Reticulocyte counting in thalassaemia.

The thalassaemias are a heterogeneous group of genetic haemoglobin disorders. The use of the Sysmex R- 1000 instrument in their study during the last 5 years has proved valuable. 1 Reticulocyte percentage and absolute counts were estimated in heterozygous beta-thalassaemia, in beta thalassaemia intermedia and in sickle beta thalassaemia and were compared with normal controls. Reticulocyte maturation subpopulations (high, middle and low fluorescence ratio) were assessed and compared with those of other haematological disorders. Red cell size and non-specific auramine-O binding were shown to be factors affecting mature red cell autofluorescence. 2 Nucleated red blood cells (NRBC) interfere with leucocyte counts in most haematology analysers. The upper particle count (UPP), provided by the R-1000 with modified fluorescence amplification voltage, appeared to produce a direct NRBC count in beta-thalassaemia intermedia when compared to NRBC counts assessed indirectly. 3 Erroneous platelet counts are reported by most haematology analysers in thalassaemia intermedia (especially in haemoglobin H disease) due to extensive microcyte-platelet interference and cause problems in diagnosis and management. Platelet counts provided by the R-1000 instrument in such patients were comparable to counts assessed by microscopy. Flow cytometric analysis by the Sysmex R-1000 instrument is useful in thalassaemia syndromes not only for providing precise reticulocyte counts and reticulocyte maturation data, but for direct NRBC counting and accurate platelet enumeration in cases of thalassaemia intermedia.