Evaluating urinary estrogen and progesterone metabolites using dried filter paper samples and gas chromatography with tandem mass spectrometry (GC-MS/MS)

Sex, season, age and status influence urinary steroid hormone profiles in an extremely polygynous neotropical bat

Several polygynous mammals exhibit reproductive skew in which only a few males reproduce. Successful males need strength, stamina and fighting ability to exclude competitors. Consequently, during the mating season their androgens and glucocorticoids are expected to increase to support spermatogenesis and aggressive behavior. But, during the nonmating season these hormones should decline to minimize deleterious effects, such as reduced immune function. Bats that exhibit harem polygyny in which males aggressively defend large groups of females year-round are ideal for assessing hormonal and other consequences of extreme polygyny. Here we use DNA methylation to estimate age and gas chromatography, tandem mass spectrometry to profile steroid metabolites in urine of wild greater spear-nosed bats, Phyllostomus hastatus, across seasons. We find that condition, measured by relative weight, is lower during the mating season for both sexes, although it remains high in harem males during the mating season. Average age of females is greater than males, and females exhibit substantial seasonal differences in androgens, estrogens and glucocorticoids with higher levels of all hormones during the mating season. Males, however, show little seasonal differences but substantial age-associated increases in most steroid metabolites. Harem males have larger, persistently scrotal testes and are older than bachelor males. While cortisone generally declines with age, harem males maintain higher amounts of biologically active cortisol than bachelor males all year and cortisol levels increase more quickly in response to restraint in males than in females. Taken together, these results suggest that attaining reproductive dominance requires hormone levels that reduce lifespan.

Endogenous estrogen metabolites as oxidative stress mediators and endometrial cancer biomarkers

BACKGROUND

Endometrial cancer is the most common gynecologic malignancy found in developed countries. Because therapy can be curative at first, early detection and diagnosis are crucial for successful treatment. Early diagnosis allows patients to avoid radical therapies and offers conservative management options. There are currently no proven biomarkers that predict the risk of disease occurrence, enable early identification or support prognostic evaluation. Consequently, there is increasing interest in discovering sensitive and specific biomarkers for the detection of endometrial cancer using noninvasive approaches.

CONTENT

Hormonal imbalance caused by unopposed estrogen affects the expression of genes involved in cell proliferation and apoptosis, which can lead to uncontrolled cell growth and carcinogenesis. In addition, due to their ability to cause oxidative stress, estradiol metabolites have both carcinogenic and anticarcinogenic properties. Catechol estrogens are converted to reactive quinones, resulting in oxidative DNA damage that can initiate the carcinogenic process. The molecular anticancer mechanisms are still not fully understood, but it has been established that some estradiol metabolites generate reactive oxygen species and reactive nitrogen species, resulting in nitro-oxidative stress that causes cancer cell cycle arrest or cell death. Therefore, identifying biomarkers that reflect this hormonal imbalance and the presence of endometrial cancer in minimally invasive or noninvasive samples such as blood or urine could significantly improve early detection and treatment outcomes.

Dried urine spot (DUS) applied for sampling prior to the accurate HILIC-MS/MS determination of 14 amino acids

Urine amino acid analysis has proven valuable for an array of clinical or nutritional studies. However, transportation of liquid urine sample shows certain disadvantages, such as possible leakage, need for cold chain and thus higher costs for their transport. Utilization of dried urine spots (DUS) can offer an interesting alternative. In the present study, a method was developed for the determination of 14 amino acids in DUS including the testing of in-house collection device and drying of the sample before analysis. Normal filter paper was tested as the means for sample collection. Absorption and extraction experiments were performed on 3 different types of filter paper, with 3 different extraction solvents and two different solvent volumes. The solvents used were mixtures of common analytical solvents (methanol, water, acetonitrile) using total volumes of 1 mL and 1.5 mL. Finally, 1 mL of acetonitrile: methanol: water 40:40:20 (v/v/v) was chosen as the optimal system. Analysis was performed on a UHPLC-MS system, using stable isotope labeled internal standards. Method validation included the study of limits of detection (LOD) and quantification (LOQ), linearity ranges, precision, matrix effect, extraction recovery, precision, and stability for each analyte. The obtained results were satisfactory, thus enabling application of the proposed method as an alternative to the analysis of liquid urine. Further utilization of DUS can offer advantages by enabling patient centric sampling even in long distances far from the analytical laboratories.

Deep Learning Model Using Continuous Skin Temperature Data Predicts Labor Onset

Background

Changes in body temperature anticipate labor onset in numerous mammals, yet this concept has not been explored in humans.

Methods

We evaluated patterns in continuous skin temperature data in 91 pregnant women using a wearable smart ring. Additionally, we collected daily steroid hormone samples leading up to labor in a subset of 28 pregnancies and analyzed relationships among hormones and body temperature trajectory. Finally, we developed a novel autoencoder long-short-term-memory (AE-LSTM) deep learning model to provide a daily estimation of days until labor onset.

Results

Features of temperature change leading up to labor were associated with urinary hormones and labor type. Spontaneous labors exhibited greater estriol to α-pregnanediol ratio, as well as lower body temperature and more stable circadian rhythms compared to pregnancies that did not undergo spontaneous labor. Skin temperature data from 54 pregnancies that underwent spontaneous labor between 34 and 42 weeks of gestation were included in training the AE-LSTM model, and an additional 40 pregnancies that underwent artificial induction of labor or Cesarean without labor were used for further testing. The model was trained only on aggregate 5-minute skin temperature data starting at a gestational age of 240 until labor onset. During cross-validation AE-LSTM average error (true - predicted) dropped below 2 days at 8 days before labor, independent of gestational age. Labor onset windows were calculated from the AE-LSTM output using a probabilistic distribution of model error. For these windows AE-LSTM correctly predicted labor start for 79% of the spontaneous labors within a 4.6-day window at 7 days before true labor, and 7.4-day window at 10 days before true labor.

Conclusion

Continuous skin temperature reflects progression toward labor and hormonal status during pregnancy. Deep learning using continuous temperature may provide clinically valuable tools for pregnancy care.

Urinary Androgens Provide Additional Evidence Related to Metabolism and Are Correlated With Serum Androgens in Girls

Context

Androgen levels are generally measured in serum samples, but urine may be a more feasible option, especially in children, as it is a noninvasive alternative.

Objective

To assess the correlations of 10 urinary androgen metabolites with 4 serum androgens [dehydroepiandrosterone-sulfate (DHEA-S), androstenedione, and total and free testosterone] and assess if their correlations differ by participant characteristics.

Methods

Our study consisted of 44 girls, ages 6-13, who participated in the New York site of the LEGACY Girls Study and had both serum and urine samples collected at the same visit. We performed Pearson's correlation coefficient tests between 4 serum and 10 individual urinary metabolite measures and their sum. We examined the influence of participant characteristics on the magnitude and direction of the correlations.

Results

The summed urinary metabolite measures had the highest correlation with free testosterone in serum (global sum, r = 0.83) and correlated least with DHEA-S in serum (global sum, r = 0.64). The correlation between individual urinary metabolites and serum androgens ranged from 0.08 to 0.84.Two 11-oxygenated urinary metabolites (5α-androstane-3α-ol-11,17-dione5β-androstane-3α,11β-diol-17-one) were weakly correlated with all serum androgens. Participant age, weight, height, waist:hip ratio, and pubic hair growth stage changed the correlations between urinary and serum androgens measures between 10% and 213%.

Conclusion

The sum of urinary androgen metabolites was a good marker of circulating androstenedione, testosterone, and free testosterone. Individual urinary metabolites provide additional information about the metabolic processes of disease development compared to the antecedent serum androgens.

Analyzing the atypical - Methods for studying the menstrual cycle in adolescents

BACKGROUND

The female pubertal transition is characterized by a rapidly changing hormone milieu, which is heavily influenced by the first menstrual cycle - menarche. The first year following menarche is associated with menstrual cycles that are irregular and anovulatory. Peripuberty also marks the beginning of a female-biased risk for suicidality and depression, suggesting some influence by the menstrual cycle and ovarian hormone fluctuations. However, there are limited methods and guidelines for studying the menstrual cycle and related affective symptoms in this developmental window. Thus, this study's objective was to identify the most accurate methods for detecting ovulation in irregular cycles (Part 1) and develop guidelines based on these methods for determining menstrual cycle phases. These methods were applied to investigate hormones and affective symptoms based on cycle phase and ovulation status in a sample of peripubertal females (Part 2).

METHODS

Thirty-two peripubertal females (ages 11-14) provided daily urine samples of estrogen (E1G) and progesterone (PdG) metabolites and luteinizing hormone (LH), and ratings of affective symptoms for one menstrual cycle. Ten literature-derived methods for determining the presence of an LH-peak or PdG rise were compared, focusing on their feasibility for psychological research.

RESULTS

Methods by Sun et al. (2019) and Park et al. (2007) most accurately detected PdG rises and LH peaks in this sample, identifying 40.6% of cycles as ovulatory. As expected, ovulatory participants showed greater LH in the periovulatory phase (p = .001), greater PdG in the mid-luteal phase (p < .0001), and greater E1G in the periovulatory phase (p = .001) compared with anovulatory participants. Exemplary methods to compare psychological symptoms between both groups are provided.

CONCLUSIONS

Recommendations and guidelines for studying the menstrual cycle in irregular cycling adolescents are offered. Novel methods for ovulation detection identified phase-specific hormonal patterns in anovulatory and ovulatory adolescent cycles.

Comparative estrogen exposure from compounded transdermal estradiol creams and Food and Drug Administration-approved transdermal estradiol gels and patches

OBJECTIVE

The aim of this study was to evaluate the amount of estrogen exposure associated with the use of compounded transdermal estradiol (E2) creams and compare it with estrogen exposure associated with the use of Food and Drug Administration (FDA)-approved transdermal E2 patches and gels.

METHODS

This was a retrospective cohort study that used clinical laboratory data collected from January 1, 2016, to December 31, 2019. Participants were first divided into three groups: postmenopausal women on no menopausal hormone therapy (n = 8,720); postmenopausal women using either a transdermal E2 patch, gel, or cream (n = 1,062); and premenopausal women on no hormonal therapy (n = 16,308). The postmenopausal menopausal hormone therapy group was further subdivided by formulation (patch [n = 777], gel [n = 132], or cream [n = 153]) and dose range (low, mid, or high). The Jonckheere-Terpstra trend test was used to determine if there was a dose-dependent trend in urinary E2 with increasing dose of compounded E2 cream (dose categories for E2 cream subanalysis, <0.5 mg [n = 49], ≥0.5-≤1.0 mg [n = 50], ≥1.0-≤1.5 mg [n = 58], and >1.5-≤3.0 mg [n = 46]). Urinary E2 and other characteristics were compared across formulations (within each dose range) using Kruskal-Wallis one-way analysis of variance.

RESULTS

A dose-dependent, ordered trend existed for urinary E2 with increasing doses of compounded E2 cream (urinary E2 medians [ng/mg-Cr], 0.80 for <0.5 mg, 0.73 for ≥0.5-≤1.0 mg, 1.39 for ≥1.0-≤1.5 mg, and 1.74 for >1.5-≤3.0 mg; Jonckheere-Terpstra trend test, P < 0.001). Significant differences in urinary E2 concentrations were observed in all three dose ranges (Kruskal-Wallis one-way analysis of variance, P = 0.013 for low dose, P < 0.001 for mid dose, P = 0.009 for high dose). Comparison of E2 concentrations of compounded creams to E2 concentrations obtained with similar doses of FDA-approved patches and gels showed that the creams had significantly lower values than the patches and gels.

CONCLUSIONS

Estrogen exposure from compounded transdermal E2 creams increases in a dose-dependent manner; however, the amount of estrogen exposure associated with compounded creams is significantly lower than estrogen exposure associated with FDA-approved transdermal E2 patches and gels. Clinicians should be aware of the direction and magnitude of these potential differences in estrogen exposure when encountering women who have either previously used or are currently using compounded E2 creams.

Biological Fluid Microsampling for Therapeutic Drug Monitoring: A Narrative Review

Therapeutic drug monitoring (TDM) is a specialized area of laboratory medicine which involves the measurement of drug concentrations in biological fluids with the aim of optimizing efficacy and reducing side effects, possibly modifying the drug dose to keep the plasma concentration within the therapeutic range. Plasma and/or whole blood, usually obtained by venipuncture, are the "gold standard" matrices for TDM. Microsampling, commonly used for newborn screening, could also be a convenient alternative to traditional sampling techniques for pharmacokinetics (PK) studies and TDM, helping to overcome practical problems and offering less invasive options to patients. Although technical limitations have hampered the use of microsampling in these fields, innovative techniques such as 3-D dried blood spheroids, volumetric absorptive microsampling (VAMS), dried plasma spots (DPS), and various microfluidic devices (MDS) can now offer reliable alternatives to traditional samples. The application of microsampling in routine clinical pharmacology is also hampered by the need for instrumentation capable of quantifying analytes in small volumes with sufficient sensitivity. The combination of microsampling with high-sensitivity analytical techniques, such as liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), is particularly effective in ensuring high accuracy and sensitivity from very small sample volumes. This manuscript provides a critical review of the currently available microsampling devices for both whole blood and other biological fluids, such as plasma, urine, breast milk, and saliva. The purpose is to provide useful information in the scientific community to laboratory personnel, clinicians, and researchers interested in implementing the use of microsampling in their routine clinical practice.

A randomized, double-blind, placebo-controlled, cross-over trial to evaluate the effect of EstroSense® on 2-hydroxyestrone:16α-hydroxyestrone ratio in premenopausal women

OBJECTIVES

Some estrogen metabolites are associated with increased breast cancer risk, while others are protective. Research efforts have focused on modifiable factors, including bioactive compounds found in food or supplements, promoting estrogen profiles with anti-cancer properties. EstroSense^® is a nutraceutical product with bioactive compounds, including Indole-3-carbinol and green-tea catechins, which may favourably affect estrogen profiles. This study was conducted to determine if EstroSense use, compared to placebo, promotes a higher urinary 2-hydroxyestrone:16α-hydroxyestrone ratio (2-OHE₁:16α-OHE₁), a biomarker associated with a lowered risk of breast cancer.

METHODS

A total of 148 premenopausal women were recruited from British Columbia, Canada to participate in a randomized, double-blind, cross-over, multicentre, placebo-controlled study in which women were randomized to a treatment sequence that consisted of either EstroSense^®, followed by placebo or vice-versa. The women were instructed to consume three capsules per day of EstroSense^® or the placebo for three menstrual cycles (∼12 weeks). The primary outcome was the measurement of 2-OHE1:16α-OHE1 in casual samples at baseline and after each treatment phase.

RESULTS

After 12 weeks of intervention, the mean (95% CI) urinary 2-OHE₁:16α-OHE₁ was 4.55 (2.69, 6.42) (p<0.001) higher following EstroSense than placebo adjusted for baseline values.

CONCLUSIONS

EstroSense use led to markedly higher urinary 2-OHE1:16α-OHE1 than the placebo, a biomarker associated with a lower risk of breast cancer.

REGISTRATION

http://clinicaltrials.gov (NCT02385916).

New approaches for developing biomarkers of hormonal contraceptive use

To identify biomarkers of hormonal contraceptive (HC) use in urine and saliva, we conducted a pilot study with 30 women initiating levonorgestrel (LNG) containing combined oral contraceptives (COCs) or depot medroxyprogesterone acetate (DMPA) (15/group). Based on established COC pharmacokinetics, we collected serum and urine samples before COC ingestion and during Days one and three of use, or before DMPA injection and on Days 21 and 60 post-injection. We used liquid chromatography-tandem mass spectrometry (LC-MS/MS) to measure serum/urine LNG and MPA. LNG was undetectable at baseline (specificity 100%); post ingestion, most urine samples had detectable LNG levels (sensitivity: 80% 6 h post Dose one, 93% 6 h post Dose three). We used a DetectX LNG immunoassay kit and showed 100% sensitivity measuring urine LNG. Urine MPA levels were undetectable in 14/15 women at baseline (specificity 91%); post-injection all urine samples had detectable MPA levels (sensitivity: 100% days 21 and 60). Results suggest urine sampling can be used to identify a biomarker of LNG and MPA use. Based on evidence from other steroidal hormonal studies showing changes affecting the transcriptome profile of saliva at 24 h, we used the same (COC, DMPA) timepoints to collect saliva. We performed transcriptome analysis and detected several differentially expressed genes in DMPA users' saliva on Days 21 and 60 compared to baseline; none among COC users. We plan further research of differential gene expression in saliva as a HC biomarker of DMPA use, and will explore longer periods of COC use and saliva collection times, and application of microRNA sequencing to support using saliva as a COC biomarker.

Assessment of estrogen exposure from transdermal estradiol gel therapy with a dried urine assay

Transdermal estradiol gel is a commonly used menopausal hormone therapy. In research studies investigating the pharmacokinetics and clinical utility of transdermal estradiol gels, serum is often used to measure estradiol levels. Serum results only represent a moment in time during phlebotomy and thus provide little information and allow for limited inference unless serial measurements are performed. In contrast, dried urine may provide a representation of serum estradiol levels over a longer period of time, while also being non-invasive and easier to collect. The primary aim of this study was to evaluate a dried urine method to determine if it may be a viable option for evaluating estrogen exposure resulting from transdermal estradiol gel use. A secondary aim was to explore differences in the urinary estrogen profiles of premenopausal women on no therapy and postmenopausal women who were either on transdermal estradiol gel therapy or no therapy at all. The results of this study demonstrated that the expected dose-proportional changes in estrogen exposure can be observed in the urinary estrogen profile using a GC-MS/MS dried urine assay. The GC-MS/MS assay also showed the differences in the urinary estrogen profiles of premenopausal women, postmenopausal women on estrogen replacement therapy, and postmenopausal women on no therapy.

Self-Monitoring of Urinary Hormones in Combination with Telemedicine - a Timely Review and Opinion Piece in Medically Assisted Reproduction

Cycle monitoring via ultrasound and serum-based hormonal assays during medically assisted reproduction (MAR) can provide information on ovarian response and assist in optimizing treatment strategies in addition to reducing complications such as ovarian hyperstimulation syndrome (OHSS). Two surveys conducted in 2019 and 2020, including overall 24 fertility specialists from Europe, Asia and Latin America, confirmed that the majority of fertility practitioners routinely conduct hormone monitoring during MAR. However, blood tests may cause inconvenience to patients. The reported drawbacks of blood tests identified by the survey included the validity of results from different service providers, long waiting times and discomfort to patients due to travelling to clinics for tests and repeated venepunctures. Historically, urine-based assays were used by fertility specialists in clinics but were subsequently replaced by more practical and automated serum-based assays. A remote urine-based hormonal assay could be an alternative to current serum-based testing at clinics, reducing the inconvenience of blood tests and the frequency of appointments, waiting times and patient burden. Here we provide an overview of the current standard of care for cycle monitoring and review the literature to assess the correlation between urine-based hormonal assays and serum-based hormonal assays during MAR. In addition, in this review, we discuss the evidence supporting the introduction of remote urine-based hormonal monitoring as part of a novel digital health solution that includes remote ultrasound and tele-counselling to link clinics and patients at home.

Serial Hydrolysis for the Simultaneous Analysis of Catecholamines and Steroids in the Urine of Patients with Alopecia Areata

Catecholamines and steroids are well-known neurotransmitters and hormones that rapidly change the excitability of neurons. Alopecia areata is a disease for which the exact cause is unknown, but it is considered to be associated with stress, and so the simultaneous analysis of catecholamines and steroids is required for the diagnosis of alopecia areata. Thus, we herein report the simultaneous analysis of catecholamines and steroids bearing different functional groups for the first time, during which it was necessary to carry out a serial hydrolysis procedure. Following hydrolysis of the urine samples to produce the free forms from the urinary conjugates, ethyl acetate extractions were carried out, and chemical derivatization was performed using dansyl chloride to increase the sensitivity of the liquid chromatography-tandem mass spectrometry method. The matrix effects and recoveries of this analytical method were validated, giving values of 85.4-122.9% and 88.8-123.0%, respectively. In addition, the method accuracy and precision were assessed, giving values of 0.4-21.5% and 2.0-21.6% for the intra-day and inter-day precisions, respectively. This validated method was then applied to identify differences between patients with and without alopecia areata, wherein the metanephrine content was found to be significantly higher in the alopecia areata patient group. This quantitative profiling method can also be applied to steroid-dependent diseases, as well as catecholamine-related diseases.

Reliability of a dried urine test for comprehensive assessment of urine hormones and metabolites

Background

Mass spectrometry allows for analysis of multiple hormone and organic acid metabolites from small urine volumes; however, to assess the full extent of daily hormone production, 24-h urine collections are usually required. The aims of this study were, first, to confirm that mass spectrometric analysis of an array of hormones and organic acids would yield similar results in both liquid and dried urine, and, second, to determine if collection of four dried spot urine samples could be substituted for a 24-h collection when measuring reproductive hormones.

Methods

Two study populations were included in this prospective observational study. Twenty individuals collected both a spot liquid urine and dried urine on filter paper to analyze eight organic acids. A second group of 26 individuals collected both a 24-h urine and four dried spot urines during waking hours throughout the same day for evaluation of 17 reproductive hormones and metabolites; data from 18 of these individuals were available to compare liquid versus dried urine results. Dried urine was extracted, hydrolyzed, and derivatized before analysis by mass spectrometry; all analytes from dried urine were normalized to urine creatinine.

Results

Reproductive hormone results from dried and liquid urine were in excellent agreement with intraclass correlation coefficients (ICCs) greater than 0.90; comparison of dried to liquid urine for organic acids showed good to excellent agreement (ICC range: 0.75 to 0.99). Comparison between the 4-spot urine collection and 24-h urine collection methods showed excellent agreement (ICC > 0.9) for 14 of the 17 urine metabolites and good agreement for the others (ICC 0.78 to 0.85) with no systematic differences between the two methods of collection.

Conclusions

The burden of urine collection can be reduced using collection of four spot dried urines on filter paper without compromising comparability with hormone results from a 24-h urine collection. A large number of urine analytes can be assessed from the dried urine with similar results to those from liquid urine. Given the ease of sample handling, this 4-spot dried urine assay would be useful for both clinical assessment of patients and for large epidemiologic studies.

Supplementary information

The online version contains supplementary material available at 10.1186/s13065-021-00744-3.

Falsely elevated serum estradiol due to heterophile antibody interference: a case report

Falsely elevated estradiol is rare, may result from heterophile antibody interference, and can result in unnecessary investigation and intervention. We present the case of a 56-year-old female with falsely elevated estradiol levels inconsistent with her overall clinical picture, which ultimately led to an unnecessary surgical procedure. With the use of alternative analytical platforms and a heterophile antibody blocking agent, we determined the false elevation was due to heterophile antibody interference. Clinicians must suspect and investigate for laboratory error when the clinical picture contradicts laboratory results.

Quantification of progesterone in beef with marbling using liquid chromatography-tandem mass spectrometry with stable isotope-labelled standards

Progesterone (P4) is contained naturally in animal tissue, and it is also used as a veterinary drug in cattle for treatment purposes. To assess the risk from P4 residues in beef derived from treated cattle, it is essential to quantify the P4 contained naturally in cattle tissue (endogenous P4). Therefore, we performed a method validation for the quantification of endogenous P4 (method quantification limit = 0.06 ng g^-1) by using isotope-labelled P4s, and investigated the P4 contents in Japanese beef (n= 112; 0.07 to 121 ng g^-1). The P4 contents in cattle muscle ranged from 0.07 to 54.3 ng g^-1 in males, and from 0.27 to 121 ng g^-1 in females. Our investigation also indicated that the developed method using both ¹³C- and deuterium-labelled P4 standards could be used to certify the recovery of P4 from cattle muscle containing various amounts of intramuscular fat, and enabled the determination of the P4 content in all Japanese beef samples that exceeded the method quantification limit.

A review of recent advances in microsampling techniques of biological fluids for therapeutic drug monitoring

Conventional sampling of biological fluids often involves a bulk quantity of samples that are tedious to collect, deliver and process. Miniaturized sampling approaches have emerged as promising tools for sample collection due to numerous advantages such as minute sample size, patient friendliness and ease of shipment. This article reviews the applications and advances of microsampling techniques in therapeutic drug monitoring (TDM), covering the period January 2015 - August 2020. As whole blood is the gold standard sampling matrix for TDM, this article comprehensively highlights the most historical microsampling technique, the dried blood spot (DBS), and its development. Advanced developments of DBS, ranging from various automation DBS, paper spray mass spectrometry (PS-MS), 3D dried blood spheroids and volumetric absorptive paper disc (VAPD) and mini-disc (VAPDmini) are discussed. The volumetric absorptive microsampling (VAMS) approach, which overcomes the hematocrit effect associated with the DBS sample, has been employed in recent TDM. The sample collection and sample preparation details in DBS and VAMS are outlined and summarized. This review also delineates the involvement of other biological fluids (plasma, urine, breast milk and saliva) and their miniaturized dried matrix forms in TDM. Specific features and challenges of each microsampling technique are identified and comparison studies are reviewed.

Ultradian rhythms in heart rate variability and distal body temperature anticipate onset of the luteinizing hormone surge

The menstrual cycle is characterized by predictable patterns of physiological change across timescales. Although patterns of reproductive hormones across the menstrual cycle, particularly ultradian rhythms, are well described, monitoring these measures repeatedly to predict the preovulatory luteinizing hormone (LH) surge is not practical. In the present study, we explored whether non-invasive measures coupled to the reproductive system: high frequency distal body temperature (DBT), sleeping heart rate (HR), sleeping heart rate variability (HRV), and sleep timing, could be used to anticipate the preovulatory LH surge in women. To test this possibility, we used signal processing to examine these measures in 45 premenopausal and 10 perimenopausal cycles alongside dates of supra-surge threshold LH and menstruation. Additionally, urinary estradiol and progesterone metabolites were measured daily surrounding the LH surge in 20 cycles. Wavelet analysis revealed a consistent pattern of DBT and HRV ultradian rhythm (2-5 h) power that uniquely enabled anticipation of the LH surge at least 2 days prior to its onset in 100% of individuals. Together, the present findings reveal fluctuations in distal body temperature and heart rate variability that consistently anticipate the LH surge, suggesting that automated ultradian rhythm monitoring may provide a novel and convenient method for non-invasive fertility assessment.

Reproductive hormone measurement from minimally invasive sample types: Methodological considerations and anthropological importance

Energetic investment in human reproduction has long been recognized as costly, influencing developmental, physiological, and behavioral patterns in males and females. These effects are largely coordinated through the actions of reproductive hormones (eg, testosterone, estradiol, and progesterone). Here, the utility and limitations of minimally invasive sampling techniques are explored, providing a novel perspective on how reproductive hormone measurements can enhance reproductive endocrinology research. Salivary steroid measures are most commonly used, although several dried blood spot and urine assays are also available, and researchers continue to explore the efficacy of other sample types. These relatively simple measures have facilitated the collection of multiple samples from a single participant, allowing researchers to more accurately track the diurnal and cyclical variation exhibited by many reproductive hormones. Ultimately, the ability to collect fine-grained participant data allows biological anthropologists to better test questions central to human reproductive ecology, life history theory, and public health. For example, fieldwork using these techniques suggests that testosterone profile variation across populations is influenced by energetic constraints and reproductive status. Moreover, hormone concentrations shape the development of sex characteristics, with implications for evolutionary questions related to sexual selection. Hormone levels also can be used to identify a range of medical concerns (eg, suppressed hormone production levels linked with psychosocial stress). These findings highlight how minimally invasive collection techniques can be applied to test diverse evolutionary hypotheses and identify important health concerns. Still, more work is needed to standardize collection and laboratory analysis procedures, thereby enabling more direct data comparisons between researchers.

Field methods and strategies for assessing female reproductive functioning

A detailed understanding of female reproductive functioning is important to many disciplines including anthropology, evolutionary theory, demography, psychology, and biomedicine. In this article, I describe strategies and methods that have been used successfully in community-based studies of human reproduction, many in remote locales, to produce high quality biomarker data. These techniques are applicable to a wide range of research questions and populations, and to persons from adolescence through senescence. I give particular attention to the inherent challenges imposed by the cyclical and somewhat unpredictable nature of the hypothalamic-pituitary-ovarian axis including the necessity and difficulty of ascertaining the timing and occurrence of ovulation, the limits of different sampling regimes for capturing fluctuations in reproductive hormones, and the critical importance of recognizing and, when possible, reducing selection bias. I discuss the relative advantages and disadvantages of collecting saliva, urine, and dried blood spots, and describe some of the subtleties involved in collecting contamination-free samples. Once samples are collected, they must be stored in a manner that minimizes degradation; I describe techniques to keep samples cold even without access to electricity or dry ice. I also discuss various issues that should be considered during initial discussions with a laboratory and when samples are assayed by the laboratory. I include examples of techniques that have worked well in actual field studies, and examples of flawed analytical approaches that should be avoided. With these and other tools, even under technology-sparse conditions, researchers can investigate variability in human physiology across the breadth of human habitats.

A review of strategies for untargeted urinary metabolomic analysis using gas chromatography-mass spectrometry

BACKGROUND

Human urine gives evidence of the metabolism in the body and contains different metabolites at various concentrations. A number of analytical techniques including mass spectrometry (MS) and nuclear magnetic resonance (NMR) have been used to obtain metabolites levels in urine samples. However, gas chromatography-mass spectrometry (GC-MS) is one of the most widely used techniques for urinary metabolomics studies due to its higher sensitivity, resolution, reproducibility, reliability, relatively low cost and ease of operation compared to liquid chromatography-mass spectrometry and NMR.

AIM OF REVIEW

This review looks at various aspects of urine preparation prior to analysis by GC-MS including sample storage, urease pretreatment, derivatization, use of internal standard and quality control samples for data correction. In addition, most common types of inlet liners, ionization techniques and columns are discussed and a summary of mass analyzers are also highlighted. Lastly, the role of retention index in metabolite identification and data normalization methods are presented.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The purpose of this review is summarizing methods of sample storage, pretreatment, and GC-MS analysis that are mostly used in urine metabolomics studies. Specific emphasis is given to the critical steps within the GC-MS urine metabolomics that those new to this field need to be aware of and the remaining challenges that require further attention and studies.

Advancements in the gold standard: Measuring steroid sex hormones by mass spectrometry

Sex hormones, such as testosterone and estrogens, play an essential role in regulating physiological and reproductive development throughout the lifetime of the individual. Although variation in levels of these hormones are observed throughout the distinct stages in life, significant deviations from reference ranges can result in detrimental effects to the individual. Alterations, by either an increase or decrease, in hormone levels are associated with physiological changes, decreased reproductive capabilities, and increased risk for diseases. Hormone therapies (HTs) and assisted reproductive technologies (ARTs) are commonly used to address these factors. In addition to these treatments, gender-affirming therapies, an iteration of HTs, are also a prominent treatment for transgender individuals. Considering that the effectiveness of these treatments relies on achieving therapeutic hormone levels, monitoring of hormones has served as a way of assessing therapeutic efficay. The need for reliable methods to achieve this task has led to great advancements in methods for evaluating hormone concentrations in biological matrices. Although immunoassays are the more widely used method, mass spectrometry (MS)-based methods have proven to be more sensitive, specific, and reliable. Advances in MS technology and its applications for therapeutic hormone monitoring have been significant, hence integration of these methods in the clinical setting is desired. Here, we provide a general overview of HT and ART, and the immunoassay and MS-based methods currently utilized for monitoring sex hormones. Additionally, we highlight recent advances in MS-based methods and discuss future applications and considerations for MS-based hormone assays.

Development and validation of LC-ESI-MS/MS methods for quantification of 27 free and conjugated estrogen-related metabolites

An imbalance in the estrogen metabolism has been associated with an increased risk of breast cancer development. Evaluation of the estrogen biotransformation capacity requires monitoring of various estrogen metabolites. Up to now, only some estrogen metabolites could be measured in urine. However, in order to offer tailor made nutritional support or therapies, a complete estrogen metabolite profile is required in order to identify specific deficiencies in this pathway for each patient individually. Here, we focused on this need to quantify as many as possible of the estrogen-related metabolites excreted in urine. The method was developed to quantify 27 estrogen-related metabolites in small urine quantities. This entailed sample clean-up with a multi-step solid phase extraction procedure, derivatisation of the metabolites in the less water-soluble fraction through dansylation, and analyses using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The metabolites accurately quantified by the method devised included parent estrogens, hydroxylated and methylated forms, metabolites of the 16α-hydroxyestrogen pathway, sulphate and glucuronide conjugated forms, precursors and a related steroid hormone. This method was validated and enabled quantification in the high picograms and low nanograms per millilitre range. Finally, analyses of urine samples confirmed detection and quantification of each of the metabolites.

Establishment of an immunofiltration strip for the detection of 17β-estradiol based on the photothermal effect of black phosphorescence

In this study, a novel immunofiltration strip method with temperature as the readout signal based on the photothermal effect of black phosphorus nanosheets was established. The temperature was monitored by a portable temperature sensor.