Vitamin D status in children with cystic fibrosis. Associations with inflammation and bacterial colonization.

RATIONALE: Patients with cystic fibrosis (CF) have high rates of vitamin D insufficiency. The relation between vitamin D status and inflammation in patients with CF is poorly understood.

OBJECTIVES: To determine the prevalence of vitamin D deficiency and insufficiency in a young CF population and to examine correlations between vitamin D status, disease severity, and inflammatory markers.

METHODS: This was a retrospective chart review of patients with CF under the age of 12 years. Serum laboratory parameters, growth indices, pancreatic status, CFTR genetics, medications, microbiology, and presence of CF-related comorbidities were collected for patients who had fat-soluble vitamin levels measured between January 1, 2009 and December 31, 2011. Vitamin D deficiency was defined as a serum 25(OH)D less than 20 ng/ml and insufficiency as serum 25(OH)D 20 to 29.9 ng/ml. Associations between serum vitamin D concentration and clinical/inflammatory markers were assessed using Chi-square and t tests.

MEASUREMENTS AND MAIN RESULTS: Data were collected for 148 children. The mean serum 25(OH)D concentration was 32.4 ng/ml (SD, 8.9). Seven percent (10 of 148) were vitamin D deficient, and 36% (53 of 148) were vitamin D insufficient. Among the pancreatic-sufficient patients, 50% (14 of 28) were vitamin D insufficient/deficient, whereas among pancreatic-insufficient patients, 41% (49 of 120) were vitamin D insufficient/deficient. Pseudomonas aeruginosa was a more common pathogen in the patients who were vitamin D insufficient/deficient (18 of 63 vs. 11 of 85, P = 0.018). There was no difference between vitamin D-sufficient versus -insufficient groups in terms of other bacterial colonization or inflammatory markers.

CONCLUSIONS: Overall, vitamin D insufficiency is common among young children with CF. Vitamin D insufficiency is prevalent even in children who are pancreatic sufficient. In this population, vitamin D insufficiency is associated with a history of Pseudomonas colonization but not with classic markers of systemic inflammation.