title: Differences in the urinary excretion of 6-beta-hydroxycortisol/cortisol between Asian and Caucasian women.
abstract: The urinary ratio of 6-beta-hydroxycortisol/cortisol has been used as a noninvasive probe for human cytochrome P450 3A4 isoforms (CYP3A4). Ethnic-related differences in the ratio have not been evaluated. The aim of this study was to determine if there are differences in the ratio between Asian and Caucasian women over a menstrual cycle. First-morning urine samples were collected every other day starting from the second day of menstruation for a complete menstrual cycle from 15 Asians and 16 Caucasian women who were 18 to 40 years old, healthy, nonsmoking, and alcohol and drug free, including oral contraceptives. Urine concentrations of 6-beta-hydroxycortisol and cortisol were measured by high-pressure liquid chromatography (HPLC). For statistical analysis, three phases of the menstrual cycle were evaluated: menstruation (days 1-4), follicular or postmenstruation (days 6-10), and the luteal phase (days 21-24) based on the average menstrual cycle (28 days). Statistical analysis was performed by an independent sample t-test using the Bonferroni correction for repeated measures. Large intersubject and intrasubject variations of the 6-beta-hydroxycortisol/cortisol ratios were observed during the menstrual cycles in both ethnic groups. Asian women had a statistically significant lower ratio than Caucasian women did for all three phases of the menstrual cycle: 2.2 +/- 1.1 versus 5.1 +/- 3.5, 2.1 +/- 1.1 versus 6.0 +/- 4.9, and 2.8 +/- 1.6 versus 5.6 +/- 3.0 for the menstruation, follicular, and luteal phases, respectively. The two- to threefold lower 6-beta-hydroxycortisol/cortisol ratios in Asian women suggest that Asian women may have a lower CYP3A activity compared with Caucasian women. Differences in ethnicity may mask potential gender-related effects if ethnic background is not evaluated as a contributing factor.
authors.affiliation: Department of Pharmacy, School of Pharmacy, University of Washington, Seattle 98195, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Lin
authors.forename: G D
authors.initials: GD
authors.lastname: Anderson
authors.forename: E
authors.initials: E
authors.lastname: Kantor
authors.forename: L M
authors.initials: LM
authors.lastname: Ojemann
authors.forename: A J
authors.initials: AJ
authors.lastname: Wilensky
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001208:Asia / Q000208:ethnology; D044466:Asian People; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000652:urine; D008597:Menstrual Cycle / Q000652:urine; D006899:Mixed Function Oxygenases / Q000378:metabolism; D044465:White People
chemical_list: C001380:6 beta-hydroxycortisol; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D006854:Hydrocortisone