Hypovitaminosis D in patients with cystic fibrosis: a cross-section study in South Brazil

Introduction: Cystic fibrosis (CF) patients have a susceptibility to vitamin D deficiency because of nutrient malabsorption. Objectives: To evaluate the prevalence of hypovitaminosis D in CF patients and the factors associated with serum 25-hydroxyvitamin D levels. Methods: We evaluated the prevalence of vitamin D deficiency defined as 25-hydroxyvitamin D <30 ng/mL, as suggested recently by the Cystic Fibrosis Foundation, and factors associated with its serum levels. Patients with confirmed CF were included. Nutritional status and hospital admissions were evaluated. Serum C-reactive protein, calcium, phosphate, magnesium, albumin, 25-hydroxyvitamin D and parathyroid hormone levels were measured. Lung function was evaluated by spirometry, and clinical and chest radiographic scores were assessed. Statistical significance level was set at P < 0.05. Results: Fifty-nine patients were included. Prevalence of hypovitaminosis D was 61%. Patients with pancreatic insufficiency had a trend to have higher vitamin D levels. Sixteen patients had severe lung disease with percentage of forced expiratory volume in 1 s predicted below 40%. After multivariate analysis, body mass index and hospitalization in the last month remained significantly associated with serum vitamin D levels. Conclusions: Vitamin D insufficiency is still a problem in CF patients, even in those receiving supplementation.