The objective of this study was to evaluate the effect of 2 different doses of vitamin D on the expression of T regulatory cells (Treg) in premature infants. A double-blind randomized controlled trial was conducted on preterm infants born with gestational age between 280/7 and 336/7 weeks. Subjects were randomly assigned to receive 400 or 800 IU/day of vitamin D3 when they achieved 100 mL/kg of enteral feeds. Percentage increase in Treg cell counts were measured by flow cytometry at enrollment, and after 1 and 4 weeks of oral vitamin D supplementation at the allotted doses in both groups. Short-term morbidity and mortality outcomes were also assessed. A total of 40 infants were enrolled, 20 in each group. The change in Treg count (%) was significantly less in the low-dose vitamin D3 supplementation group after 1 week (1.9 ± 5.5 vs 60 ± 5.6, P = 0.0005) and after 4 weeks (1.8 ± 5.7 vs 73.7 ± 5.6, P = 0.0028). The 2 groups did not differ in anthropometric measurements, duration of oxygen and respiratory support, and mortality. Length of hospital stay was longer in the low-dose group (24.9 ± 5.14 vs 22 ± 3.49, P = 0.04). Oral vitamin D supplementation has a dose and time dependent effect on percentage of Treg in infants born prematurely. The 800 IU dose of vitamin D3 did not have apparent short-term side effects. Larger studies are needed to explore the effect of vitamin D3 dosing on length of hospital stay.
*Department of Neonatology, Cleveland Clinic Children's, Cleveland, OH
†Department of Pediatrics, Faculty of Medicine, Cairo University
‡Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt.
Address correspondence and reprint requests to Hany Aly, MD, MSHS, FAAP, Cleveland Clinic Children's Hospital, 9500 Euclid Ave, M31-37, Cleveland, OH 44195 (e-mail: AlyH@ccf.org).
Received 3 April, 2019
Accepted 26 June, 2019
www.ClinicalTrials.gov registration number: NCT03793309.
The authors report no conflicts of interest.