Vitamin D deficiency is associated with pulmonary dysfunction in cystic fibrosis.

Background: Vitamin D deficiency is common in CF. Whether vitamin D affects pulmonary function in CF is unknown.

Methods: Data were abstracted from clinically stable CF patients who had pulmonary function studies and serum 25-hydroxyvitamin D [25(OH)D, ng/ml] levels drawn within 2 months of each other.