Establishment of reference interval for immature platelet fraction

Summary: Introduction: Immature platelet fraction (IPF) is a parameter for reticulated platelets. A high percentage IPF (%-IPF) is indicative of consumptive or recovering thrombocytopenic disorders in contrast to a low %-IPF seen in aplastic states. Absolute IPF (A-IPF) specifically reflects the number of immature platelets in circulation. This study aimed to establish reliable reference intervals for %-IPF and A-IPF. Methods: Except outliers, platelet counts and IPF were determined in 2152 healthy individuals (1252 men and 900 women) and 133 umbilical cord blood from healthy full-term neonates using XE-2100 hematology analyzer (Sysmex, Kobe, Japan). The reference intervals for %-IPF and A-IPF were defined using nonparametrical percentile methods according to the Clinical and Laboratory Standard Institute (CLSI) guideline. Results: Platelets,%-IPF, and A-IPF all showed nonparametrical distributions. In total individuals, the reference intervals for %-IPF and A-IPF were 0.5-3.3% (0.5-3.1% in men; 0.5-3.4% in women) and 1.25-7.02 × 10⁹/L (1.30-6.80 × 10⁹/L in men; 1.21-7.15 × 10⁹/L in women), respectively. The reference intervals for %-IPF and A-IPF in umbilical cord blood were 0.7-3.8% and 1.93-9.7 × 10⁹/L, respectively. Conclusions: This study provides the reference interval for IPF, including %-IPF and A-IPF, according to the CLSI guideline. These results could be used as fundamental data for clinical use as well as future researches.