Background: Airway inflammation starts in early life in cystic fibrosis (CF) and limited, objective markers are available to help identify infants with increased inflammation. We aimed to investigate neutrophil-lymphocyte ratio (NLR), mean platelet volume (MPV) and immunoreactive trypsinogen (IRT) as possible inflammatory biomarkers for cystic fibrosis in infancy.

Methods This was a retrospective cohort study in three centers. Between January 2015 and December 2022, children who were diagnosed with CF by newborn screening (NBS) were included in the study. Measures of NLR, MPV, and IRT at the time of NBS were correlated with follow-up measures:  z-scores for height weight, and body mass index (BMI), modified Shwachman-Kulczycki score (mSKS), and pulmonary function tests (PFTs).

Results A total of 92 children with CF were included in the study and 48% of them were female. There were no significant correlations between NLR or MPV, and weight or height z-scores for all ages, mSKS, or PFT findings at all ages(p>0.05); a negative correlation was found between MPV and BMI z-score at the age of 6 (r=-0.443, p=0.038). There was a negative correlation between the first IRT and BMI z-score at 6 years of age (r=-0.381, p=0.046) and negative correlations between the second IRT, and weight and BMI z-scores at the age of 6 (r=-0.462, p=0.010; r=-0.437, p=0.016, respectively).

Conclusion Higher MPV and IRT levels during the NBS period are associated with poor nutritional outcomes which may be due to chronic inflammation.