title: Serum levels of 3-epi-25-OH-D3 during hypervitaminosis D in clinical practice.
abstract: BACKGROUND
  Intoxication from vitamin D supplements has been rarely reported, but nowadays, it occurs more frequently. The presence of the C-3 epimer of 25-hydroxyvitamin D(3) (3-epi-25-OH-D(3)) is highly prevalent in adults, although there is little information regarding its in vivo relevance, if any, especially under pathological conditions.
  
  
  OBJECTIVE
  Our aim was to assess the presence of the 3-epi-25-OH-D(3) in serum samples displaying 25-OH-D(3) concentrations indicative of hypervitaminosis D.
  
  
  METHODS
  A total of 58 samples displaying a wide range of concentrations of 25-OH-D(3) (>64-439 ng/ml) by ultrafast liquid chromatography were consecutively recruited and reassessed for the presence of 3-epi-25-OH-D(3) using a second chromatographic system. Data from additional biochemical tests performed as part of the patient evaluation were also recorded.
  
  
  RESULTS
  Mean relative contribution of 3-epi-25-OH-D(3) was less than 4%, and concentrations ranged from 2-28.6 ng/ml. Serum levels of the C3 epimer, but not the relative contribution, correlate with serum 25-OH-D(3). Overall, in subjects with 25-OH-D(3) concentrations indicative of hypervitaminosis D, the presence of the C-3 epimer and its levels were apparently unrelated to age, serum markers of renal and liver function, acute-phase reactants, and the presence of hypercalcemia. 3-Epi-25-OH-D(3) did not correlate with PTH, but subjects displaying PTH suppression (<14 pg/ml) showed higher concentrations of 3-epi-25-OH-D(3).
  
  
  CONCLUSIONS
  The relative contribution of 3-epi-25-D(3) was not significantly altered during hypervitaminosis D, although the absolute levels reached in serum may be biologically relevant. From a clinical viewpoint, although the small size of the group may affect the lack of relationships, the presence of 3-epi-25-OH-D(3) was apparently unrelated to serum markers of renal and liver function, acute-phase reactants, PTH, and the presence of hypercalcemia.
authors.affiliation: Unidad de Vitaminas, Servicio de Bioquímica Clínica, Peine 7 (Planta 1), Hospital Universitario Puerta de Hierro-Majadahonda, c/ Joaquín Rodrigo, 2, 28222 Majadahonda, Spain. fgranado.hpth@salud.madrid.org
authors.forename: F
authors.initials: F
authors.lastname: Granado-Lorencio
authors.forename: I
authors.initials: I
authors.lastname: Blanco-Navarro
authors.forename: B
authors.initials: B
authors.lastname: Pérez-Sacristán
authors.forename: E
authors.initials: E
authors.lastname: Donoso-Navarro
authors.forename: R
authors.initials: R
authors.lastname: Silvestre-Mardomingo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001774:Blood Chemical Analysis; D002112:Calcifediol / Q000031:analogs & derivatives / Q000032:analysis / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009748:Nutrition Disorders / Q000097:blood* / Q000628:therapy; D009994:Osmolar Concentration; D011364:Professional Practice; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism*
chemical_list: D014807:Vitamin D; D002112:Calcifediol