Mean Platelet Volume Predicts Platelet Engraftment Post Hematopoietic Stem Cell Transplantation

The exact duration of thrombocytopenia after stem cell transplantation is difficult to predict. However, studies have shown that the presence of large platelets in the circulation may indicate enhanced platelet production in the bone marrow. The goal of this study was to characterize the relationship between mean platelet volume (MPV) and platelet count recovery in the setting of hematopoietic stem cell transplantation (HSCT) and to characterize how the MPV changes as the bone marrow recovers from the transient aplastic phase.

The data was collected by retrospective medical chart review of patients who underwent HSCT at Hahnemann University Hospital between 2007 and 2012. Platelet counts and MPV were obtained from day zero of transplantation until full platelet recovery. Platelet recovery was defined as the first day at which platelet count spontaneously exceeded 20,000/μL, increased consistently, and patients were free of platelet transfusion due to thrombocytopenia. Using the beginning of platelet recovery as a landmark day, the platelet counts were divided into four phases: aplastic phase, pre-recovery phase, early recovery phase, and full recovery phase. MPV during pre recovery and early recovery phase was compared with MPV during aplastic and full recovery phase. Mean, standard deviation (SD), median and range were obtained for age, platelet count, MPV, ANC, Hemoglobin, HCT and white count. Number of observations for gender, transplant, and graft were compared with Chi-squared test, and P-values were reported. Analysis of Variance (ANOVA) with post-hoc analysis was performed to compare MPV measurements between the phases. The level of significance was set at 0.05. Data entry and analysis was performed with SPSS (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp).

60 subjects were considered for the study, but 19 were excluded because the day of platelet recovery could not be determined from the available data. Of the 41 evaluable subjects, 22 were male and 19 female. The median age was 56 years (range 23 to 79). 34 patients (88%) underwent autologous and 7 allogeneic HSCT, with 36 getting peripheral stem cells (83%) and 5 getting marrow stem cells. Mean (SD) of MPV (fL) at aplastic, pre-recovery, early-recovery and full-recovery phases were 7.7 (0.67), 8.5 (0.88), 8.6 (0.88) and 7.4 (0.79), respectively. There was a statistically significant increase in MPV between the aplastic and pre-recovery phases (p<0.001), and between aplastic and early-recovery phases (p<0.001). The MPV then declined significantly between pre-recovery phase and full-recovery phase (p<0.001), and between early-recovery phase and full-recovery phase (p<0.001).

Our study demonstrated that MPV increased during the three-day period prior to start of platelet recovery. The rise in MPV was sustained during the early-recovery phase. The MPV then dropped back down when full platelet recovery was established. Our results show that spikes in MPV can be a useful marker of impending platelet engraftment within a few days of the rise in MPV. This information may be useful to determine the need for directed donor platelet collections.

No relevant conflicts of interest to declare.