia and beta thalassaemia trait than the decision algorithms described earlier. A decreased MCV combined with a small ADW0.5 offers an indication of thalassaemia trait, the diagnosis being later confirmed by more definitive methods. By utilizing the ADW0.5, the number of subjects with thalassaemia trait, particularly those with alpha thalassaemia, detected in the south of The Netherlands was highly increased.