Local reference intervals for MacroR, MicroR, IG% and IG# on Sysmex XN-1000: A retrospective indirect LIS-based study

Extended complete blood count (CBC) parameters reported by Sysmex XN analyzers, such as microcytic red blood cell fraction (MicroR), macrocytic red blood cell fraction (MacroR), and immature granulocyte (IG) indices, are increasingly used in routine practice, yet locally validated reference intervals (RIs) remain limited for several of these measures. We aimed to derive RIs for MicroR, MacroR, immature granulocyte percentage (IG%), and immature granulocyte count (IG#) on the Sysmex XN-1000 using a laboratory information system (LIS)-based indirect approach. We analyzed routine LIS data from a tertiary-care university hospital and constructed a reference-candidate dataset using a predefined CBC-based selection workflow. After Tukey-based outlier assessment and visual review, extreme values inconsistent with the reference-candidate distribution were excluded. RIs were estimated by a nonparametric percentile method (2.5th-97.5th percentiles). Two-sided 90% confidence intervals for RI limits were obtained by bootstrap resampling (1000 iterations). Sex partitioning was assessed using the Harris-Boyd approach. The final reference sample group comprised 25,431 records (16,122 females; 9309 males). Median age was 47 years (interquartile range 33-57) in females and 45 years (interquartile range 31-57) in males. MicroR was reported as a pooled RI of 0.50% to 6.10%. MacroR required sex-specific reporting, with RIs of 3.60% to 5.20% in males and 3.30% to 4.60% in females. IG indices supported pooled reporting, yielding RIs of 0.01 to 0.04 × 109/L for IG# and 0.10% to 0.60% for IG%. Comparative analyses with published Sysmex XN-based studies placed these estimates within expected platform-specific patterns and highlighted that manufacturer limits may be unavailable for some extended parameters or may not fully reflect population-specific distributions. Using an indirect LIS-based workflow, we established local RIs for MicroR, MacroR, IG%, and IG# on the Sysmex XN-1000. These intervals provide practical local benchmarks for routine interpretation of extended CBC parameters; however, they should be interpreted in the context of an indirect LIS-based design without individual clinical verification.