Characterizing the steroidal milieu in amniotic fluid of mid-gestation: A LC-MS/MS study

Steroid profiling in the amniotic fluid: reference range for 12 steroids and interest in 21-hydroxylase deficiency

INTRODUCTION

Determination of steroid levels in the amniotic fluid gives some insight on foetal adrenal and gonadal functions. Our objectives were to establish reference ranges of 12 steroid levels throughout pregnancy and to compare them with steroid levels from pregnancies with foetuses presenting 21-hydroxylase deficiency (21OHD).

MATERIALS AND METHODS

Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was applied to 145 "control" amniotic fluid samples from gynaecology activity (12 + 6 to 32 + 4 Gestational Weeks, GW). The following steroids were analysed according to gestational age and compared to 23 amniotic fluid samples from foetuses with classic 21-hydroxylase deficiency confirmed by molecular studies: delta-4-androstenedione (D4), dehydroepiandrosterone (DHEA), 17-hydroxyprogesterone (17OHP), 11-deoxycortisol (11OH), 21-deoxycortisol (21OH), corticosterone, deoxycorticosterone (DOC), testosterone, pregnenolone, 17-hydroxypregnenolone (17Pregn), cortisol and cortisone. Chromosomal sex was determined by karyotype and gestational age by biometric measurements.

RESULTS

Analysis of "control" samples showed a statistically significant difference for D4 and testosterone levels according to foetal sex. Cortisol, corticosterone, and DOC had lower concentrations before 20 GW than after 20 GW, whereas 17Pregn and pregnenolone had higher concentrations before 20 GW. This allowed us to establish age- and sex-dependant reference values. We observed higher 21OH, 17Pregn, D4 and testosterone levels in females 21OHD than female controls. The ratios 17OHP/17Pregn, D4/DHEA and 11OH/17OHP appeared discriminant for the diagnosis of 21OHD.

CONCLUSION

Our study provides information on foetal steroidogenesis and suggests reference values for 12 steroids during pregnancy. This allows a prenatal diagnosis of 21-hydroxylase deficiency within 24 hours and might be useful in the diagnosis of other variations of sex development (VSD).

Impact of Gestational and Postmenstrual Age on Excretion of Fetal Zone Steroids in Preterm Infants Determined by Gas Chromatography-Mass Spectrometry

CONTEXT

Fetal zone steroids (FZSs) are excreted in high concentrations in preterm infants. Experimental data suggest protective effects of FZSs in models of neonatal disease.

OBJECTIVE

We aimed to characterize the postnatal FZS metabolome of well preterm and term infants.

METHODS

Twenty-four-hour urinary FZS excretion rates were determined in early preterm (<30 weeks' gestation), preterm (30-36 weeks), and term (>37 weeks) infants. Pregnenolone and 17-OH-pregnenolone metabolites (n = 5), and dehydroepiandrosterone sulfate and metabolites (n = 12) were measured by gas chromatography mass spectrometry. Postnatal concentrations of FZSs were compared with already published prenatal concentrations in amniotic fluid.

RESULTS

Excretion rates of total FZSs and most of the single metabolites were highest in early preterm infants. In this group, excretion rates approach those of term infants at term equivalent postmenstrual age. Preterm infants of 30-36 weeks had more than half lower median excretion rates of FZSs than early preterm infants at the same time of postmenstrual age. Postnatal concentrations of FZSs were partly more than 100-fold higher in all gestational age groups than prenatal concentrations in amniotic fluid at midgestation.

CONCLUSION

The excretion rates of FZSs as a proxy of the involution of the fetal zone of the most immature preterm infants approached those of term infants at term equivalent. In contrast, the fetal zone in more mature preterm infants undergoes more rapid involution. These data in exclusively well neonates can serve as a basis to investigate the effects of illness on the FZS metabolome in future studies.

Targeted LC-MS/MS analysis of steroid glucuronides in human urine

Conjugation with glucuronic acid is one of the major metabolic reactions in human steroid hormone catabolism. Recently, increasing interest has been raised concerning the biological roles of steroid glucuronides. We have therefore developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of 15 urinary steroid hormone glucuronides in human urine: androsterone glucuronide (An-G), etiocholanolone glucuronide (Etio-G), epiandrosterone glucuronide (epiAn-G), dihydrotestosterone glucuronide (DHT-G), dehydroepiandrosterone glucuronide (DHEA-G), testosterone glucuronide (T-G), epitestosterone glucuronide (epiT-G), estrone glucuronide (E1-3 G), 17β-estradiol 17-glucuronide (E2-17 G), 17β-estradiol 3-glucuronide (E2-3 G), estriol 16-glucuronide (E3-16 G), pregnenolone glucuronide (Preg-G), tetrahydro-11-deoxycorticosterone 3-glucuronide (THDOC-3 G), cortisol 21-glucuronide (F-G) and pregnanediol glucuronide (PD-G). Sample workup included protein precipitation and solid phase extraction. Internal standards were used to correct for the loss of analytes during sample preparation and analysis. The method showed good linearity (R²≥0.99) and recovery ranged from 89.6 % to 113.8 %. Limit of quantification ranged from 1.9 nmol/L for F-G to 21.4 nmol/L for An-G. Intra-day and inter-day accuracy and precision were below 15 % for all quality controls. The method was successfully applied to 67 urine samples from children and adolescents in whom total concentrations of free and conjugated steroids had been previously determined by GC-MS after enzymatic hydrolysis. Free and sulfated steroids were also measured by LC-MS/MS. In general, the sums of the respective glucuronidated, sulfated and free forms of an analyte corresponded well with its total amount determined after enzymatic hydrolysis by GC-MS. Regarding the most prominent steroid metabolites, the total mean levels of androsterone and etiocholanolone showed an increase up to 5820.0 nmol/L and 4017.8 nmol/L in the group of 15-20 year-old children, respectively. Glucuronide conjugates (4374.3 nmol/L and 3588.5 nmol/L, respectively) dominated. DHEA was excreted mostly as sulfate (0-1 month of age: 184.5 nmol/L; 15-20 years of age: 1618.4 nmol/L) in all age groups. Cortisol was present predominantly as sulfate (mean: 173.8 nmol/L) in newborns. Levels of sulfated cortisol decreased with age, its glucuronidated form increased. The levels of free cortisol were relatively constant throughout childhood. Sex hormones were preferably excreted as glucuronides. In general, steroid hormone metabolites were conjugated to various extents with glucuronic acid or sulfuric acid and their ratio changed over lifetime.

Masculinized Second-to-Fourth Digit Ratio (2D:4D Ratio) Is Associated With Lower Cortisol Response in Infant Female Rhesus Monkeys (Macaca mulatta)

The second-to-fourth digit ratio (2D:4D ratio) is considered a postnatal proxy measure for the degree of prenatal androgen exposure (PAE), which is the primary factor responsible for masculinizing the brain of a developing fetus. Some studies suggest that the organizational effects of PAE may extend to the hypothalamic-pituitary-adrenal (HPA) axis response to stress. This study investigates the relationship between 2D:4D ratio and HPA axis functioning using a rhesus monkey (Macaca mulatta) model. Subjects were N = 268 (180 females, 88 males) rhesus monkey infants (3–4 months of age). Plasma cortisol concentrations were assayed from two blood samples obtained during a 25-h experimental social separation stressor at 2- and 7-h post-separation. Subjects’ 2D:4D ratio was measured later in life (M_age = 6.70 years). It was hypothesized that infant rhesus monkeys that exhibited a more masculine-like 2D:4D ratio would show lower levels of circulating cortisol after a social separation and relocation stressor. The results showed that there was a sex difference in the left-hand 2D:4D ratio. The results also showed that there was an overall sex difference in cortisol concentrations and that female, but not male, monkeys that exhibited a more masculine-like right- and left-hand 2D:4D ratio exhibited lower mean stress-induced cortisol concentrations early in life. These findings suggest that higher levels of prenatal androgens in females, as measured by 2D:4D ratio, may be related to an attenuated HPA axis stress-response, as measured by plasma cortisol levels. To the extent that these findings generalize to humans, they suggest that the organizational effects of PAE extend to the infant HPA axis, modulating the HPA axis response, particularly in females.

Study on amniotic fluid metabolism in the second trimester of Trisomy 21

BACKGROUND

Trisomy 21 is a common aneuploid condition in humans and accounts for approximately one quarter of all aneuploid live births. To date, early diagnosis of Trisomy 21 remains a challenging task. Metabolomics may prove an innovative tool to study the early pathophysiology of Trisomy 21 at a functional level.

METHODS

Ultra-performance liquid chromatography coupled with mass spectrometer (UPLC-MS) was used for untargeted metabolomic analysis of amniotic fluid samples from women having normal and trisomy 21 fetuses.

RESULTS

Many significantly changed metabolites were identified between amniotic fluid samples from Trisomy 21 pregnancies and normal euploid pregnancies, such as generally lower levels of several steroid hormones and their derivatives, higher levels of glutathione catabolites coupled with lower levels of gamma-glutamyl amino acids, and increased levels of phospholipid catabolites, sugars, and dicarboxylic acids. The identification of a human milk oligosaccharide in amniotic fluid may worth further investigation, since confirmation of this observation may have significant implications for regulation of fetal development.

CONCLUSIONS

The metabolisms in amniotic fluid from Trisomy 21 and normal pregnancies are quite different, and some of the significantly changed metabolites may be considered as candidates of early diagnostic biomarkers for Trisomy 21.

Determination of the steroid profile in alternative matrices by liquid chromatography tandem mass spectrometry

The simultaneous determination of a broad panel of steroids provides more accurate information about the hormonal status than the detection of a single hormone. For that reason, the determination of the steroid profile, i.e. the endogenous steroid hormones and their main metabolites, has become the most powerful tool for the study of hormonal imbalances. The usefulness of the evaluation of the steroid profile in urine and plasma is widely accepted. However, despite its broad potential applicability, the evaluation of the whole steroid profile in alternative matrices such as amniotic fluid, saliva and breast milk remains almost unexplored. In this research we developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of several steroids and their metabolites in amniotic fluid (28 analytes), saliva (15) and breast milk (12). Sample preparation, chromatographic conditions and mass spectrometric conditions (e.g. ionization species or ion source parameters) were optimized. The method was shown to be linear in the range of endogenous concentrations for all studied metabolites. Intra- and inter-assay accuracies were between 80% and 120% while intra- and inter-precisions were below 20% for all analytes in all matrices. The applicability of the method was evaluated by the comparison between the concentration ranges obtained in healthy volunteers (n = 30 per matrix) and the scarce data previously reported in literature. The concentration ranges for several analytes are reported for the first time. The present methodology represents a useful tool for the comprehensive evaluation of the steroid profile in alternative matrices and can be applicable for different clinical purposes.

Characterizing the steroidal milieu in amniotic fluid of mid-gestation: A GC-MS study

Intact steroid hormone biosynthesis is essential for growth and development of the human fetus and embryo. In the present study, gas chromatography-mass spectrometry was employed to characterize the steroidal milieu in amniotic fluid (n = 65; male: female = 35: 30) of mid-gestation (median: 18.8th week, range: 16.0th - 24.6th week) by a comprehensive targeted steroid hormone metabolomics approach. The levels of 52 steroids including pregnenolone and 17-OH-pregnenolone metabolites, dehydroepiandrosterone (DHEA) and its metabolites, progesterone and 17-OH-progesterone metabolites, sex hormones as well as corticosterone and cortisol metabolites were measured. The dominating steroids were the group of pregnenolone and 17-OH-pregnenolone metabolites (mean ± SD: 138.0 ± 59.3 ng/mL), followed by the group of progesterone and 17-OH-progesterone metabolites (107.3 ± 44.3 ng/mL), and thereafter DHEA and its metabolites (97.1 ± 56.5 ng/mL). With respect to sex steroids, only testosterone showed a significantly higher value in male fetuses (p < 0.0001). Of all estrogen metabolites, estriol showed by far the highest concentrations (33.2 ± 26.1 ng/mL). Interestingly, cortisol metabolites were clearly present (59.6 ± 13.6 ng/mL) though fetal de novo synthesis of cortisol is assumed to start from gestational 28th week onwards. Our comprehensive characterization of the steroidal milieu in amniotic fluid of mid-gestation shows presence of all relevant classes of steroid hormones and provides reference data. We conclude that the steroidal milieu in amniotic fluid mirrors the steroidome of the feto-placental unit.