Vitamin D deficiency is associated with pulmonary dysfunction in cystic fibrosis

Abstract 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 2months of each other. Findings were adjusted for multiple variables known to affect pulmonary function in CF. Results Enrollees totaled 597. Overall mean 25(OH)D level was 29.6±12.8ng/ml (SD). Serum 25(OH)D levels showed a significant correlation with forced expiratory volume in 1s (FEV 1 ) % predicted ( r =0.20, p r =0.13, p=0.0019). Multivariate analysis revealed that serum 25(OH)D remained an independent predictor of FEV 1 % predicted even after controlling for multiple other factors known to affect CF lung function. Conclusions Serum 25(OH)D levels are significantly associated with pulmonary function in CF. Further study is required to determine whether this association is causal.