Loukou I, et al. - Given that vitamin D status is considered a potential determinant of lung function in cystic fibrosis (CF), researchers examined the decline of spirometric values in association with vitamin D status. For this investigation, they retrospectively obtained the information regarding 25-hydroxy vitamin D (25OHD) serum levels, spirometric measurements (FEV1, FVC, FEF25-75%), and factors known to be linked to the decline of lung function in CF over a 5-year period. In patients with CF, vitamin D status is related to lung function. Levels of 25OHD above 20 ng/mL have been linked to higher best annual FEV1. No significant difference was found between patients with mean 5-year 25OHD levels ≥30 ng/mL and ≥20 to <30 ng/mL.