The High Initial Dose of Monitored Vitamin D Supplementation in Preterm Infants.

Infants in the monitored group will receive an initial dose of 1000 IU of vit D. An additional 160 IU/kg of vit D is included in parenteral nutrition, as well as 150-300 IU/kg in enteral nutrition, depending on the amount and source of enteral feeding (i.e., human milk fortifiers or milk formula). At 28±2 days of age, blood samples will be obtained for 25(OH)D concentration measurement, followed by measurements every 4 weeks and/or 35±1 weeks of PCA. In the monitored group, vit D doses will be appropriately modified, based on 25(OH)D levels, using the scheme described in the Polish recommendation. The intake from the diet will be calculated from the second month of life.

Infants in the controlled group will receive 250 IU for very low birth weight infants and 500 IU for infants weighing above 1000 g. An additional 160 IU/kg of vit D is included in parenteral nutrition, as well as 150-300 IU/kg in enteral nutrition, depending on the amount and source of enteral feeding (i.e., human milk fortifiers or milk formula). Infants assigned to the standard therapy group will undergo the same blood sample collection procedure as the monitored group, but without any alterations in their dosing regimen.