In patients with cystic fibrosis (CF), the use of a novel vitamin D protocol has been associated with a rise in vitamin D levels and a reduction in the proportion of individuals with vitamin D insufficiency, according to findings from a multicenter, prospective, nonrandomized, uncontrolled experimental study published in Anales de Pediatría.

Recognizing that vitamin D deficiency is common among patients with CF, the researchers sought to establish the efficacy of a new vitamin D supplementation protocol based on consensus guidelines from the US Cystic Fibrosis Foundation (CSF) and the European Society of Cystic Fibrosis. These guidelines contain recommendations on the nutritional management of individuals with CF, including vitamin D supplementation.

The current study was conducted in 6 hospitals in Spain to evaluate the response to the protocol in study participants with CF and insufficient or deficient vitamin D levels. According to the CSF, treatment of vitamin D deficiency should involve trimestral increases in the daily vitamin D dose up to a maximum of 10,000 IU per day.

All enrolled patients had a diagnosis of CF, were clinically stable (ie, no fever, cough, expectoration, hemoptysis, or antibiotic therapy in the previous 2 weeks), had exocrine pancreatic insufficiency (stool elastase <200 μg/g), and exhibited insufficient 25-hydroxyvitamin D (25-OH-D) levels (<30 ng/mL).

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All patients were recruited between 2014 and 2016, with their initial visit occurring for selection purposes. Participants received vitamin D3 supplementation based on CSF consensus guidelines.

Follow-up visits for clinical and laboratory evaluations were performed at 3, 6, and 9 months (visits 1, 2, and 3, respectively), during which the participant’s vitamin D doses were modified according to measured serum levels. The aim was to maintain 25-OH-D levels in the range of 30 to 100 ng/mL. At the 1-year follow-up visit, participants with 25-OH-D levels greater than 100 ng/mL or symptoms of hypercalcemia were withdrawn from the study.

Thirty participants completed the follow-up. The median age was 9.05 years (range, 3.76-15.62 years). Half of the participants were male.

The results of the study showed a statistically significant increase in the mean vitamin D dose from the initial visit to the fourth visit (1837 vs 3165 IU/day, respectively; P <.001). In addition, a 7.6 ng/mL increment in mean 25-OH-D levels was reported during this time period (22.12 vs 29.75 ng/mL, respectively; 95% CI, 4.6-10). Further, a positive correlation was observed between the increase in vitamin D dose given and the elevated vitamin D levels observed between the same visits (P =.045).

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Overall, 37% of participants attained vitamin D levels of 30 ng/mL or more, 50% achieved levels between 20 and 30 ng/mL, and 13% continued to have levels of less than 20 ng/mL.

The authors concluded, “The proposed protocol achieved an increase in serum [vitamin D] levels and a decrease in the percentage of patients with [vitamin D] insufficiency, although it was still far from reaching the percentages of sufficiency recommended for this entity.”


Mangas-Sánchez C, Garriga-García M, Serrano-Nieto MJ, et al. Safety and efficacy of a new supplementation protocol in patients with cystic fibrosis and vitamin D deficiency. An Pediatr (Engl Ed). Published online March 15, 2023. doi:10.1016/j.anpede.2023.02.015