Time-course analysis of 3-epi-25-hydroxyVitamin D3 shows markedly elevated levels in early life, particularly from Vitamin D supplementation in preterm infants

Abstract

Background:An epimeric form of 25-hydroxyvitamin D 3 (25(OH)D 3) has recently been detected in clinical samples, with relatively high levels in infants. Little is known on 3-epi-25(OH)D 3 formation and physiological function. Our objective was to study dynamics of 3-epi-25(OH)D 3 formation during infancy.Methods:25(OH)D 3 and 3-epi-25(OH)D 3 levels were measured by liquid chromatography-tandem mass spectrometry in 22 preterm (aged 34-37 wk), 15 early preterm (aged <34 wk), and 118 term infants up to 2 y of age. All infants were prescribed vitamin D 400 IU/day after the first week of life.Results:At birth, 3-epi-25(OH)D 3 levels were 3 (1-7) nmol/l, <10% of total 25(OH)D 3. From the second week to 3 mo of age, both 25(OH)D 3 and 3-epi-25(OH)D 3 increased, with highest 3-epi-25(OH)D 3 contribution in early preterm infants (up to 55% of total 25(OH)D 3 vs. 36% in term infants, P < 0.0001). After 3 mo of age, 3-epi-25(OH)D 3 normalized to <10% in all infants.Conclusions:At birth, all infants showed low contribution of 3-epi-25(OH)D 3, increasing the week after starting vitamin D supplementation, until 3 mo of age. Highest levels of 3-epi-25(OH)D 3 were found in early preterm infants, supporting the hypothesis that hepatic immaturity plays a role in 3-epi-25(OH)D 3 formation.