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Biomedical subjects

Janet E Hall

Publications and source records attributed to Janet E Hall.

At least 19 recordsLinked to original sources

Implementing secondary findings analysis in a genetic and environmental research study.

PURPOSE: Optimizing return of secondary findings (SFs) in research settings requires an understanding of the complexities and challenges. METHODS: Genome sequence was generated for 4737 participants in a genetic and environmental health study, and 4630 of them consented to SF return. Variants in the American College of Medical Genetics and Genomics v3.0 genes were classified using the American College of Medical Genetics and Genomics/Association for Molecular Pathology criteria with ClinGen-approved modifications. RESULTS: Eighty-six variants were eligible for return to 102 participants. Average time to initial recontact attempt was 5.8 years. Recontact attempts reached 95 of 102 individuals. Results were returned to 57 participants. The remainder passively declined (25), actively declined (11), were lost to follow-up (5), were deceased (3), or had prior knowledge of the result (1). Return of results was positively associated with education status (2 × 3 C2, P = .0035). CONCLUSION: The interest in receiving SFs was high at the time of consenting, but a clinically validated result was returned to just over half of the individuals with an SF. Approximately 1 in 3 participants with an SF who had consented to receive them subsequently actively or passively declined receipt of the result. Given the health importance of return of SF, minimizing the time from consent to results return and tailoring outreach to education level may optimize uptake of SF return.

Adult↗

Longitudinal follow-up of reproductive and metabolic features of valproate-associated polycystic ovarian syndrome features: A preliminary report.

BACKGROUND: In the Systematic Treatment Enhancement Program for Bipolar Disorder, we showed that valproate is associated with new-onset menstrual-cycle irregularities and hyperandrogenism in 10.5% of 86 women. We now determine whether polycystic ovarian syndrome (PCOS) features reverse on valproate discontinutation. METHODS: Women with valproate-associated PCOS and those at risk for PCOS (valproate use < or =6 months) were re-evaluated for PCOS. RESULTS: Follow-up (mean 17 months) assessments were completed in 14 women (5 with treatment-emergent PCOS, 9 on valproate < or =6-month). Of seven women who developed valproate-associated PCOS, PCOS reproductive features remitted in three of four discontinuing valproate and persisted in all 3 continuing valproate. Menstrual-cycle irregularities improved among valproate-discontinuers whose PCOS features remitted (p = 0.01). There was a trend toward lower serum testosterone (p = 0.06). Body-weight and polycystic ovarian morphology did not change. CONCLUSIONS: In the first longitudinal bipolar-disorder study of valproate-associated PCOS, most valproate-discontinuers had improved reproductive features of PCOS despite static body-weight.

Adolescent↗

Mutations in fibroblast growth factor receptor 1 cause both Kallmann syndrome and normosmic idiopathic hypogonadotropic hypogonadism.

Mutations in KAL1 and FGFR1 cause Kallmann syndrome (KS), whereas mutations in the GNRHR and GPR54 genes cause idiopathic hypogonadotropic hypogonadism with normal olfaction (nIHH). Mixed pedigrees containing both KS and nIHH have also been described; however, the genetic cause of these rare cases is unknown. We examined the FGFR1 gene in seven nIHH subjects who either belonged to a mixed pedigree (n = 5) or who had associated midline defects (n = 2). Heterozygous FGFR1 mutations were found in three of seven unrelated nIHH probands with normal MRI of the olfactory system: (i) G237S in an nIHH female and a KS brother; (ii) (P722H and N724K) in an nIHH male missing two teeth and his mother with isolated hyposmia; and (iii) Q680X in a nIHH male with cleft lip/palate and missing teeth, his brother with nIHH, and his father with delayed puberty. We show that these mutations lead to receptor loss-of-function. The Q680X leads to an inactive FGFR1, which lacks a major portion of the tyrosine kinase domain (TKD). The G237S mutation inhibits proper folding of D2 of the FGFR1 and likely leads to the loss of cell-surface expression of FGFR1. In contrast, the (P722H and N724K) double mutation causes structural perturbations in TKD, reducing the catalytic activity of TKD. We conclude that loss-of-function mutations in FGFR1 cause nIHH with normal MRI of the olfactory system. These mutations also account for some of the mixed pedigrees, thus challenging the current idea that KS and nIHH are distinct entities.

Amino Acid Substitution↗

Valproate is associated with new-onset oligoamenorrhea with hyperandrogenism in women with bipolar disorder.

BACKGROUND: Preliminary evidence suggests that valproate is associated with isolated features of polycystic ovarian syndrome (PCOS), while contradictory data support an association between epilepsy and PCOS. The development of PCOS features after initiation of valproate was therefore examined in women with bipolar disorder using a standardized definition of PCOS. METHODS: Three hundred women 18 to 45 years old with bipolar disorder were evaluated for PCOS at 16 Systematic Treatment Enhancement for Bipolar Disorder sites. A comparison was made between the incidence of hyperandrogenism (hirsutism, acne, male-pattern alopecia, elevated androgens) with oligoamenorrhea that developed while taking valproate versus other anticonvulsants (lamotrigine, topiramate, gabapentin, carbamazepine, oxcarbazepine) and lithium. Medication and menstrual cycle histories were obtained, and hyperandrogenism was assessed. RESULTS: Among 230 women who could be evaluated, oligoamenorrhea with hyperandrogenism developed in 9 (10.5%) of 86 women on valproate and in 2 (1.4%) of 144 women on a nonvalproate anticonvulsant or lithium (relative risk 7.5, 95% confidence interval [CI] 1.7-34.1, p = .002). Oligoamenorrhea always began within 12 months of valproate use. CONCLUSIONS: Valproate is associated with new-onset oligoamenorrhea with hyperandrogenism. Monitoring for reproductive-endocrine abnormalities is important when starting and using valproate in reproductive-aged women. Prospective studies are needed to elucidate risk factors for development of PCOS on valproate.

Adolescent↗

Inverse relationship between luteinizing hormone and body mass index in polycystic ovarian syndrome: investigation of hypothalamic and pituitary contributions.

CONTEXT: Patients with polycystic ovarian syndrome (PCOS) have increased LH relative to FSH, but LH is modified by body mass index (BMI). OBJECTIVE: The objective of the study was to determine whether the impact of BMI on neuroendocrine dysregulation in PCOS is mediated at the hypothalamic or pituitary level. PARTICIPANTS/INTERVENTIONS/SETTING: Twenty-four women with PCOS across a spectrum of BMIs underwent frequent blood sampling, iv administration of GnRH (75 ng/kg), and sc administration of the NAL-GLU GnRH antagonist (5 microg/kg) in the General Clinical Research Center at an academic hospital. MAIN OUTCOME MEASURES: LH pulse frequency and LH response to submaximal GnRH receptor blockade were used as measures of hypothalamic function; LH response to GnRH was used as a measure of pituitary responsiveness. RESULTS: BMI was negatively correlated with mean LH, LH/FSH, and LH pulse amplitude. There was no effect of BMI on LH pulse frequency. Percent inhibition of LH was decreased in PCOS, compared with normal women (53.9 +/- 1.5 vs. 63.1 +/- 4.1, respectively; P < 0.01), suggesting an increase in the amount of endogenous GnRH, but was not influenced by BMI. Pituitary responsiveness to GnRH was inversely correlated with BMI (peak LH, R = -0.475, P < 0.02; and LH area under the curve R = -0.412, P < 0.02). CONCLUSIONS: LH pulse frequency and quantity of GnRH are increased in PCOS, but there is no influence of BMI on either marker of hypothalamic function. The pituitary response to a weight-based dose of GnRH is inversely related to BMI in PCOS. These studies suggest that the effect of BMI on LH is mediated at a pituitary and not a hypothalamic level in PCOS.

Adult↗

Absence of apparent circadian rhythms of gonadotropins and free alpha-subunit in postmenopausal women: evidence for distinct regulation relative to other hormonal rhythms.

Aging is associated with a decrease in gonadotropin levels in postmenopausal women (PMW) and is also associated with alterations in a number of circadian rhythms. The goals of this study were to determine the presence of circadian rhythms of gonadotropins and glycoprotein free alpha-subunit (FAS) in young and old PMW. Healthy, euthyroid PMW, ages 45 to 55 years (n = 11) and 70 to 80 years (n = 11), were admitted in the morning to start a 24-h constant routine of light, temperature, position, and activity. Subjects remained awake and semirecumbent for the duration of the study and were fed hourly snacks, and activity was monitored continuously. Blood was sampled every 5 min for two 8-h periods corresponding to the estimated acrophase and nadir of the temperature rhythm. Luteinizing hormone (LH) and FAS were measured in all samples and follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), and cortisol in 20-min serum pools. Mean LH (p < 0.001), FSH (p < 0.002), and FAS (p < 0.002) were lower in older compared with younger PMW. Day/night differences in cortisol and TSH (p < 0.001) were present in all subjects. However, there were no day/night differences in LH in younger or older PMW or in FSH in younger or older PMW. There were no day/night differences in mean FAS in younger or older PMW or in FAS pulse frequency or amplitude. Thus, in controlled studies in which differences in cortisol and TSH were demonstrated, there were no day/night differences in LH, FSH, or FAS in PMW. These studies suggest that despite evidence of intact circadian rhythms of cortisol and TSH, gonadotropin secretion does not appear to follow a circadian pattern in PMW. Thus, the age-related decline in gonadotropin secretion in PMW is not associated with a dampening of circadian rhythmicity. The absence of day/night differences in FAS suggests that GnRH plays a more prominent role in FAS regulation than does thyrotropin-releasing hormone in PMW.

Aged↗

Coding sequence analysis of GNRHR and GPR54 in patients with congenital and adult-onset forms of hypogonadotropic hypogonadism.

OBJECTIVE: To determine the frequency of rare nucleotide variants in GNRHR and GPR54 in a large cohort of probands (n = 166) with normosmic idiopathic hypogonadotropic hypogonadism (nIHH), characterized by mode of inheritance, testicular volume, and presence or absence of endogenous LH pulsations. METHODS: Whenever possible, probands answered detailed questionnaires, underwent full physical exams, and underwent q 10-min frequent blood sampling for LH. Exons segments for GNRHR and GPR54 were screened for mutations. Nucleotide changes were identified as rare variants if they occurred at less than 1% frequency in an ethnically matched control population. RESULTS: Sixty-two percent of male probands were classified as sporadic, meaning that no other family members had delayed puberty or nIHH. In contrast, 61% of female probands were from familial pedigrees, with either autosomal dominant or autosomal recessive inheritance. Patients displayed a broad spectrum of disease severity based on testicular size and endogenous LH pulsations. Twenty-four rare variants were identified in GNRHR (within 15 probands) and seven rare variants in GPR54 (within five probands). CONCLUSIONS: Rare variants in GNRHR are more common than GPR54 in a nIHH population.

Female↗

Should symptomatic menopausal women be offered hormone therapy?

UNLABELLED: Many physicians remain uncertain about prescribing hormone therapy for symptomatic women at the onset of menopause. The American Society for Reproductive Medicine (ASRM) convened a multidisciplinary group of healthcare providers to discuss the efficacy and risks of hormone therapy for symptomatic women, and to determine whether it would be appropriate to treat women at the onset of menopause who were complaining of menopausal symptoms. MAJOR FINDINGS: Numerous controlled clinical trials consistently demonstrate that hormone therapy, administered via oral, transdermal, or vaginal routes, is the most effective treatment for vasomotor symptoms. Topical vaginal formulations of hormone therapy should be preferred when prescribing solely for the treatment of symptoms of vulvar and vaginal atrophy. Data from the Women's Health Initiative indicate that the overall attributable risk of invasive breast cancer in women receiving estrogen plus progestin was 8 more cases per 10,000 women-years. No increased risk for invasive breast cancer was detected for women who never used hormone therapy in the past or for those receiving estrogen only. Hormone therapy is not effective for the treatment of cardiovascular disease and that the risk of cardiovascular disease with hormone therapy is principally in older women who are considerably postmenopause. CONCLUSIONS: Healthy symptomatic women should be offered the option of hormone therapy for menopausal symptoms. Symptom relief with hormone therapy for many younger women (at the onset of menopause) with menopausal symptoms outweighs the risks and may provide an overall improvement in quality of life. Hormone therapy should be individualized for symptomatic women. This involves tailoring the regimen and dose to individual needs.

Aged↗

Selective theca cell dysfunction in autoimmune oophoritis results in multifollicular development, decreased estradiol, and elevated inhibin B levels.

We describe the clinical course of three women with presumptive autoimmune oophoritis who developed multiple follicles but very low to undetectable estradiol levels. Multiple follicles developed spontaneously in all subjects and during pulsatile GnRH treatment for ovulation induction in subject 1. The development of multiple dominant follicles was accompanied by LH levels in the postmenopausal range and FSH levels at the upper limit for premenopausal women. Serum inhibin B levels were elevated appropriately in the setting of multifollicular development, but estradiol levels remained low. Measurement of estradiol precursors demonstrated androstenedione and estrone levels below the 95th percentile in normal women. Adrenal cortical antibodies, and antibodies to 21-hydroxylase and P450 side chain cleavage enzymes were identified in all subjects. All subjects met the criteria for premature ovarian failure during follow-up. Subject 1 later developed adrenal failure, whereas subject 3 had adrenal failure at the time of the study. These subjects elucidate the hormonal pattern in autoimmune oophoritis, before the full criteria for premature ovarian failure are met. The elevated inhibin A and B levels, which accompany the development of multiple small and dominant follicles in these women, suppress FSH relative to LH levels, virtually independent of estradiol. These data provide further evidence for an important role of inhibin B and inhibin A in the negative feedback control of FSH. In addition, the normal inhibin A and inhibin B production in the absence of estradiol precursors and estradiol provide insight into the selective dysfunction of the theca cells in autoimmune oophoritis.

Adolescent↗

Brief wake episodes modulate sleep-inhibited luteinizing hormone secretion in the early follicular phase.

To determine the influence of sleep, sleep stage, and time of day on the dynamics of pulsatile LH secretion in the early follicular phase (EFP) of the menstrual cycle, 11 normal women underwent simultaneous polysomnographic monitoring of sleep and measurement of LH in frequent sampling studies during a 40-h protocol that consisted of one night of normal sleep and one night of sleep deprivation followed by an afternoon nap. The interpulse interval of LH was longer during sleep than wake whether it occurred at night or during the day (P < 0.002), implying a decrease in GnRH pulse frequency associated with sleep in the EFP. LH pulse amplitude was greater during sleep than wake (P < 0.001) and greater pulse amplitudes were associated with longer interpulse intervals during sleep (P < 0.005), but not wake. An interaction between sleep and time of day was observed for mean LH, with lower mean LH levels during sleep than wake at night (P < 0.02), but not during the day. Wakefulness was more likely to be associated with an LH pulse than were stages I/II, III/IV (slow wave), or rapid eye movement sleep (P < 0.005). In addition, the probability of wakefulness within the sleep episode increased 5-15 min before the onset of LH pulses (relative to randomly selected nonpulse LH; P < 0.05), suggesting that wakefulness was the primary event. In the absence of sleep, there was an effect of time of day on mean LH (P < 0.02) and LH pulse amplitude (P < 0.03), with greatest values seen during the evening. In conclusion, in the EFP, inhibition of LH pulse frequency is related to sleep rather than time of day. During periods of sleep, LH pulses occur most commonly in association with brief awakenings, suggesting that interruptions from sleep allow escape from the inhibitory effect of sleep on pulsatile GnRH secretion. A separate effect of time of day on LH pulse dynamics in the absence of sleep was also observed with evening augmentation of LH pulse amplitude and mean level; however, additional studies will be required to determine whether this represents a true circadian effect.

Adult↗

Psychosocial risks associated with multiple births resulting from assisted reproduction.

OBJECTIVE: To determine if increased psychosocial risks are associated with each increase in birth multiplicity (i.e., singleton, twin, triplet) resulting from assisted reproduction. DESIGN: Stratified random sample (n = 249). SETTING: An academic teaching hospital and private practice infertility center. PATIENT(S): Mothers raising 1- to 4-year-old children (n = 128 singletons, n = 111 twins, and n = 10 triplets) conceived through assisted reproduction. INTERVENTION(S): Self-administered, mailed survey. MAIN OUTCOME MEASURE(S): Scales measuring material needs, quality of life, social stigma, depression, stress, and marital satisfaction. RESULT(S): Using multivariate logistic regression models, for each additional multiple birth child, the odds of having difficulty meeting basic material needs more than tripled and the odds of lower quality of life and increased social stigma more than doubled. Each increase in multiplicity was also associated with increased risks of maternal depression. CONCLUSION(S): To increase patients' informed decision-making, assisted reproduction providers might consider incorporating a discussion of these risks with all patients before they begin fertility treatment, and holding the discussion again if the treatment results in a multiple gestation. These data may also help providers to identify appropriate counseling, depression screening, and supports for patients with multiple births.

Adult↗

Relationship of estradiol and inhibin to the follicle-stimulating hormone variability in hypergonadotropic hypogonadism or premature ovarian failure.

Recent studies have demonstrated the presence of ovarian follicular development in up to 78% of women with premature ovarian failure (POF). The purpose of this study was to examine the control of FSH by estradiol and inhibin secretion from these follicles. Weekly blood samples were collected in conjunction with assessment of ovarian follicle development by ultrasound for at least 12 wk in 49 subjects with POF. Results were compared with those of 44 normal cycling women. Ovulatory cycles occurred in 24 subjects (49%) with POF. These ovulatory cycles were characterized by higher FSH and lower inhibin B and inhibin A levels, whereas estradiol levels were higher compared with those in normal women. Follicles developed in the absence of ovulation in 18 women (37%) with POF, whereas the ovaries were inactive in seven women (14%). FSH levels were lower in POF women with ovulatory or anovulatory follicle development compared with levels in women with inactive ovaries. These findings demonstrate that ovulatory cycles in women with POF are characterized by a persistent elevation in FSH compared with levels in normal cycling women. The association of increased FSH with lower levels of inhibin B and inhibin A, but higher estradiol levels provides additional evidence for an important physiological role of the inhibins in the negative feedback control of FSH. These data also demonstrate the variability in FSH levels as a function of underlying follicular development in women with POF.

Anovulation↗

Neuroendocrine physiology of the early and late menopause.

Hormonal integration of the reproductive system is dramatically affected by reproductive aging. The progressive loss of ovarian follicles with normal aging is accompanied by an initial decrease in inhibin B and a concomitant increase in follicle-stimulating hormone. Subsequently, inhibin A and progesterone decrease, where as estradiol levels are maintained and often increase. In the late reproductive stage, cycles remain regular whereas the early and late menopausal transition are characterized by irregular cycles and often dramatic swings in estradiol and gonadotropin levels. Studies in younger and older postmenopausal women suggest that there are age-related changes in the neuroendocrine axis that are independent of the changing ovarian hormonal milieu of the menopausal transition but may contribute to the end of reproductive life.

Aging↗

Polycystic ovarian morphology with regular ovulatory cycles: insights into the pathophysiology of polycystic ovarian syndrome.

To determine the relevance of polycystic ovarian morphology (PCOM) to the pathophysiology of polycystic ovarian syndrome (PCOS), biochemical features associated with PCOS were examined in 68 women with an established history of regular ovulatory cycles and no clinical evidence of hyperandrogenism. Ovarian morphology was objectively assessed by pelvic ultrasound. LH, FSH, estradiol (E(2)), testosterone (T), androstenedione (Delta(4)A), SHBG, and dehydroepiandrosterone sulfate (DHEAS) were measured at baseline in the early follicular phase (EFP) in all subjects. LH, FSH, E(2), and progesterone (P(4)) were then measured daily for a complete menstrual cycle in 16 women with normal ovarian morphology and in 26 women with PCOM. T, Delta(4)A, SHBG, and DHEAS levels were measured in pools of three daily samples in each of the EFP, midcycle, and midluteal phases. An additional 26 normal women (13 with normal ovarian morphology and 13 with PCOM) were studied in the EFP to assess pulsatile LH secretion, insulin and glucose levels, and the ovarian response to human chorionic gonadotropin. At baseline, there were no differences in body mass index or hirsutism scores between women with PCOM and normal ovaries. In daily samples across the menstrual cycle LH, FSH, E(2), and P(4) did not differ between women with PCOM and those with normal ovaries, and there was no difference in LH pulse amplitude or frequency in the EFP frequent sampling studies. In women with PCOM, T (P < 0.01), free T (P < 0.005), and DHEAS (P < 0.01) levels were higher at baseline in the EFP, and SHBG was lower (P < 0.05). Differences in Delta(4)A did not reach significance (P = 0.14). T, free T, Delta(4)A, and DHEAS were also increased in PCOM across the menstrual cycle (P < 0.05). In addition, 17-hydroxyprogesterone (P < 0.02), Delta(4)A (P < 0.01), and T (P < 0.01) responses to human chorionic gonadotropin were greater in women with PCOM. Fasting glucose was not different between the two groups, but fasting insulin was higher (P < 0.02) in PCOM women as was insulin resistance calculated from homeostatic model assessment (P < 0.01). These studies demonstrate that PCOM in nonhirsute women with documented ovulatory cycles is associated with normal E(2), P(4), and gonadotropin dynamics, but higher androgen and insulin levels and lower SHBG levels. Taken together, these findings suggest that PCOM with ovulatory cycles exists as a discrete entity, represents the mildest form of ovarian hyperandrogenism, and is associated with greater insulin resistance than in women with normal ovarian morphology. The absence of any neuroendocrine abnormality in women with PCOM and ovulatory cycles suggests that gonadotropin dysfunction is not required for increased androgen secretion, but may be critical for development of the anovulatory disorder associated with PCOS.

Adult↗

GNRHR mutations in a woman with idiopathic hypogonadotropic hypogonadism highlight the differential sensitivity of luteinizing hormone and follicle-stimulating hormone to gonadotropin-releasing hormone.

Mutations in the GnRH receptor gene (GNRHR) are a cause of idiopathic hypogonadotropic hypogonadism. We describe a normosmic female subject with congenital idiopathic hypogonadotropic hypogonadism in whom treatment with pulsatile GnRH resulted in an unusual response. The subject not only required an increased dose of pulsatile GnRH for ovarian follicular development, but LH secretion did not increase appropriately, estradiol levels remained low, and she did not ovulate spontaneously. Sequencing of the GNRHR coding sequence revealed compound heterozygous mutations leading to amino acid substitutions [N10K+Q11K] and P320L. The introduction of the P320L mutation into the GnRH receptor led to failure of detectable ligand binding and failure of stimulation of inositol phosphate production and gonadotropin subunit gene promoter activity in response to GnRH in transiently transfected cells. The [N10K+Q11K] mutation resulted in reduced binding of a GnRH agonist to 25% of the wild-type receptor. In addition, the EC(50) value for GnRH stimulation of inositol phosphate production was significantly increased, and the dose-response curves for stimulation of alpha gonadotropin subunit, LHbeta, and FSHbeta gene transcription by GnRH were similarly shifted to the right. Stimulation of FSHbeta gene transcription was more sensitive to GnRH than LHbeta for both wild-type and [N10K+Q11K] GnRH receptors, resulting in a greater loss of LHbeta stimulation than FSHbeta by the [N10K+Q11K] mutant at any given submaximal GnRH concentration. We propose that the mutations in the GnRH receptor result in a rightward shift of the dose-response curves of gonadotropin responses to pulsatile GnRH in the subject and unmask the differential sensitivities of LH and FSH to GnRH, resulting in low LH and estradiol levels despite appropriate FSH secretion and follicular growth.

Adult↗

Social stigma and compounded losses: quality-of-life issues for multiple-birth families.

OBJECTIVE: To determine the quality-of-life domains most impacted by multiple births. DESIGN: Focus groups, qualitative research. SETTING: Human volunteers in a medical research environment.Forty-three mothers, 29 raising multiple-birth children, 13 raising singletons, identified from random and convenience samples. INTERVENTION: None. MAIN OUTCOME MEASURE(S): Maternal self-reports of the psychosocial sequelae of multiple or singleton births, based on qualitative data analysis of transcribed group discussions. RESULT(S): The quality-of-life domains that were most impacted by raising multiple birth children were social stigma, pregnancy loss, marital satisfaction, children's health, unmet family needs, parenting stress, maternal depression, and the infertility experience. CONCLUSION(S): Qualitative methods identified two novel quality-of-life domains in iatrogenic multiple birth families: social stigma and compounded losses. An unexpected finding was the potential for increased marital solidification as parents coped with the inordinate stresses of multiple births. As anticipated, children's health, unmet family needs, maternal depression, and parental stress were key areas of concern. In addition, the infertility experience had a lasting impact. These findings are significant, given that at least 38% of all assisted conceptions result in a multiple birth. This study lays the groundwork for further research on the impact of iatrogenic multiple births.

Abortion, Spontaneous↗

Control of follicle-stimulating hormone by estradiol and the inhibins: critical role of estradiol at the hypothalamus during the luteal-follicular transition.

To test the hypothesis that estradiol, inhibin A, and inhibin B contribute differentially to FSH negative feedback in specific phases of the menstrual cycle, daily blood samples were obtained across a control cycle and after selective estrogen blockade with tamoxifen. To examine the site of estradiol-negative feedback in control and tamoxifen treatment cycles, early follicular phase GnRH (free alpha-subunit) pulse frequency was assessed in normal women, and FSH levels were examined in GnRH-deficient women in whom hypothalamic output was fixed with GnRH administration. FSH was higher in the early follicular phase in the presence of estrogen receptor blockade (15.7 +/- 3.1 vs. 13.2 +/- 1.9 IU/liter; P < 0.05) but was not increased in the late follicular phase. In the luteal phase, FSH was elevated (10.1 +/- 0.7 vs. 7.3 +/- 0.6 IU/liter; P < 0.01). In normal women, free alpha-subunit pulse frequency increased (7.3 +/- 0.4 vs. 4.8 +/- 0.4 pulses per 8 h; P < 0.003), but in GnRH-deficient women, there was no FSH increase (11.1 +/- 1.6 vs. 12.5 +/- 3.6 IU/liter) in the early follicular phase in the presence of estrogen blockade. In conclusion, estradiol exerts a greater role over inhibin in FSH-negative feedback regulation during the luteal phase and the luteal-follicular transition. In contrast, inhibin A and/or B plays a more critical role as the follicular phase progresses. In addition, these studies support a primary if not exclusive hypothalamic site of estrogen-negative feedback in the early follicular phase.

Estradiol↗

Serum inhibin B in polycystic ovary syndrome: regulation by insulin and luteinizing hormone.

Inhibin B is a product of the granulosa cells of growing preantral and antral follicles. Despite the large ovarian volume and increased follicle number typically detected in women with polycystic ovary syndrome (PCOS), previous studies demonstrate that inhibin B is not elevated as would be expected in PCOS, but is inversely correlated with body mass index (BMI). We therefore hypothesized that inhibin B levels in women with PCOS are regulated by a factor related to BMI. Thus, LH, sex steroids, and metabolic parameters were measured in 50 anovulatory PCOS subjects in pools constituted from equal aliquots of serum drawn every 10 min for 4 h and were correlated with inhibin B. Based on the results of these correlative studies, inhibin B regulation by human chorionic gonadotropin (hCG) and insulin was tested directly. In PCOS subjects, inhibin B correlated inversely with BMI (r = -0.413; P < 0.004) and fasting insulin (r = -0.409; P < 0.004). Inhibin B also correlated directly with pool LH (r = 0.419; P < 0.003), LH pulse amplitude (r = 0.512; P < 0.0001), and SHBG (r = 0.429; P < 0.003). The relationships demonstrated for inhibin B were not demonstrated for inhibin A, nor were they evident in normal subjects. To determine whether the correlations represent regulation of inhibin B, i.e. stimulation of inhibin B by LH or suppression by insulin, two interventional studies were performed. In the first study hCG (5000 U) was administered to PCOS subjects (n = 15) to mimic the effects of LH. Inhibin B was not increased, but was significantly reduced 24 h after hCG administration (223.8 +/- 21.3 vs. 152.4 +/- 15.9 pg/ml; P < 0.0005). In the second study, diazoxide (100 mg every 8 h) was administered for 3 d to PCOS subjects (n = 9). Inhibin B increased (85.4 +/- 12.4 to 136.6 +/- 18.8 pg/ml; P < 0.05) in association with a decrease in the insulin area under the curve (104 +/- 29 to 83 +/- 22 nmol/liter.min; P < 0.05) induced by diazoxide. In PCOS subjects, inhibin B demonstrated significant relationships with BMI and factors related to BMI, including LH, insulin, and SHBG. Although LH was associated with inhibin B, hCG administration suppressed inhibin B secretion after 24 h, whereas short-term insulin suppression increased inhibin B. These findings suggest that both increased LH and insulin may account for the relative suppression of inhibin B in patients with PCOS.

Adolescent↗