S-25-hydroxyvitamin D and C3-epimers in pregnancy and infancy: An Odense child cohort study

Nanne Dreier Mydtskov, Sine Lykkedegn, Palle Back Nielsen Fruekilde, Jan Nielsen, Torben Barington, Henrik Thybo Christesen

Research output: Contribution to journalJournal articleResearchpeer-review


BACKGROUND: Analysis of serum 25-hydroxyvitamin D (s-25(OH)D) may be complicated by the less active or in-active vitamin D metabolite C3-epi-25(OH)D 3 (C3-epimer). We aimed to explore the relationship between s-C3-epimer and s-25(OH)D and other determinants and describe the longitudinal course of the C3-epimer fraction in paired mother-child samples.

METHOD: S-25(OH)D and s-C3-epimer were estimated by liquid chromatography mass spectrometry in 290 mother-infant pairs from the population-based Odense Child Cohort. Longitudinal analyses were feasible in two subcohorts; B) early and late pregnancy, cord, three and 18months (n=132); and C) early and late pregnancy, delivery and cord (n=105).

RESULTS: Mean s-25(OH)D was 50.6-110.4nmol/L at the six time points. The mean C3-epimer fraction was 10.1% at three months, 1.1%-3.0% at the other time points. In multivariate analyses, the s-C3-epimer correlated with s-25(OH)D (all time points, p<0.001), and season, maternal and infant age and maternal vitamin D supplementation at some time points. The C3-epimer fraction fluctuated between adjacent time points. By cosinor analyses, a season-dependent sinusoidal pattern for s-25(OH)D and C3-epimer fraction was found and changes between adjacent time points depended on season (p<0.007 or trend). In early infancy, subtraction of the C3-epi-25(OH)D 3 from total s-25(OH)D resulted in reclassification of 8% of the children by use of the 75nmol/L cut off for s-25(OH)D.

CONLCUSION: The s-C3-epimer was independently correlated to s-25(OH)D, season, maternal vitamin D supplementation, maternal and infant age. The C3-epimer fraction was only of clinical importance in early infancy, where it could lead to misclassification of the vitamin D status.

Original languageEnglish
JournalClinical Biochemistry
Issue number18
Pages (from-to)988-996
Publication statusPublished - Dec 2017


  • Journal Article
  • LC-MS/MS
  • Maternal
  • C3-epi-25-hydroxyvitamin D
  • Infant
  • Cord
  • 25-Hydroxyvitamin D
  • Humans
  • Child, Preschool
  • Male
  • Calcifediol/metabolism
  • Fetal Blood/metabolism
  • Pregnancy
  • Tandem Mass Spectrometry
  • Vitamin D Deficiency/blood
  • Chromatography, Liquid
  • Female
  • Vitamins/blood
  • Child
  • Dietary Supplements
  • Hydroxycholecalciferols/blood
  • Vitamin D/analogs & derivatives
  • Cohort Studies


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