Factors Affecting Immunoreactive Trypsinogen Levels in Cystic Fibrosis Newborn Screening

<bold>Introduction:</bold> Immunoreactive trypsinogen (IRT) is utilized in newborn screening for cystic fibrosis(CF). This study aims to investigate factors affecting IRT levels. <bold>Methods:</bold> Children admitted with elevated IRT levels at the pediatric pulmonology department between January 01, 2023-2024, were included. The control group comprised healthy children randomly selected from the outpatient pediatric department with normal IRT levels. Demographic and clinical data of Case(Group1) and Control Group(Group2) were retrospectively recorded and compared. <bold>Results:</bold> 76 children were included in Group1 and 77 in Group2. Median age at Group1 was 23.5 days, with 56.6% females. Three patients in Group1 had CF diagnosis. No difference between the groups in terms of age, gender and height z score (p>0.05). The mean weight z score of Group1 (−0.32±0.87) was lower than Group2 (p=0.031). Maternal smoking exposure during pregnancy, maternal chronic diseases, maternal parity and being the third or later-born child were higher in Group1 (p <0.05). In Group2 the number of babies with a birth weight over 4000 grams and a gestational age over 41 weeks was higher(p <0.05). No differences were found in hospitalization during the neonatal period, feeding methods, daily weight gain, maternal age, mode of delivery, birth season, consanguinity between parents and maternal abortion history between the two groups(p>0.05). Discussion:It may be recommended to increase the cut-off value for IRT/IRT in newborns with low birth weight, who were exposed to maternal smoking during pregnancy, whose mothers have a chronic disease and a history of three or more pregnancies. Larger studies will provide clearer insights into these associations