URINARY MARKERS OF ESTROGEN METABOLISM 2-ALPHA-HYDROXYLATION AND 16-ALPHA-HYDROXYLATION IN PREMENOPAUSAL WOMEN

There is considerable scientific interest in whether measurement of th e major estrogen metabolites 2- and 16 alpha-hydroxyestrone will shed light on the role of estrogen in the risk of breast cancer. These have been difficult to measure in large numbers because of the need for ra diolabeled tracers, but a new assay is able to utilize spot urine samp les. The main objective of this study was to assess the reliability of a newly developed enzyme immunoassay (EIA) for the measurement of 2- and 16 alpha-hydroxyestrone in urine samples collected from a large gr oup of healthy premenopausal women enrolled in a clinical trial. A sec ondary objective was to assess the impact of several factors such as b ody weight on the urinary estrogen metabolite ratios. The study cohort included 174 women aged 44-50, who were enrolled in the Cardiovascula r Risk Factors and Menopause Trial, also referred to as the Women's He althy Lifestyle Project (WHLP), an ongoing 5-year clinical trial of 53 5 premenopausal women randomized either to an intensive dietary life-s tyle intervention group or to an assess ment-only control group. Measu rements of 2- and 16 alpha-hydroxyestrone showed a high intraclass cor relation for blind duplicate urine samples (R = 0.94 and R = 0.80), cr oss-sectionally and over lime (R = 0.79 and R = 0.62), in this populat ion of healthy premenopausal women. The intervention diet (of 25% of t otal calories from fat) did not appear to influence the estrogen metab olite ratio. This new estrogen metabolite EIA demonstrates good reliab ility and thus may be appropriate for use in large epidemiologic studi es of estrogen-related diseases. There was no relation between dietary fat reduction, weight loss, and increased exercise and change in the ratio among premenopausal women in this study.