title: Quantitative determination of estradiol fatty acid esters in human pregnancy serum and ovarian follicular fluid.
abstract: BACKGROUND
  Lipophilic estradiol derivatives carried by lipoprotein particles in blood may mediate antioxidant or endocrine effects. We developed a new quantitative method to determine the concentration of circulating lipophilic estradiol fatty acid esters in human early- and late-pregnancy serum and in ovarian follicular fluid.
  
  
  METHODS
  After extraction from serum or follicular fluid, estradiol fatty acid esters were separated from nonesterified estradiol by Sephadex LH-20 column chromatography. The estradiol ester fraction was hydrolyzed by saponification and further purified by several chromatographic steps. The hydrolyzed estradiol esters were measured by time-resolved fluoroimmunoassay.
  
  
  RESULTS
  The average estradiol fatty acid ester concentration in serum increased 10-fold during pregnancy, from 40.4 pmol/L (expressed as pmol/L estradiol; range, 25.0-64.2 pmol/L) in early pregnancy (n = 8) to 404 pmol/L (196-731 pmol/L) in late pregnancy (n = 10). The ratio of estradiol ester to nonesterified estradiol remained relatively constant during pregnancy, at 0.4-0.6%. In 10 follicular fluid samples, the mean estradiol ester concentration was 106 nmol/L (56.9-262 nmol/L). Compared with serum, a greater proportion of estradiol in follicular fluid (3.0-10%) was in the esterified form.
  
  
  CONCLUSIONS
  The new method provides a means to measure circulating estradiol fatty acid ester concentrations in human pregnancy serum.
authors: Department of Medicine, PB 340, Helsinki University Central Hospital, 00290 Helsinki, Finland.
authors: V
authors: V
authors: Vihma
authors: H
authors: H
authors: Adlercreutz
authors: A
authors: A
authors: Tiitinen
authors: P
authors: P
authors: Kiuru
authors: K
authors: K
authors: Wähälä
authors: M J
authors: MJ
authors: Tikkanen
mesh_terms: D004952:Esters; D004958:Estradiol / Q000031:analogs & derivatives* / Q000032:analysis* / Q000097:blood; D005227:Fatty Acids; D005260:Female; D015200:Fluoroimmunoassay; D006801:Humans; D008297:Male; D006080:Ovarian Follicle / Q000737:chemistry*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011263:Pregnancy Trimester, Third; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D004952:Esters; D005227:Fatty Acids; D004958:Estradiol