Reductions in urinary collection frequency for assessment of reproductive hormones provide physiologically representative exposure and mean concentrations when compared with daily collection.

OBJECTIVE To determine if reducing the frequency of urinary sample collection from daily to 5, 3, or 2 days per week during a menstrual cycle or 28-day amenorrheic monitoring period provide accurate representations of the reproductive hormone metabolites estrone-1-glucuronide (E1G) and pregnanediol glucuronide (PdG) exposure and mean concentrations. METHODS Exercising women presenting with eumenorrhea or exercise-associated menstrual disturbances collected daily urine samples for the assessment of E1G and PdG concentrations. After enzyme immunoassay analysis of the daily samples, E1G and PdG data were systematically removed from each menstrual cycle or amenorrheic monitoring period to mimic three reduced collection frequencies, representing 5, 3, and 2 days per week. Exposure and mean concentration were calculated for both hormones and all four urinary collection frequencies. RESULTS E1G and PdG exposure and mean cycle concentrations derived from reduced collection frequencies were not different from daily collection (P > 0.05), independent of whether menstrual cycles and monitoring periods were analyzed together or separately. Bland-Altman analysis indicated acceptable agreement between each reduced collection frequency and daily collection. CONCLUSIONS Compared with daily urinary collection, a reduced collection frequency of 5, 3, or 2 days each week provides accurate E1G and PdG profiles of collection periods of various lengths and types of menstrual function. Reduction of urinary sample collection frequency may enable researchers to reduce participant burden and costs, increase compliance, and study a wider range of study populations.