RETICULOCYTE COUNTING IN THALASSEMIA

The thalassaemias are a heterogeneous group of genetic haemoglobin dis orders, The use of the Sysmex R-1000 instrument in their study during the last 5 years has proved valuable. 1 Reticulocyte percentage and ab solute counts were estimated in heterozygous beta-thalassaemia, in bet a thalassaemia intermedia and in sickle beta thalassaemia and were com pared with normal controls, Reticulocyte maturation subpopulations (hi gh, middle and low fluorescence ratio) were assessed and compared with those of other haematological disorders. Red cell size and non-specif ic auramine-O binding were shown to be factors affecting mature red ce ll autofluorescence. 2 Nucleated red blood cells (NRBC) interfere with leucocyte counts in most haematology analysers, The upper particle co unt (UPP), provided by the R-1000 with modified fluorescence amplifica tion voltage, appeared to produce a direct NRBC count in beta-thalassa emia intermedia when compared to NRBC counts assessed indirectly. 3 Er roneous platelet counts are reported by most haematology analysers in thalassaemia intermedia (especially in haemoglobin H disease) due to e xtensive microcyte-platelet interference and cause problems in diagnos is and management. Platelet counts provided by the R-1000 instrument i n such patients were comparable to counts assessed by microscopy. Flow cytometric analysis by the Sysmex R-1000 instrument is useful in thal assaemia syndromes not only for providing precise reticulocyte counts and reticulocyte maturation data, but for direct NRBC counting and acc urate platelet enumeration in cases of thalassaemia intermedia.