Measurement of the Absolute Immature Platelet Number Reflects Marrow Production and Is Not Impacted by Platelet Transfusion

The ability to distinguish increased platelet destruction from platelet hypo-production is important in the care of patients with bone marrow failure syndromes and patients receiving high dose chemotherapy. The measurement of immature circulating platelets based on RNA content using an automated counter is now feasible. This study evaluated the impact of recent platelet transfusion on measurement of immature platelet parameters.

The immature platelet fraction (IPF) and absolute immature platelet number (AIPN) were measured using the Sysmex XE-5000 analyzer prior to and following platelet transfusion in 9 transfusion-dependent patients with marrow failure secondary to aplastic anemia, myelodysplasia or transplantation conditioning. IPF and AIPN were also measured serially over 5 days of storage in 3 plateletpheresis components collected from normal donors.

Platelet transfusion did not significantly change the mean AIPN in transfused patients. In contrast, IPF decreased significantly from 6.6 ±4.6% at day -1 to 2.3 ±1.4% at day 0 before returning to 4.3 ±2.3% at day +1. In the platelet component, AIPN and IPF% increased significantly over 5 days of storage, most likely due to an artifact of the staining and detection process for stored platelets, no longer detected in vivo once the platelets were transfused.

Platelet transfusion decreases the IPF due to the resultant increase in circulating platelet count. However, platelet transfusion does not change the circulating absolute immature platelet number (AIPN), validating this assay as a reflection of ongoing platelet production by the bone marrow in various clinical settings, regardless of proximity to platelet transfusion.

No relevant conflicts of interest to declare.