Oliveira MS, et al. - In this investigation, researchers assessed vitamin D levels and severity of lung disease in infants and preschoolers diagnosed with cystic fibrosis (CF) and compared them to a group of children without pancreatic insufficiency (PI). They included patients with CF up to 4 years old and compared to an age-matched group of children without a diagnosis of CF. In this study, 45 patients in the CF group and 102 in the non-CF group were included, with no differences in age between them. No association was found between lung disease severity and vitamin D levels in CF group. Findings revealed that supplementation and seasonality were associated with higher vitamin levels.