International Journal of Laboratory Hematology The Official journal of the International Society for Laboratory Hematology
LETTER TO THE EDITOR
INTERNAT IONAL JOURNAL OF LABORATO RY HEMATO LOGY
Letter to the Editor
Reference intervals for immature platelet fraction and immature platelet count Sir, The recovery of platelet count is often used as an indicator of thrombopoiesis recovery after chemotherapy or hematopoietic progenitor cell transplantation. Flow cytometry has been used to follow the return of thrombopoiesis by identifying reticulated platelets [1]. This technique requires expensive instrumentation and manual manipulation and is very time-consuming and not readily available in all laboratories. The XE-2100/XE5000 hematology analyzer measures immature platelet fraction (IPF), an FDA-approved parameter with good correlation to flow cytometric detection of reticulated platelets [2]. The IPF technique uses a dye containing polymethine and oxazine which stains platelet RNA. Immature platelets contain more RNA than mature platelets and thus can be readily identified. The advantages of using an automatic hematology analyzer include ready availability, automation, and lower cost. The IPF has been used in a number of pediatric studies including hematopoietic recovery postchemotherapy
or hematopoietic progenitor cell transplantation and has been used in identifying acute and chronic idiopathic immune thrombocytopenia [3–5]. Many of these studies, however, were performed using the actual IPF level or IPC results. Because many hematopoietic indicators demonstrate age-specific changes, we hypothesized that IPF and immature platelet count (IPC) would also be age specific. Leftover CBC specimens from patients with normal platelet count were analyzed for IPF, using the XE-5000 hematology analyzer (Sysmex, America, Lincolnshire, IL, USA) per manufacturer’s recommendation. IPC was derived using the IPF value multiplied by the platelet count. Stratification was performed using previously defined age intervals [6] except that the samples for patients less than 180 days were aggregated. Within each stratification (both male and female), the Hoffmann approximation was utilized to establish 2.5th and 97.5th percentiles [7]. Details of the analysis are described in the legend for Table 1. IPF was much higher for both males and females
LETTER TO THE EDITOR
INTERNAT IONAL JOURNAL OF LABORATO RY HEMATO LOGY
Letter to the Editor
Reference intervals for immature platelet fraction and immature platelet count Sir, The recovery of platelet count is often used as an indicator of thrombopoiesis recovery after chemotherapy or hematopoietic progenitor cell transplantation. Flow cytometry has been used to follow the return of thrombopoiesis by identifying reticulated platelets [1]. This technique requires expensive instrumentation and manual manipulation and is very time-consuming and not readily available in all laboratories. The XE-2100/XE5000 hematology analyzer measures immature platelet fraction (IPF), an FDA-approved parameter with good correlation to flow cytometric detection of reticulated platelets [2]. The IPF technique uses a dye containing polymethine and oxazine which stains platelet RNA. Immature platelets contain more RNA than mature platelets and thus can be readily identified. The advantages of using an automatic hematology analyzer include ready availability, automation, and lower cost. The IPF has been used in a number of pediatric studies including hematopoietic recovery postchemotherapy
or hematopoietic progenitor cell transplantation and has been used in identifying acute and chronic idiopathic immune thrombocytopenia [3–5]. Many of these studies, however, were performed using the actual IPF level or IPC results. Because many hematopoietic indicators demonstrate age-specific changes, we hypothesized that IPF and immature platelet count (IPC) would also be age specific. Leftover CBC specimens from patients with normal platelet count were analyzed for IPF, using the XE-5000 hematology analyzer (Sysmex, America, Lincolnshire, IL, USA) per manufacturer’s recommendation. IPC was derived using the IPF value multiplied by the platelet count. Stratification was performed using previously defined age intervals [6] except that the samples for patients less than 180 days were aggregated. Within each stratification (both male and female), the Hoffmann approximation was utilized to establish 2.5th and 97.5th percentiles [7]. Details of the analysis are described in the legend for Table 1. IPF was much higher for both males and females
