Estradiol in saliva for monitoring follicular stimulation in an in vitro fertilization program

Correlations between salivary- and blood-derived gonadal hormone assessments and implications for inclusion of female participants in research studies

Even in the 21st century, female participants continue to be underrepresented in human physiology research. This underrepresentation is attributable in part to the perception that the inclusion of females is more time consuming, less convenient, and more expensive relative to males because of the need to account for the menstrual cycle in cardiovascular study designs. Accounting for menstrual cycle-induced fluctuations in gonadal hormones is important, given established roles in governing vascular function and evidence that failure to consider gonadal hormone fluctuations can result in misinterpretations of biomarkers of cardiovascular disease. Thus, for cardiovascular researchers, the inclusion of females in research studies implies a necessity to predict, quantify, and/or track indexes of menstrual cycle-induced changes in hormones. It is here that methodologies are lacking. Gold standard measurement requires venous blood samples, but this technique is invasive and can become both expensive and technically preclusive when serial measurements are required. To this end, saliva-derived measures of gonadal hormones provide a means of simple, noninvasive hormone tracking. To investigate the feasibility of this technique as a means of facilitating research designs that take the menstrual cycle into account, the purpose of this review was to examine literature comparing salivary and blood concentrations of the primary gonadal hormones that fluctuate across the menstrual cycle: estradiol and progesterone. The data indicate that there appear to be valid and promising applications of salivary gonadal hormone monitoring, which may aid in the inclusion of female participants in cardiovascular research studies.

A multi-centre international study of salivary hormone oestradiol and progesterone measurements in ART monitoring

RESEARCH QUESTION

Ovarian stimulation during IVF cycles involves close monitoring of oestradiol, progesterone and ultrasound measurements of follicle growth. In contrast to blood draws, sampling saliva is less invasive. Here, a blind validation is presented of a novel saliva-based oestradiol and progesterone assay carried out in samples collected in independent IVF clinics.

DESIGN

Concurrent serum and saliva samples were collected from 324 patients at six large independent IVF laboratories. Saliva samples were frozen and run blinded. A further 18 patients had samples collected more frequently around the time of HCG trigger. Saliva samples were analysed using an immunoassay developed with Salimetrics LLC.

RESULTS

In total, 652 pairs of saliva and serum oestradiol were evaluated, with correlation coefficients ranging from 0.68 to 0.91. In the European clinics, a further 237 of saliva and serum progesterone samples were evaluated; however, the correlations were generally poorer, ranging from -0.02 to 0.22. In the patients collected more frequently, five out of 18 patients (27.8%) showed an immediate decrease in oestradiol after trigger. When progesterone samples were assessed after trigger, eight out of 18 (44.4%) showed a continued rise.

CONCLUSIONS

Salivary oestradiol hormone testing correlates well to serum-based assessment, whereas progesterone values, around the time of trigger, are not consistent from patient to patient.

Chemical analysis in saliva and the search for salivary biomarkers – a tutorial review

A review of the uses of saliva biomarkers, detection methods and requirements for new biomarkers.

Utility of salivary enzyme immunoassays for measuring estradiol and testosterone in adolescents: a pilot study

AIM

We investigated the utility of enzyme immunoassay kits for measuring low levels of salivary estradiol and testosterone in adolescents and objectively assessed prevalence of blood contamination.

METHODS

Endocrine patients provided plasma and saliva for estradiol (females) or testosterone (males) assay. Saliva samples were also tested with a blood contamination kit.

RESULTS

Picomolar levels of salivary estradiol in females failed to show any significant correlation with plasma values (r=0.20, p=0.37). The nanomolar levels of salivary testosterone in males showed a strong correlation (r=0.78, p<0.001). A significant number of saliva samples had blood contamination. After exclusion, correlations remained non-significant for estradiol, but strengthened for testosterone (r=0.88, p<0.001).

CONCLUSION

The salivary estradiol enzyme immunoassay is not clinically informative at low levels. Users should interpret clinical saliva with caution due to potential blood contamination. Our data supports the utility of the salivary testosterone enzyme immunoassay for monitoring adolescent boys on hormone developmental therapy.

Salivary Markers for Periodontal and General Diseases

The determination of biomarkers in saliva is becoming an important part of laboratory diagnostics and the prediction of not only periodontal, but also other tissue and organ diseases. Biomarkers in saliva (e.g., enzymes, protein markers, or oxidative stress markers) can be used for activity determination and for periodontal disease prognosis. Saliva also contains many markers which can predict the risk of certain diseases (e.g., diabetes mellitus, cardiovascular, oncology, endocrinology, and psychiatric diseases). The study of salivary components proteomics clearly shows the relationship of periodontal diseases and diseases of distant systems, organs, or tissues.

The Effects of Sex Hormonal Fluctuations during Menstrual Cycle on Cortical Excitability and Manual Dexterity (a Pilot Study)

AIM

To investigate whether hormonal fluctuations during the menstrual cycle affect corticospinal excitability, intracortical inhibition (ICI) or facilitation (ICF) in primary motor cortex, and also whether the hormonal fluctuations have any effect on manual dexterity in neurologically intact women.

MATERIALS AND METHODS

Twenty volunteers (10 Female, 10 Male) were included in this study. The levels of progesterone and estradiol were measured from saliva during the women's menstrual follicular, ovulation and mid-luteal phases. Motor evoked potentials were recorded from the right first dorsal interosseous muscle. Single and paired-pulse Transcranial Magnetic Stimulation (TMS) were delivered in a block of 20 stimuli. With paired-pulse technique, 3ms and 10ms inter-stimulus intervals were used to assess ICI and ICF, respectively. The Grooved Pegboard Test (GPT) was completed in each session before the TMS assessments. Male participants were tested at similar time intervals as female participants.

RESULTS

Mixed design ANOVA revealed that GPT score in female participants was significantly lower at the mid-luteal phase compared to the ovulation phase (p = 0.017). However, it was not correlated with progesterone or estrogen fluctuations during the menstrual cycle. The results also showed that the effect of phase, sex and the interaction of phase by sex for resting motor threshold, ICI or ICF were not significant (p > 0.05).

CONCLUSION

Manual dexterity performance fluctuates during the menstrual cycle in neurologically intact women, which might be due to the balance of the neuromodulatory effects of P4 and E2 in the motor cortex during different phases.

Gender differences in the validity of testosterone measured in saliva by immunoassay

We rigorously evaluated gender differences in the measurement validity of salivary testosterone. Matched serum, saliva, and finger stick blood spot specimens were collected from 40 (20 males) young adults (aged 18-27 years). Saliva was assayed for testosterone by two independent (isotopic and non-isotopic) immunoassay methods. Serum was assayed by commercially available immunoassay kits for free and total testosterone. An immunoassay was developed for the measurement of testosterone in dried blood spots and is presented in detail so as to be reproducible from this report. Regardless of assay method, salivary testosterone levels are modestly correlated with serum levels for males but not necessarily for females. Blood spot assay results were highly correlated with serum total and free testosterone for both males and females. Substitution of saliva assay results for serum values substantially underestimates known testosterone-behavior associations, and this effect is much more pronounced for females than for males. The findings have important implications for the use and potential misuse of noninvasive measures of testosterone, and with respect to statistical power, the probability of observing significant testosterone-behavior relationships.

Steroid fluctuations modify functional cerebral asymmetries: the hypothesis of progesterone-mediated interhemispheric decoupling

This study examines the modulation of functional cerebral asymmetries by gonadal hormones in three distinct groups. Young, normally cycling women performed a prototypical left (lexical decision) and two prototypical right-hemispheric tasks (figural comparison and face discrimination) during the low steroid menses and the high steroid midluteal phase. Saliva progesterone levels were measured with radioimmunoassay (RIA). Parallel to younger females, young men, and postmenopausal women were tested at matching time intervals. Results revealed significant interactions between cycle phase and visual half-field in the accuracy of all three tasks for the younger women; stronger lateralization patterns occurring during menses, while a more bilateral or at least less asymmetric cerebral organization predominated the midluteal phase, when highest levels of progesterone appear. Progesterone seemed to have a significant influence on lateralization in the figural comparison task, with high hormone levels enhancing the performance of the left hemisphere (for this task subdominant), thereby decreasing asymmetry. After menopause, when the levels of gonadal hormones are lower and more stable, the lateralization patterns for all three tasks were similar to those of men and normally cycling women during menses. These results make it likely that steroids and especially progesterone are able to reduce cerebral asymmetries. We hypothesize that progesterone attenuates the effect of glutamate on non-NMDA receptors. This could diminish cortico-cortical transmission which is mostly dependent on a glutamate-induced initial EPSP in pyramidal neurons which receive transcallosal input. The reduction in callosal transfer could then suppress the functional asymmetries.

Assessing estradiol in biobehavioral studies using saliva and blood spots: simple radioimmunoassay protocols, reliability, and comparative validity

We developed simple, reliable, and highly sensitive assay modifications of commercially available radioimmunoassay kits to measure estradiol in saliva and blood spot specimens. The saliva assay has average intra- and interassay coefficients of variation (CV) of 6.45 and 9.01%, with average analytical and serial dilution recoveries 100.65 and 89.25%. The blood spot assay has average intra- and interassay CVs of 7.57 and 8.22%, with analytical and serial dilution recoveries of 80.50 and 108.50%. The analytical sensitivity ranges of the saliva (0.25-7.50 pg/ml) and blood spot (2. 00-375 pg/ml) assays are sufficient to determine levels in the majority of pre- and postpubertal males and females. Blood spot assay results are correlated with serum estradiol levels for adult males, r (17) = 0.73, and females, r (18) = 0.96. In contrast, the serum-saliva correlation is only modest for adult females, r (14) = 0.60, and not significant for adult males. Substitution of blood spot assay results for serum values underestimates the known serum estradiol-behavior correlation by only 3.45%, whereas substitution of saliva assay results for serum values underestimates the association by 37.55%. The findings have important implications for the use and potential misuse of noninvasive measures of estradiol in studies of health and human development.

Salivary estradiol and progesterone levels in conception and nonconception cycles in women: evaluation of a new assay for salivary estradiol

OBJECTIVE

To determine the usefulness of salivary E2 and progesterone for noninvasive assessment of ovarian function.

DESIGN

Prospective study of salivary hormone levels in women planning a pregnancy.

SETTING

Department of Obstetrics and Gynecology at Northwestern University Medical School in Chicago, Illinois.

PATIENT(S)

Fourteen women aged 23-39 years with regular menstrual cycles who were planning a pregnancy.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Salivary estradiol and progesterone concentrations.

RESULT(S)

The sensitivity of the E2 assay is 2.0 pmol/L; the interassay coefficient of variation was 5.2% (mean value 17 pmol/L). Recovery of E2 added to saliva was 106%. The correlation with simultaneous serum samples was 0.71. Menstrual cycle patterns contained a preovulatory depression and a midcycle surge. By comparison with nonconception cycles, the luteal phases of conception cycles had significantly elevated salivary E2 within the first 5 days after ovulation. Salivary progesterone was significantly elevated but not until 10 days after ovulation.

CONCLUSION(S)

Salivary measurements of E2 and progesterone can be used as noninvasive methods for assessment of ovarian function. Salivary specimens can be collected at home and brought to the laboratory for analysis, obviating the need for frequent phlebotomy. The sensitivity and precision of the salivary E2 assay make it comparable with assays of serum E2 for assessing changes in hormone levels.

Composition of fluids obtained from human epididymal cysts

The fluid composition of five epididymal spermatocoeles, one epididymal cyst and a hydrocoele was examined. The fluid obtained from the spermatocoeles was a dilute suspension of mainly immotile spermatozoa. The sperm-free fluid contained less protein, phosphate, glucose, triglyceride and cholesterol than serum but more testosterone and chloride than peripheral blood. It contained no epididymal secretion products. Proteins in the fluid differed from those in serum. From the fluid composition these cysts appeared to be continuous with the rete testis, either dilatations of efferent ducts or Haller's superior aberrant duct (vas aberrans of the rete testis). Fluid from an epididymal cyst containing no spermatozoa was mainly of similar composition. In contrast, hydrocoele fluid resembles blood serum.

The prediction of ovulation and monitoring of the fertile period

Simple and reliable methods have been sought for both predicting and confirming ovulation. Application of these methods could include management of infertile couples to aid in conception and for increasing the reliability of natural family planning (NFP) as a method of birth control. With the advent of specific hormone assays, serial measurements of estrogens, progesterone (and metabolites), and luteinizing hormone have been the gold standard of monitoring ovarian function in women. However, newer and simpler methodologies have been described and are currently either in use or being tested. These include the measurement of basal body temperature (BBT), the evaluation of the volume, consistency and electro-conductivity of cervicovaginal fluid, salivary steroid content and cellular enzymatic activity, the use of enzyme-linked immunosorbent assays applied to solid-phase formats, and the investigation of new hormonal molecules as markers of reproductive state and function. These new technologies are described herein and their potential for monitoring ovarian function is discussed.

Progesterone and estradiol in saliva after in vitro fertilization and embryo transfer

The importance of the luteal function to ensure adequate implantation prompted us to assay salivary estradiol (SE2) and salivary progesterone (SP) concentration serially after embryo transfer by simple and rapid radioimmunoassays to allow a noninvasive easily repeatable approach. SE2, which has fallen 1 day after human chorionic gonadotropin injection, increased after reimplantation (day 3), plateaued during approximately 1 week, and returned to basal levels before menstruation in absence of conception or in chemical pregnancy, whereas it increased steadily in successful pregnancy. SP increased in all the cases, formed a plateau, and returned progressively to basal levels before menstruation, whereas in ongoing pregnancy there was a transitory decline in the midluteal phase followed by a rapid and continuous increase, with a significantly higher ratio day 13/day 10 in successful pregnancy.