Direct radioimmunoassay of urinary estrogen and pregnanediol glucuronides during the menstrual cycle

Assays measuring immunoreactive estrone glucuronide (E1G), estradiol-3-glucuronide (E2-3G), estradiol-17β-glucorine (E2-17G), estriol-3-glucuronide (E3-3G), estriol-16αλucuronide (E3-16G), and pregnanediol-3α-glucuronide (Pd-3G) directly in diluted urine were developed and validated. These etrogen and pregnanediol glucuronide fractions were measured in aliquots of 24-hour and overnight samples of urine collected daily form seven women for one menstrual cycle. Urinary hormone excretion was correlated with daily serum estradiol (E2), progesterone (P), and luteinizing hormone (LH) level. A sharp midcyle LH peak preceded by a preovulatory rise in serum E2 and followed by luteal phase serum P levels were noted in each of the seven apparently ovulatory cycles. Twenty-four-hour and overnight urinary excretion patterns of estrogen glucuronides were similar to those of serum E2. Of the five estrogen glucuronide fractions tested, excretion of E2-17G exhibited the earliest and steepest ascending slope of the preovularoy estrogen surge and correlated best with serum E2 levels. Urinary excretion of E1-G, E2-3G, and E3-16G also showed an early and steep preovulatory rise and precede that of E3-3G, whereas urinary excretion of E3-3G exhibited the poorest correlation with serum E2 concentrations. The urinary excretion of Pd-3G rose parallel to serum P levels and was markedly elevated 2 to 3 days after the midcycle LH peak in both 24-hour and overnight collections of urine. These results indicate that among the urinary estrogen conjugate fractions tested, E2-17G is the one that most suitably predicts ovulation. The marked differences between preovulatory and postovulatory Pd-3G excretion and the fact that miligram quantities of Pd-3G are excreted each day render measurements of Pd-3G useful for the detection of ovulation and suggest that relatively simple immunochemical or enzymatic (dipstick) techniques may be developed successfully.