The immature platelet fraction: creating neonatal reference intervals and using these to categorize neonatal thrombocytopenias

Abstract

OBJECTIVE: The immature platelet fraction (IPF) is a laboratory measurement analogous to the reticulocyte count, but reflecting the thrombopoietic state. Similar to a reticulocyte count, it can be expressed as a percent (IPF% = percent of platelets that are immature) or as an absolute number per μl blood;the immature platelet count (IPC = IPF% × platelets per μl of blood). STUDY DESIGN: Using a retrospective analysis of de-identified data from non-thrombocytopenic neonates, we created reference intervals for IPF% and IPC. We then tested the value of these measurements for categorizing thrombocytopenic neonates. RESULTS: New charts display reference intervals for IPF% and IPC on the day of birth according to gestational age, and during the first 90 days after birth. Neonates with hyporegenerative varieties of thrombocytopenias (syndromes, small for gestational age, birth asphyxia) had lower IPF% and IPC than did neonates with consumptive thrombocytopenias (immune-mediated, infection, disseminated intravascular coagulation, necrotizing enterocolitis;both P < 0.0001). CONCLUSION: The new reference interval charts can be used to recognize abnormal IPFs. The IPF parameters can help clarify the kinetic mechanism responsible for thrombocytopenias in neonates.

Platelet Counting: Ugly Traps and Good Advice. Proposals from the French-Speaking Cellular Hematology Group (GFHC)

“…Despite the poor standardization and a lack of correlation between the young platelet fraction measurements among the different instruments (absence of reference method and the existence of different reference ranges for different instruments), these parameters are good indicators of thrombopoietic activity [20][21][22]. IPF absolute count has been proven as an indicator of platelet recovery after chemotherapy in pediatrics [23] and, thus, has been proposed as a tool to categorize neonatal thrombocytopenia [24] or to predict peripheral immune thrombocytopenia [25,26]. IPF increases in diseases when there is increased platelet destruction or consumption and decreases in bone marrow failure.…”

Pediatric hematology normal ranges derived from pediatric primary care patients

“…We have also reanalyzed the CBC and reticulocyte data obtained by the Intermountain Health Care group in infants 0 to 90 days old and published before, mostly in graphic form. [2][3][4] These neonatal data were obtained using the Sysmex XE-5000 and XT-4000i analyzers.…”

Defining Normal Healthy Term Newborn Automated Hematologic Reference Intervals at 24 Hours of Life

“…6,[28][29][30][31] Since a left shift can be present at birth, it is difficult to determine what is abnormal in the absence of a wellestablished normal RI for IG% and absolute IG count. To develop RIs that are representative of the normal newborn population, Wiland et al 6 , Nigro et al, 29 and MacQueen et al 32 looked independently at samples of newborns considered noninfected by excluding those with positive blood cultures or ''clinical sepsis charted by the physician.'' From these presumptions, Wiland et al 6 established the IG% at 5.2% and MacQueen 32 established the upper limit for IG% at 6.2% during the first 48 HOL.…”

“…Our study identifies an IG% of up to 6.1% at 24 HOL as normal, which correlates with the study of MacQueen and colleagues. 32 Reticulocytes and Immature Reticulocytes.-Red blood cells (RBCs) mature from committed stem cells in the bone marrow by progressing from NRBCs, to reticulocytes, to mature RBCs. After the nucleus is extruded, the reticulated RBC contains residual RNA that is lost during the first 24 hours after it has been released into the peripheral blood.…”