Discriminating the endogenous and exogenous urinary estrogens in human by isotopic ratio mass spectrometry and its potential clinical value.

Estrogens were prohibited in the food producing animals by European Union (96/22/EC directive) and added to the Report on Carcinogens in United States since 2002. Due to very low concentration in serum or urine (similar to pg/mL), the method of control its abuse had not been fully developed. The endogenous estrogens were separated from urines of 18 adult men and women. The exogenous estrogens were chemical reference standards and over the counter preparations. Two patients of dysfunctional uterine bleeding (DUB) administered exogenous estradiol and the urines were collected for 72 h. The urinary estrogens were separated by high-performance liquid chromatography (HPLC) and confirmed. The exogenous and exogenous estrogens were analyzed by gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) to determine the C-13/C-12 ratio (delta C-13 parts per thousand). The delta C-13 parts per thousand values of reference standard of El, E2, and E3 were -29.36 +/- 0.72, -27.98 +/- 0.35, -27.62 +/- 0.51, respectively. The delta C-13 parts per thousand values of the endogenous El, E2, and E3 were -21.62 +/- 1.07, -22.14 +/- 0.98, and -21.88 +/- 1.16, with P < 0.01 (t-test). Two DUB patients' urinary estradiol delta C-13 parts per thousand values was depleted to -28.02 +/- 0.33 after the administration. The progesterone, 17 alpha-hydroxyprogesterone, pregnanediol, as well as desogestrel and ethinylestradiol from contraceptives were also determined. Stable carbon isotope analysis can distinguish the endogenous and exogenous urinary estrogen in human. (C) 2012 Elsevier Inc. All rights reserved.