Safety, Efficacy, and Feasibility of High-dose Cholecalciferol in Pediatric Patients With Cystic Fibrosis

Children and adults with Cystic Fibrosis (CF) are at risk of developing a vitamin D deficiency or insufficiency, defined as a 2,25-hydroxyvitamin D (25OHD) serum blood level <30 ng/dL. Greater than 85% of people with CF have pancreatic insufficiency, which contributes to poor absorption of fat soluble vitamins in addition to dietary fat. A 25OHD level greater than 30 ng/dL has been described as providing potential improvements to markers of inflammation in adults with CF and is known to improve bone mineral density and prevent bone fractures in all populations, including CF. This study will assess the safety of a one-time high dose of cholecalciferol or vitamin D3 along with the efficacy and feasibility.

Children between the ages of 3 years and 18 years (inclusive), with a 25OHD level <30 ng/dL will be provided with a vitamin D3 supplement of 250,000 international units (IU) observed in our CF clinic. We hypothesize that this one-time, oral, high dose of vitamin D3 will safely and effectively raise the 25OHD level to above 30 ng/dL.

Safety will be monitored with serum calcium levels 1 week following the dosage, since 25OHD has a half-life of 2-3 weeks and this serum calcium level measurement time-point would be in or near the middle of this range. Feasibility will be measured using a 5-question phone survey 1 week following the dosage (see appendix A - attached). Efficacy will be measured by the 25OHD level itself; if 25OHD levels are found to be between 30-100 ng/dL over the course of the study, the dose will have demonstrated effective in achieving the study's goal.

The purpose of this study is to show that 25OHD levels can be safely corrected with a one-time dose of vitamin D3 that can be safely and feasibly provided in the outpatient setting to children with CF.