Paediatric, age-specific reference intervals for reticulocyte count on Abbotts Alinity hq platform

Since haematopoiesis changes dramatically after birth and during childhood, specific paediatric reference intervals are critical for meaningful interpretation of haematological blood analyses. Paediatric reference intervals for reticulocyte count are not available for Abbott platforms. In this study, we used an indirect, data-mining approach with data from Abbott's Alinity hq platform to establish reticulocyte count reference intervals for children aged up to 18 years. Data were extracted from the 1^st of July 2021 to the 6^th of November 2024 and in order to find the 'healthiest patients', we included only reticulocyte counts from samples with normal haemoglobin and only samples from patients with a single reticulocyte count in the extraction period (n = 1633). We found relatively high reticulocyte counts in the first week of life (reference intervals for age 0-<7 days: 74-442 *10^9/L) and similar reticulocyte counts after this period and throughout childhood (reference interval for age 7 days-<18 years: 32-115 *10^9/L). In conclusion, this is the first study to report reference intervals for reticulocyte count in children using an Abbott platform. Compared to the literature, our reference intervals are higher than the reference intervals on other platforms, which is in line with reference intervals for adults, where Abbott also reports higher values compared to other platforms. The established reference interval for reticulocytes offers valuable insights for other laboratories using the Alinity hq platform and enhances the laboratory's ability to support clinical decision-making.