Interference of Hb-H disease in automated reticulocyte counting

Hb-H disease is a form of alpha-thalassemia commonly found in south-east Asia. In this condition, numerous Hb-H bodies are found in erythrocytes using reticulocyte staining preparations. This is the first study addressing the possible interference of Hb-H inclusions in automated reticulocyte counting. In this study, seven Hb-H disease samples were tested. Results obtained by the visual method and the Technicon H*3 automated method agreed relatively well. This was in contrast to the Coulter STKS automated method which generally gave lower results. Furthermore, when the incubation time was extended to 180 min in the Coulter STKS method, two Hb-H disease samples gave results several-fold higher than those obtained using the 60 min incubation time. These discrepant results were likely to have been caused by the analyser using the wrong threshold to separate reticulocytes and mature erythrocytes. High and low interference in Hb-H disease samples was observed in the Coulter STKS automated reticulocyte method. Laboratories should be aware of this potential problem, particularly when samples are from patients of Asian origin.