title: Measurement of reference intervals for urinary free adrenal steroid levels in Japanese newborn infants by using stable isotope dilution gas chromatography/mass spectrometry.
abstract: BACKGROUND
  In newborn infants, there are no reference intervals for urinary free steroids, which are thought to reflect the bioavailable fraction of steroids in the blood. We establish a method for simultaneous measurement of urinary free adrenal steroids such as pregnenolone, progesterone, 16α-hydroxyprogesterone, 17α-hydroxyprogesterone, 21-deoxycortisone, 21-deoxycortisol, dehydroepiandrosterone, androstenedione, and 11β-hydroxyandrostenedione by using stable isotope dilution gas chromatography/mass spectrometry (SID-GC/MS) and determined the reference intervals for urinary levels of free adrenal steroids in Japanese newborn infants.
  
  
  METHODS
  Newborn pooled urine was used for validation. Spot urine samples were collected from 67 full-term Japanese newborn infants (34 male and 33 female infants) at 3-4 days of age to determine reference intervals. The extracted and purified free steroids were delivered with heptafluorobutyric anhydride and analyzed by SID-GC/MS.
  
  
  RESULTS
  We validated a SID-GC/MS method with good repeatability and recovery rate. The preliminary reference intervals (median [range], μmol/mol creatinine) were as follows: pregnenolone, 4.2 (0.7-31.6); progesterone, 0.5 (not detected (n.d.)-0.6); 16α-hydroxyprogesterone, 1.4 (n.d.-10.3); 17α-hydroxyprogesterone, 1.1 (n.d.-1.9); 21-deoxycortisone, n.d. (n.d.-n.d.); 21-deoxycortisol, n.d. (n.d.-n.d.); dehydroepiandrosterone, 2.2 (0.6-27.3); androstenedione, 0.7 (n.d.-5.2); and 11β-hydroxyandrostenedione, 2.9 (n.d.-26.7).
  
  
  CONCLUSIONS
  We established a reliable SID-GC/MS method and were able to determine preliminary reference intervals for 9 urinary free adrenal steroids in newborn infants.
authors.affiliation: Department of Laboratory Medicine, Keio University School of Medicine, Tokyo 160-8582, Japan.
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Koyama
authors.forename: Keiko
authors.initials: K
authors.lastname: Homma
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miwa
authors.forename: Kazushige
authors.initials: K
authors.lastname: Ikeda
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Murata
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Hasegawa
mesh_terms: D000305:Adrenal Cortex Hormones / Q000652:urine*; D000311:Adrenal Glands / Q000378:metabolism*; D044466:Asian People; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010103:Oxygen Isotopes; D012015:Reference Standards; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000305:Adrenal Cortex Hormones; D010103:Oxygen Isotopes