Quantitative determination of estradiol fatty acid esters in human pregnancy serum and ovarian follicular fluid.
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.
Vihma
V
V
Department of Medicine, PB 340, Helsinki University Central Hospital, 00290 Helsinki, Finland.
Adlercreutz
H
H
Tiitinen
A
A
Kiuru
P
P
Wähälä
K
K
Tikkanen
M J
MJ
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
D004952:Esters; D005227:Fatty Acids; D004958:Estradiol