Why and how to measure urinary sex steroid metabolites in epidemiological studies in women.

BACKGROUND AND AIM: Although numerous investigations have evaluated the association between urinary hormone levels and chronic diseases such as breast cancer and coronary heart disease, there are few data about the reliability of urinary measurements, particularly among premenopausal women. METHODS AND RESULTS: Over a six-month period, levels of estrone-3-glucuronide and pregnandiol-3-glucuronide were measured in both morning spot and overnight urine samples from seven healthy premenopausal women (ages 33-46). During this period, each subject provided one morning spot urine sample and one overnight urine sample per menstrual cycle on the same day of her menstrual cycle. All these samples were taken out of the freezer simultaneously and sent in the same parcel on dry ice to the laboratory for hormone determinations. All samples from each person were assayed simultaneously in the same run and by the same laboratory technician in a blind fashion. The intraclass correlation coefficients (ICC) for estrone-3-glucuronide and pregnandiol-3-glucuronide for the morning spot and overnight urine samples were 0.78 and 0.46 and 0.75 and 0.64 respectively. CONCLUSIONS: These data suggest that morning spot urine determinations are reliable and constitute an efficient alternative to the more complex overnight urine collection for epidemiological evaluation of urinary hormonal profiles.