The Use of Estrone-3-Glucuronide and Pregnanediol-3-Glucuronide Excretion Rates to Navigate the Continuum of Ovarian Activity.

The patterns of a woman's normal ovarian activity can take many forms from childhood to menopause. These patterns lie on a continuum ranging from no ovarian activity to a fully fertile ovulatory cycle, but among the other defined patterns are cycles with anovulatory ovarian activity, including luteinized unruptured follicles (LUFs), and ovulatory cycles with deficient or short luteal phases. For any woman, these patterns can occur in any order, and one can merge into the next, without an intervening bleed, or be missed entirely. Consequently, it is not yet possible to predict the pattern of a future cycle, but it is possible to use our knowledge of the continuum to interpret the current cycle, which has clear implications for the management of personal fertility. An individual's position in the continuum can be monitored directly in real time by daily monitoring of ovarian hormone excretion rates, without either calendar-type calculations or reference to population means and standard deviations. The excretion of urinary estrone glucuronide (E1G) gives a direct measure of follicular growth, and the post-ovulatory rise in urinary pregnanediol glucuronide (PdG) following an E1G peak provides good evidence of ovulation. Specific values of the PdG excretion rate can be used to determine whether a cycle is anovulatory with or without a LUF, or is ovulatory and infertile or ovulatory and fertile. These specific values are important signposts for navigating the continuum. For a woman to take advantage of the knowledge of the continuum, the data must be reliable, and their interpretation has to be based on the underlying science and provided in an appropriate form. We discuss the various factors involved in acquiring and providing such information to enable each woman to navigate her own reproductive life.

Establishment of a reference ELISA for measurement of universal thresholds of pregnanediol glucuronide excretion rates using urine samples diluted to a constant volume per unit time.

An enzyme-linked immunosorbent assay (ELISA) for measurement of pregnanediol-3α-glucuronide (PdG) excretion rates in urine samples diluted to 150 mL/h before analysis is described. The sensitivity of the 9 optimized standard curves was 0.093 ± 0.070 µmol PdG/24 hr, with the multiple combined standard curves having a mean mid-point (EC50) of 6.88 µmol PdG/24 hr. The PdG threshold excretion rate of 7.0 µmol/24 hr, which is used as a marker for the end of fertility, was situated in the most accurate region of the standard curve. The specificity of the ELISA was determined using normal variate transformation to compare seven menstrual cycle profiles obtained with the ELISA method with the profiles obtained previously using a validated radioimmunoassay (RIA) method. The cycle profiles all agreed within experimental error, and a high degree of correlation using Deming regression was obtained. The correlation equation was Y = 1.57X-0.11 µmol PdG/24 hr (n = 200; r = 0.932). The PdG excretion rates determined by the ELISA were 50% higher than given by RIA, but the normal ranges were similar to those given by the original reference gas liquid chromatographic method. The ELISA assay was therefore suitable as a reference method for measurement of thresholds of PdG excretion rates.

Monitoring of ovarian activity by measurement of urinary excretion rates using the Ovarian Monitor, Part IV: the relationship of the pregnanediol glucuronide threshold to basal body temperature and cervical mucus as markers for the beginning of the post-ovulatory infertile period.

STUDY QUESTION: Do the basal body temperature (BBT) shift and the cervical mucus markers for the beginning of the post-ovulatory infertile phase (POIP) of a menstrual cycle agree with the corresponding urinary pregnanediol glucuronide (PdG) threshold value? SUMMARY ANSWER: Perfect agreement between the cervical mucus markers and BBT shift and the hormonal definition of the start of post-ovulatory infertility occurred for only 7-17% of the cycles. WHAT IS KNOWN ALREADY: The PdG threshold of 7.0 µmol/24 h is an objective and accurate marker for the beginning of the POIP. The rise in serum progesterone also produces the BBT shift and changes in cervical mucus which determine the mucus peak. Serum progesterone and urinary PdG are closely correlated when variations in urine volume are taken into account. STUDY DESIGN, SIZE, DURATION: Individual menstrual cycle profiles of urinary PdG excretion rates for 91 fertile cycles from normally cycling women were analysed to identify the day of the beginning of the POIP. These days were compared with those determined by the day of the BBT shift +2 days, the day of the mucus peak +4 days and the later of these two indicators. The study lasted 3 years. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 62 women with normal menstrual cycles were recruited from three centres: Palmerston North, New Zealand; Sydney, Australia and Santiago, Chile. The cycles were displayed individually in a proprietary database program which recorded the PdG excretion rates, the BBT shift day and the cervical mucus peak day. A group of 15 women from a separate Chilean study had PdG urinary data measured as well as their day of ovulation determined by ultrasound. MAIN RESULTS AND THE ROLE OF CHANCE: The BBT and cervical mucus markers differed significantly in their identification of the beginning of the POIP when compared with the PdG excretion rate of 7.0 µmol/24 h. The observation that the BBT shift day and the mucus peak day could be identified even though the PdG excretion rates were still at baseline levels in some cycles could lead to an unexpected pregnancy for women using these natural family planning (NFP) indicators. LIMITATIONS, REASONS FOR CAUTION: The study consisted only of fertile cycles from women with regular cycles of 20-40 days duration. All the women were intending to avoid a pregnancy during the study, thus the limits of the fertile window were not tested. WIDER IMPLICATIONS OF THE FINDINGS: The NFP signals occurring earlier than the PdG threshold day could lead to an unexpected pregnancy. The signals occurring on the same day or later than the PdG threshold would not lead to unexpected pregnancies, but would require extra abstinence that could lead to non-compliance with the NFP method. A possible improvement in reliability of NFP methods is suggested. STUDY FUNDING/COMPETING INTERESTS: This study (project #90905) was funded by the NDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP). D.G.C. currently works for a diagnostic development company, Science Haven Ltd. The other authors have nothing to declare.

Estimation of the uncertainty of analyte concentration from the measurement uncertainty.

Ligand-binding assays, such as immunoassays, are usually analysed using standard curves based on the four-parameter and five-parameter logistic models. An estimate of the uncertainty of an analyte concentration obtained from such curves is needed for confidence intervals or precision profiles. Using a numerical simulation approach, it is shown that the uncertainty of the analyte concentration estimate becomes significant at the extremes of the concentration range and that this is affected significantly by the steepness of the standard curve. We also provide expressions for the coefficient of variation of the analyte concentration estimate from which confidence intervals and the precision profile can be obtained. Using three examples, we show that the expressions perform well.

Conjugation of estrone glucuronide with human lysozyme.

Human milk lysozyme was conjugated with estrone glucuronide to give a monoacylated conjugate, two disubstituted isoforms, and one trisubstituted isoform in 99.4% yield. The conjugates were pure and highly inhibited (>98%) by the anti-estrone glucuronide antibody. The clearing curves were biphasic for all four conjugates but a 3 min initial rate assay was established and used to measure a normal menstrual cycle profile of estrone glucuronide excretion rates. The marked differences between the hen egg white and human milk lysozyme conjugates show that near identical tertiary structures do not necessarily imply similar physical, chemical, biochemical, and kinetic behavior.

Monitoring of ovarian activity by daily measurement of urinary excretion rates of oestrone glucuronide and pregnanediol glucuronide using the Ovarian Monitor, Part III: variability of normal menstrual cycle profiles.

STUDY QUESTION: What are the characteristics of, and how variable are, individual normal menstrual cycle profiles of excretion rates for the urinary metabolites oestrone glucuronide (E1G) and pregnanediol glucuronide (PdG)? SUMMARY ANSWER: There is a continuum of menstrual cycle profiles that differ from standard textbook profiles but which can be understood simply in terms of growth, atresia and ovulation of ovarian follicles. WHAT IS KNOWN ALREADY: Point-of-care assays with the Ovarian Monitor pre-coated assay tubes, using urine samples diluted to a constant volume per unit time, give laboratory accurate clinical data for individual menstrual cycles. Lay operators can perform the point-of-care assay system at home to achieve reliable and reproducible results, which can be used for natural family planning. STUDY DESIGN, SIZE, DURATION: This prospective study involved 62 women, with normal menstrual cycles, recruited from three centres: Palmerston North, New Zealand, Sydney, Australia and Santiago, Chile. The study lasted 3 years. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women collected daily urine samples and determined their E1G and PdG rates with a pre-coated enzyme assay system known as the Ovarian Monitor. For two cycles, the assays were repeated in a study centre and the results were averaged to give 113 individual menstrual cycles for analysis. The cycles were displayed individually in a proprietary database program. MAIN RESULTS AND THE ROLE OF CHANCE: The individual normal hormonal profiles were more complex than the classic composite curves for 40% of the cycles. Of 113 ostensibly normal cycles, only 91 were potentially fertile and 22 had some luteal phase defect. The oestrone glucuronide and PdG excretion rates were reliable and informative in the non-invasive elucidation of ovulation and ovarian function for both simple and complex profiles. Daily monitoring revealed the variability of normal menstrual cycle profiles. The LH peaks were variable and ambiguous markers for ovulation. LIMITATIONS, REASONS FOR CAUTION: The study consisted of cycles only from women with regular cycles of 20-40 days duration. All the women were intending to avoid a pregnancy during the study thus the limits of the fertile window were not tested. WIDER IMPLICATIONS OF THE FINDINGS: The principles established in this study should apply to cycles of any length. All peaks in oestrone glucuronide excretion should be tested by concurrent measurements of PdG, which gives a positive indication of the fate of the follicle it represents. The Ovarian Monitor provides a useful addition for practitioners of natural family planning. STUDY FUNDING/COMPETING INTEREST(S): Financial support for this study was obtained from the UNDP/UNFPA/World Bank/WHO Special Programme of Research, Development and Research Training in Human Reproduction (HRP). D.G.C. is currently employed by and holds stock in Manawatu Diagnostics Ltd, a company in the development phase of a potentially competing product. The remaining authors have nothing to declare.

Monitoring of ovarian activity by measurement of urinary excretion rates of estrone glucuronide and pregnanediol glucuronide using the Ovarian Monitor, Part II: reliability of home testing.

BACKGROUND: The UNDP/WHO/World Bank/Special Programme of Research, Development and Research Training in Human Reproduction (Geneva) set up a study to determine whether it is feasible for women to monitor their ovarian activity reliably by home testing. Daily self-monitoring of urinary hormone metabolites for menstrual cycle assessment was evaluated by comparison of results obtained with the Home Ovarian Monitor by untrained users both at home and in study centres. METHODS: Women collected daily data for urinary estrone glucuronide (E1G) and pregnanediol glucuronide (PdG) for two cycles, then the procedure was repeated in the women's local centre (in Chile, Australia or New Zealand) giving a total of 113 duplicate cycles. The tests were performed without the benefit of replicates or quality controls. The home and centre cycles were normalized and compared to identify assay errors, and the resulting home and centre menstrual cycle profiles were averaged. RESULTS: Reliable mean cycle profiles were obtained with the home and centre excretion rates agreeing to within 36 ± 21 nmol/24 h for E1G and 0.77 ± 0.28 µmol/24 h for baseline PdG values (1-5 µmol/24 h). The cycles had a mean length of 28.1 ± 3.1 days (n = 112; 5th and 95th percentiles: 24 and 35 days, respectively), a mean follicular phase of 14.8 ± 3.1 days (n = 107; 5th and 95th percentiles: 11 and 21 days) and a mean luteal phase length of 13.3 ± 1.5 days (n = 106; 5th and 95th percentiles: 11 and 17 days), calculated from the day of the LH peak. CONCLUSIONS: The study confirmed that the Ovarian Monitor pre-coated assay tubes worked well even in the hands of lay users, without standard curves, quality controls or replicates. Point-of-care monitoring to give reliable fertility data is feasible.

Validation of a reference ELISA for estrone glucuronide using urine samples normalized by dilution to a constant rate of urine production.

A direct enzyme linked immunosorbent assay (ELISA) system has been optimized as a reference method for the measurement of first statistically significant rises in estrone glucuronide excretion rates in human urine by analysing samples pre-diluted at the time of the collection by the women subjects to a constant urine production rate of 150 mL/h. Validation was achieved by correlation of the individual menstrual cycle profiles with the corresponding estrone glucuronide excretion rates determined by radioimmunoassay (RIA) on the same urine samples for a total of 221 samples from nine cycles. The pre-dilution procedure removed random variations due to fluctuations in the daily rate of urine excretion and minimized between sample matrix effects. When the ELISA data were correlated with the RIA data, Deming regression gave a slope of 1.20+/-0.03 and an intercept of 4.6+/-1.8 nmol/24h (r=0.944) and a random experimental error of 14.2 nmol/24h. The major difference in the measurements was a proportional error of 20%, which was present in either the ELISA or RIA methods or in both. Comparison of the standard normal variate transformation of the ELISA and RIA data gave hormonal profiles of the individual menstrual cycles (N=9) that overlapped almost perfectly. Statistically significant rises or falls in the magnitude of the excretion rate in one profile were mirrored faithfully in the other.

Clearing of suspensions of Micrococcus lysodeikticus catalysed by lysozymes from hen, goose, and turkey egg whites, human milk, and phage T4. Assessment of potential as signal generators for homogeneous enzyme immunoassays for urinary steroids.

Lysozymes (3.2.1.17) from goose (Anser anser) egg white, turkey (Melagris gallopavo) egg white, phage T4 and human milk were compared with hen egg white lysozyme in their ability to clear a suspension of Micrococcus lysodeikticus. All of the lysozymes, except hen egg white lysozyme, catalysed the clearing of the Micrococcus lysodeikticus suspension in a biphasic fashion. Compared to hen egg white lysozyme, the total absorbance or transmission change over 5 and 20 minutes was less in all cases, except for human lysozyme. Human lysozyme was, therefore, a potential alternative, more rapid signal generator for the measurement of urinary estrone glucuronide excretion rates because of its structural similarity to hen egg white lysozyme. The apparent K(M) values for hen egg white lysozyme increased with the enzyme concentration.

Use of defined estrone glucuronide-hen egg white lysozyme conjugates as signal generators in homogeneous enzyme immunoassays for urinary estrone glucuronide.

Three structurally characterized estrone glucuronide-lysozyme conjugates, E1 (a 60:40 mixture acylated at K3 and K97), E3 (acylated at K33), and E5 (acylated at both K33 and K97) were isolated and purified using a combination of cation-exchange chromatography on S-sepaharose in 7M urea and hydrophobic interaction chromatography on butyl sepharose. Urea was essential to separate the conjugates into six chromatographically homogeneous fractions. In the absence of urea, complex mixtures of lysozyme and the six conjugate fractions were always encountered. The E1, E3, and E5 conjugates were highly inhibited by a sheep polyclonal anti-estrone glucuronide antibody only after the hydrophobic interaction chromatography step. The high level of inhibition enabled all three conjugates to be utilized as signal generators in homogenous enzyme immunoassays for urinary estrone glucuronide. Despite the apparently higher affinity of E3 for the antibody, both E1 and E3 gave standard curves that were indistinguishable provided that 1.7-fold more antiserum was used for E1. Both E1 and E3 yielded menstrual cycle urinary data that agreed with that provided by the Ovarian Monitor pre-coated assay tubes. Although, the menstrual cycle pattern was similar for the three signal generators, the E1G excretion rates yielded by E5 as the signal generator were only 60% of the reference values. Despite structural differences, there was no advantage gained in separating E1 and E3, but higher substituted conjugates such as E5 need removal for best assay performance.