Pediatric reference intervals for hematology parameters in healthy infants and young children in Iran

Abstract Introduction Defining accurate age‐ and sex‐specific reference intervals (RIs) for hematology parameters, especially for the pediatric population, is important for making an appropriate clinical diagnosis. To address gaps, we established age‐specific RIs for 11 hematologic parameters in Iranian children younger than 30 months for the first time. Methods Fresh whole blood samples collected from a total of 344 participants (males: 158 and females: 186) ages 3 days to 30 months, with a mean age of 12.91 ± 7.15 months, were recruited from healthcare centers in Mashhad, Iran. Hematologic parameters, including complete blood count (CBC), were analyzed on the Sysmex auto‐analyzer system (KX‐21 N). RIs were calculated with 90% confidence intervals using the direct method based on CLSI Ep28‐A3 and C28‐A3 guidelines. Results None of the CBC parameters required sex partitioning. Of 11 CBC parameters, six required age partitions of 3 days–<4 months, 4–<10, 10–<15, and 4–<30 months. Five parameters (i.e., white blood cell count, mean corpuscular hemoglobin concentration, mean platelet volume, red cell distribution width, and platelet distribution width) did not demonstrate age‐specific changes. RIs of red blood cell count and hematocrit, as well as hemoglobin, increased with age, while mean corpuscular volume, mean corpuscular hemoglobin, and platelet count, decreased with age. Conclusion In this study, we established RIs for 11 hematology parameters in young children. Age partitioning was required for six parameters demonstrating marked changes during the early period of growth and development and necessitating the use of pediatric‐specific reference standards.