High-dose Cholecalciferol Supplementation in Adults with Cystic Fibrosis

Despite the availability of consensus guidelines for the treatment of vitamin D deficiency, prospective trials are lacking to examine alternative dosing strategies for adult patients with cystic fibrosis (CF) who do not meet therapeutic goals with standard regimens.

The primary objective of this study was to determine the efficacy of high-dose cholecalciferol supplementation in increasing serum vitamin D (25-OHD) levels in adult patients with CF.

Patients were eligible for inclusion if they were 18 years or older, had baseline 25-OHD levels lower than 30 ng/ml, and were diagnosed with CF and pancreatic insufficiency. Patients were given a single dose of cholecalciferol 300,000 or 500,000 IU based on baseline 25-OHD levels. Response was defined by 25-OHD and ionized calcium levels at 3 months. At 6 months, responders received a second dose of the same strength, and nonresponders were given a weekly supplement of cholecalciferol 50,000 IU in addition to cholecalciferol 500,000 IU. A second 25-OHD level was obtained at 9 months.

Of the 46 patients enrolled, 32 patients (70%) completed the study. Baseline levels of 25-OHD significantly increased over time in the per protocol population at 3 and 9 months. A total of 16 patients (50%) were considered nonresponders and required weekly supplementation.

A protocol using high-dose cholecalciferol or high-dose plus weekly cholecalciferol is safe and effective in treating adult patients with CF and pancreatic insufficiency.