Background: The C3 epimer of 25-hydroxi-vitamin D3 (Epi25OHD3) is present in the pediatric and adult population and varies according to age. If it measurement is clinically relevant and should be considered to classify Vitamin D status is still unknown.
Objective: To measure 25OHD3, 25-hydroxy-Vitamin D2 (25OHD2) and Epi25OHD3 and to compare them with PTH and calcemia.
Method: Subjects: Children between 5 and 8 years of age born very preterm (VPT: <32 weeks of gestation) and term (≥38 weeks of gestation).
Exclusion criteria: SGA (weight ≤−2 SD), multiple pregnancy, chronic and acute disease and use of oral corticosteroids.
Measurements: 25OHD2, 25OHD3 and Epi25OHD3 by mass spectrometry (LC-MS/MS). 25OHD3 status (ng/mL): deficient <20, insufficient 20-30, sufficient ≥ 30. Total 25OHD3: 25OHD3+ Epi25OHD3. Statistical test: U-Mann Whitney.
Results: Seventy seven (83%) of a total of 93 subjects (45% female) had detectable Epi25OHD3 concentrations and only 2 subjects 25OHD2. An association was found between Epi25OHD3 and 25OHD3 (r=0.57, P <0.0001), calcemia (r=0.84, P=0.005) and PTH (r=0.18, P <0.0001). Gestational age was correlated to Epi25OHD3 (r=0.265, P=0.011) and 25OHD3 (r=0.229, P=0.036). There were differences in the percentage of total Epi25OHD3/25OHD3 between very premature and term subjects (P=0.04). When adding the concentrations of Epi25OHD3 to those of 25OHD3 (25OHD3 total) the percentage of Epi25OHD3/total 25OHD3 in VPT and term children was different (9.7% and 10.6% respectively). Vitamin D status changed. When categorizing Vitamin D status using total 25OHD3, the percentage of children with deficiency dropped from 19.4% to 12.9%, with insufficient from 54.8% to 47%, those with a sufficient status raised from 25.8% to 39.8%.
Conclusion: At school age, term as well as very preterm children have detectable levels of Epi25OHD3. It is necessary to establish the physiological role of Epi25OHD3, since when considered to establish Vitamin D status, it changed in an important proportion of children. Including its measurement in routinely used immunoassays and their harmonization in this regard, could be relevant in the classification of Vitamin D status.
27 - 29 Sep 2018
European Society for Paediatric Endocrinology