Differences in the urinary excretion of 6-beta-hydroxycortisol/cortisol between Asian and Caucasian women

J Clin Pharmacol. 1999 Jun;39(6):578-82. doi: 10.1177/00912709922008182.


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.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Analysis of Variance
  • Asia / ethnology
  • Asian Continental Ancestry Group*
  • Cytochrome P-450 CYP3A
  • Cytochrome P-450 Enzyme System / metabolism
  • European Continental Ancestry Group*
  • Female
  • Humans
  • Hydrocortisone / analogs & derivatives*
  • Hydrocortisone / urine
  • Menstrual Cycle / urine
  • Mixed Function Oxygenases / metabolism


  • 6 beta-hydroxycortisol
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • CYP3A protein, human
  • Cytochrome P-450 CYP3A
  • CYP3A4 protein, human
  • Hydrocortisone