Serum inhibin B levels in males with gonadal dysfunction

OBJECTIVE: To determine whether inhibin B levels are reflective of the etiology of gonadal dysfunction. DESIGN: Institutional study. SETTING: A tertiary care university-affiliated infertility clinic. PATIENT(S): Forty-four men: 16 with primary testicular failure, 10 with partial idiopathic hypogonadotropic hypogonadism (IHH), 8 with primary germ cell failure, one with iatrogenic hypogonadotropic hypogonadism, one with untreated Kallmann's syndrome, and 8 healthy fertile controls. INTERVENTION(S): Three individuals (one each with IHH, hypogonadotropic hypogonadism [HH], and Kallmann's syndrome) underwent treatment with human chorionic gonadotropin. MAIN OUTCOME MEASURE(S): Baseline serum inhibin B, FSH, LH, total testosterone and estradiol levels, and sperm concentrations were measured. RESULT(S): Serum inhibin B concentrations were significantly higher in fertile controls (255 +/- 59 pg/mL) than in men presenting with primary testicular failure (75 +/- 46 pg/mL, P<.0001) or in those presenting with primary germ cell failure (73 +/- 31 pg/mL, P<.0001). Inhibin B levels were also lower in males with partial IHH (187 +/- 112 pg/mL, P<.05). The patient with iatrogenic HH had a level of 184 pg/mL, whereas the patient with Kallmann's syndrome had nondetectable levels (<10 pg/mL). Serum inhibin B levels correlated positively with sperm concentration (P=.0001), and negatively with FSH levels (P=.01) and LH levels (P<.05). Human chorionic gonadotropin therapy altered inhibin B levels. CONCLUSION(S): Inhibin B plays an important role as an endocrine regulator of FSH secretion, whereas gonadotropins are involved in the regulation of inhibin B secretion.     

Antimüllerian hormone serum levels: a putative marker for ovarian aging

OBJECTIVE: To investigate whether serum concentrations of antimüllerian hormone may be used as a marker for ovarian aging. DESIGN: Longitudinal observational study. SETTING: Academic research center. PATIENTS: Forty-one normo-ovulatory premenopausal women and 13 healthy postmenopausal women. MAIN OUTCOME MEASURE(S): Concentrations of serum antimüllerian hormone (assessed on two occasions 2.6 +/- 1.7 years apart), FSH, inhibin B, and estradiol and number of ovarian follicles on ultrasonography. RESULT(S): Concentrations of antimüllerian hormone decreased significantly over time (median value, 2.1 microg/L [range, 0.1-7.4 microg/L] at visit 1 vs. 1.3 microg/L [range, 0.0-5.0 microg/L] at visit 2), whereas the number of antral follicles and levels of FSH and inhibin B did not change. During visits 1 and 2, concentrations of antimüllerian hormone correlated with age (r = -.40, P=.01 and r = -.57, P<.001, respectively); number of antral follicles (r =.66, P<.001 and r =.71, P<.001); and, to a lesser extent, with FSH level (r = -.29, P=.07 and r = -.37, P<.05) but not with inhibin B levels. CONCLUSION(S): Serum concentrations of antimüllerian hormone decreased over time in young normo-ovulatory women, whereas other markers associated with ovarian aging did not change. Concentrations of antimüllerian hormone correlate with the number of antral follicles and age and less strongly with FSH level. Concentrations of antimüllerian hormone may be a novel marker for ovarian aging.     

Concentrations of inhibins and activin in women undergoing stimulation with recombinant follicle-stimulating hormone for in vitro fertilization treatment

OBJECTIVE: To investigate the influence of human recombinant follicle-stimulating hormone (FSH) on circulating serum concentrations of the ovarian proteohormones inhibin A, inhibin B, pro alpha-C, and activin A and serum levels of estradiol after down-regulation with GnRH analogue. DESIGN: Serum concentrations of ovarian proteohormones and estradiol. SETTING: Academic clinical practice. PATIENT(S): 30 women who underwent assisted reproductive techniques. INTERVENTION(S): Blood samples were analyzed for inhibin A, inhibin B, pro alpha-C, activin A, and estradiol during IVF treatment at points coinciding with pituitary down-regulation, stimulation with recombinant FSH, ovulatory triggering, and the luteal phase of the cycle. RESULT(S): Activin A levels did not change with recombinant FSH stimulation. In women with a sonographically detected leading follicle >17 mm in diameter, levels of inhibin A, pro alpha-C, and estradiol increased significantly (P<.05). The increase in inhibin B level was not statistically significant. In patients without adequate follicle development during FSH stimulation, serum levels of inhibins remained low and did not significantly deviate from values measured before stimulation. CONCLUSION(S): Inhibin A and pro alpha-C are effective markers of follicular development and may be effective additions to estradiol as a marker.     

Inhibin A/B in HMG or recombinant FSH ovarian stimulation with cetrorelix medication

The inhibins are valuable factors in the assessment of the quality of an ovarian stimulation cycle. In spite of good clinical results with recombinant FSH and multiple dose LHRH- antagonist (Cetrotide((R))) administration, there remains a theoretical concern that in cycles stimulated with recombinant FSH, devoid of any LH activity, not enough endogenous LH is available to guarantee good follicle maturation. A total of 287 serum samples from 41 patients was assessed: 20 patients received ovarian stimulation with recombinant FSH, 21 patients with HMG and multiple dose Cetrotide administration. Inhibin A and B were measured on cycle days 2 and 6, the day of HCG administration, the day of embryo transfer as well as 7 and 14 days after the transfer. The two patient groups were similar with regard to age, amount of gonadotrophins required and number of follicles >18 mm and 15-18 mm. Inhibin A and B concentrations were comparable throughout the stimulation, thus indicating the equality of ovarian stimulation with recombinant FSH/HMG and midcyclic antagonist administration. Higher inhibin B concentrations throughout the stimulation were correlated with a higher oocyte yield. The small number of pregnancies prevented assessment of the relationship between inhibin B values and pregnancy rate.     

Inhibins in normal male physiology

Inhibin is a dimeric glycoprotein that suppresses follicle-stimulating hormone (FSH) secretion from the pituitary. Two bioactive forms of inhibin exist, inhibin A and B. The availability of specific immunoassays for each of the isoforms has enabled the study of the individual inhibins and their physiological roles. In the male, inhibin B is the circulating form in all species studied to date except the sheep. Inhibin B is produced in the testis, principally by the Sertoli cells. There are temporal changes in inhibin expression and secretion with the changing role of the Sertoli cell in immature and adult testes. Variations in inhibin B production between species reflect the different patterns of maturation. In the adult, inhibin B levels are positively correlated with Sertoli cell function, sperm number, and spermatogenic status and are negatively correlated with FSH. It appears that the regulation of inhibin B production is mediated by a complex interaction between FSH, Sertoli cells, Leydig cells, and germ cells. Inhibin may also play a role at an autocrine or paracrine level in modulating the actions of activin.     

Regulation and function of inhibins in the normal menstrual cycle

The development of assays specific for dimeric inhibin A and inhibin B defined the distinct physiology of these two hormones in the normal menstrual cycle. Inhibin A and inhibin B expression and secretion along with their differential regulation by gonadotropins explain their unique serum patterns and their potential endocrine and ovarian autocrine-paracrine functions. There is evidence that inhibin A and inhibin B play an endocrine role in the negative regulation of follicle-stimulating hormone (FSH) in nonhuman primates and humans. However, some studies suggest that estradiol is a more important, if not the only, negative feedback regulator of FSH in women. There is also evidence from animal models that inhibins and activins play a critical role in follicle development. Future work will be necessary to define further the relative role of the inhibins, estradiol, and other autocrine-paracrine factors in these important reproductive functions.     

The role of inhibin in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common heterogeneous disorder which, in its severest manifestations, is associated with anovulation, hyperandrogenism and metabolic imbalance. The biochemical markers for the condition can include a significantly raised LH:FSH ratio and a raised testosterone concentration, indicating a derangement of the hypothalamo--pituitary--ovarian axis which may be primary or secondary to a primary ovarian pathology. The bioactive inhibins are heterodimeric glycoproteins consisting of alpha-betaA (inhibin A) and alpha-betaB (inhibin B) subunits. They play an endocrine role in co-regulating (with oestradiol) the suppression of FSH during the late follicular and luteal phases of the ovarian cycle and they are implicated in intraovarian paracrine signalling. Inhibin B, which is the predominant form in small pre-ovulatory follicles, increases in concentration from early in the follicular phase to reach a peak coincident with the onset of the decrease in FSH which forms the basis of the pattern of mono-ovulation seen in normo-ovulatory women. Several unique features of the dysovulation of women with PCOS, namely their failure to recruit and develop a dominant follicle despite having 'normal' concentrations of endogenous FHS, the raised LH:FSH ratio and their exquisite sensitivity to exogenous FSH injections, may be explained by their significantly higher inhibin B concentrations. Studies into inhibin B parameters in women with PCOS demonstrate that women with anovular PCOS have significantly higher concentrations of circulating inhibin B and that they lack the pulsatile pattern of secretion that can be detected in normo-ovulatory women during the mid-follicular phase. The inhibin B response to ovulation induction with clomiphene citrate in women with PCOS differs from that in normo-ovulatory women taking the antioestrogen. Women with PCOS who over-respond to ovulation induction with injected FSH in a 'low-dose' step-up protocol' and recruit multiple follicles have significantly higher concentrations of pre-treatment inhibin B than PCOS subjects who do not.     

Luteal-phase inhibin A and follicular-phase inhibin B levels are not characteristic of patients with an elevated LH-to-FSH ratio

Purpose: To test whether serum inhibin levels are related to differences in gonadotropin concentrations between patients with an elevated LH-to-FSH ratio (ELF patients) and controls. Methods: 32 ELF patients were matched with controls by age, body mass index (BMI), and cycle length. Results: No statistically significant difference was found in follicular-phase inhibin B levels or midluteal inhibin A levels between cases and controls. Significant negative correlation was observed between follicular-phase inhibin B concentrations and BMI in ELF patients but not among controls. LH and FSH were positively related to inhibin B levels in ELF patients. Midluteal inhibin A correlated with sex hormone-binding globulin in controls but not in ELF patients. Conclusions: Neither follicular-phase inhibin B levels nor midluteal inhibin A levels are characteristic of patients with an elevated LH-to-FSH ratio. Opposite correlations with LH and BMI suggest dysregulation of inhibin secretion rather than dimeric inhibins having a central role to the endocrinological imbalance observed in polycystic ovary syndrome.Presented in part at the 18th Annual Meeting of the European Society for Human Reproduction and Embryology, Vienna, Austria, June 30 to July 3, 2002.     

The role of inhibin in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common heterogeneous disorder which, in its severest manifestations, is associated with anovulation, hyperandrogenism and metabolic imbalance. The biochemical markers for the condition can include a significantly raised LH:FSH ratio and a raised testosterone concentration, indicating a derangement of the hypothalamo-pituitary-ovarian axis which may be primary or secondary to a primary ovarian pathology. The bioactive inhibins are heterodimeric glycoproteins consisting of α-βA (inhibin A) and α-βB (inhibin B) subunits. They play an endocrine role in co-regulating (with oestradiol) the suppression of FSH during the late follicular and luteal phases of the ovarian cycle and they are implicated in intraovarian paracrine signalling. Inhibin B, which is the predominant form in small pre-ovulatory follicles, increases in concentration from early in the follicular phase to reach a peak coincident with the onset of the decrease in FSH which forms the basis of the pattern of mono-ovulation seen in normoovulatory women. Several unique features of the dysovulation of women with PCOS, namely their failure to recruit and develop a dominant follicle despite having ‘normal’ concentrations of endogenous FHS, the raised LH:FSH ratio and their exquisite sensitivity to exogenous FSH injections, may be explained by their significantly higher inhibin B concentrations. Studies into inhibin B parameters in women with PCOS demonstrate that women with anovular PCOS have significantly higher concentrations of circulating inhibin B and that they lack the pulsatile pattern of secretion that can be detected in normo-ovulatory women during the mid-follicular phase. The inhibin B response to ovulation induction with clomiphene citrate in women with PCOS differs from that in normo-ovulatory women taking the anti-oestrogen. Women with PCOS who over-respond to ovulation induction with injected FSH in a ‘low-dose’ step-up protocol’ and recruit multiple follicles have significantly higher concentrations of pre-treatment inhibin B than PCOS subjects who do not.     

Gonadotropic Control of Secretion of Dimeric Inhibins and Activin A by Human Granulosa–Luteal Cells In Vitro

Purpose: It is well established that human granulosa cells and luteal cells express inhibin/activin subunit protein and secrete immunoreactive inhibin. The gonadotropic control of secretion of different molecular forms of inhibin and activin A by granulose–luteal cells (G-LCs) was investigated using recently developed specific enzyme immunoassays (EIAs). Methods: Granulosa–luteal cells obtained at IVF egg pickup were cultured in a serum-free medium at 37°C in a water-saturated incubator with 5% CO ₂ for up to 5 days. Experiments with varying concentrations of human FSH, hLH, and hCG were carried out. Results: FSH raised the secretion of inhibin A and pro-C-containing inhibins after 24 and 48 hr in culture. Inhibin B was raised after 24 hr and activin A was raised after 48 hr of FSH treatment. LH treatment for 24 hr stimulated inhibin A, inhibin B, pro-C, and activin A. hCG stimulated G-LC secretion of inhibin A after 48 hr and pro-C after 24 hr. Paradoxically, inhibin B secretion was inhibited by 1 and 10 ng/ml hCG after 48 hr. Activin A was stimulated by hCG after 24 and 48 hr of incubation. G-LC secretion of estradiol and progesterone was also stimulated significantly by LH and hCG. Conclusions: Secretion of dimeric inhibins and activin A is controlled differentially by gonadotropins.     

Inhibins, activins and anti-Müllerian hormone: structure, signalling pathways, roles and predictive value in reproductive medicine

Anti-Müllerian hormone (AMH), inhibins and activins are members of the transforming growth factor (TGFbeta) superfamily and are known to have a variety of actions concerning reproduction, hormonogenesis, development processes and differentiation. Inhibins and activins are dimeric glycoproteins that are defined by their actions on the pituitary gonadotroph cells. AMH, inhibins and activins have a vast array of actions usually exerted through paracrine and endocrine mechanisms. The recent availability of specific inhibin assays has demonstrated that inhibin B is the relevant circulating inhibin form in the human male. Inhibin B seems to be a useful marker of spermatogenesis, but serum and seminal inhibin B levels are not predictive parameters for the selection of azoospermic men as candidates for testicular sperm extraction (TESE). AMH in seminal plasma may be important for sperm production, and is a good marker for sertoli cell development. It might be the only one seminal marker of spermatogenesis in non-obstructive azoospermia. Nevertheless, many of these studies were carried out with small patient numbers, and consequently must be interpreted with caution. In women ongoing assisted reproductive therapy (ART), day 3 inhibin B and AMH levels predict the number of oocytes retrieved, but cannot predict likelihood of pregnancy. Further studies are needed to determine if AMH and inhibin predict ART outcomes better than classical parameters (age, FSH levels and follicular ultrasonography). AMH and inhibin are also specific markers of Sertoli- and granulosa-cell origin in gonadal tumors.     

Inhibin A and B as markers of menopause: a five-year prospective longitudinal study of hormonal changes during the menopausal transition

OBJECTIVES: A more direct and precise hormonal marker of the menopause has been required for some time. The aim of this study was to identify the most accurate marker of the menopause, based on analyses of inhibin A and B, FSH, LH and estradiol (E(2)), among 59 healthy women without hormonal treatment during the perimenopause and early postmenopause. METHODS: Fifty-nine women, aged 46-56 years (mean age 51.2 years), were examined annually for 5 years during the menopausal transition and had venous blood drawn simultaneously for later analyses of the above-mentioned hormones. RESULTS: Inhibin A showed a steady decline from at least 4 years before the final menstrual period (FMP) until 1 year before menopause, whereas inhibin B had a shorter lasting decline from year 3 to year 2 before menopause, concomitant with a rise in FSH and LH. CONCLUSION: The present study confirmed previous observations that inhibin A had a continuous decline starting before the decline of inhibin B, suggesting that an increasing part of the cycle was anovulatory. The fall in inhibin B and the increase in FSH constitute markers of ovarian aging. One year prior to menopause neither inhibin A nor inhibin B could be detected. The disappearance of these peptide hormones is an important predictor of the approaching menopause.     

Inhibin B on the day of HCG-administration is a predictive factor for failure in assisted reproduction cycles

MATERIALS AND METHODS: This retrospective study was carried out in order to assess the value of inhibin B as a predictive factor for the assisted reproduction-outcome. Inhibin B on the day of HCG-administration (ovulation induction) was measured in 15 pregnant and 16 non-pregnant patients (defined as positive serum-HCG) and compared by single and multiple logistic regression analysis with classical predictive factors such as estrogen and oocyte number. Both groups were similar with respect to age and cause of infertility. RESULTS: While estrogen, FSH and LH at the HCG-day did not differ, inhibin B, the number of cumulus oocyte complexes and metaphase II -oocytes were statistically significantly different. In a single variable logistic model inhibin B, cumulus oocyte complexes and metaphase II oocytes showed significant correlation with pregnancy. When reassessed in a multiple variable logistic model only inhibin B maintained a considerable influence. Further inspection revealed, that the predictive inhibin B value at HCG-day <1200 pg/ml for failure of ART (assisted reproduction techniques) was 91%. Inhibin >1200 pg/ml showed 70% predictivity for pregnancy. CONCLUSION: In comparison to classical parameters inhibin B at HCG-day seems to be the better prognostic factor for the outcome of ART. Inhibin B <1200 pg/ml seems to be highly predictive for failure of ART.     

Follicular phase hormone levels and menstrual bleeding status in the approach to menopause

OBJECTIVE: (1) Characterize the relationship between follicular phase hormone levels and menstrual bleeding patterns in the approach to menopause; (2) identify racial differences in hormone levels; (3) determine independent contributions of menstrual status, race, age, BMI, and smoking to hormone levels. DESIGN: Randomly identified, population-based cohort, stratified to obtain equal numbers of African American and Caucasian women, prospectively followed for 5 years. SETTING: Women in Philadelphia County, PA, identified by random-digit telephone dialing. PARTICIPANT(S): Women aged 35 to 47 years with regular menstrual cycles at enrollment (N = 436). DATA COLLECTION: Blood sampling twice in each of 7 assessment periods during days 1-6 of the cycle, menstrual dates identified through structured interview and daily symptom reports, anthropometric measures and standardized questionnaires at each assessment period. MAIN OUTCOME MEASURE(S): Serum levels of follicular E(2), FSH, inhibin B, and LH. RESULT(S): The mean levels of E(2), FSH, inhibin B, and LH were differentially associated with the 5 menstrual status groups defined by changes in bleeding patterns. Significant changes in hormone levels occurred prior to missed menstrual cycles for inhibin B, FSH, and LH. All hormones had a highly significant interaction between menstrual status and BMI. African American women had significantly lower levels of E(2) and LH compared to Caucasian women in univariate analyses. The interaction of race, menstrual status, and BMI was highly significant (P<.001) for E(2), with African American women having lower E(2) levels until postmenopause, when E(2) levels were higher in AA women with BMI > or =25 and BMI > or =30. CONCLUSION(S): Levels of E(2), FSH, LH, and inhibin B are significantly associated with menstrual bleeding patterns in late reproductive age women and differentiate the earliest stages of the menopausal transition. Racial differences in mean levels of E(2) appear strongly mediated by BMI.     

Serum levels of inhibins are differentially altered in patients with polycystic ovary syndrome: effects of being overweight and relevance to hyperandrogenism

OBJECTIVE: To explore the abnormalities of serum inhibin isoform concentrations in a large group of patients with polycystic ovary syndrome (PCOS) and to evaluate the influence of body mass index (BMI), age, LH, and androgens on serum inhibin levels. DESIGN: Prospective study. SETTING: Reproductive endocrinology unit of an academic medical center. PATIENT(s): Forty-one women with PCOS were compared with 24 healthy women. INTERVENTION(s): Blood sampling was performed in the early follicular phase in patients and in control women. MAIN OUTCOME MEASURE(s): Serum levels of inhibin A, inhibin B, alpha-inhibin, pro-alphaC (alpha-inhibin precursor proteins), LH, FSH, E(2), T, and androstenedione (A) were assessed in all subjects. RESULT(s): Serum alpha-inhibin levels together with LH, T, and A levels were significantly increased in women with PCOS. Serum inhibin A levels were lower in patients with PCOS than controls (median +/- SD: 7.35 +/- 2.9 vs. 9.4 +/- 4.7 pg/mL), pro-alphaC levels were higher (264 +/- 136.7 vs. 127 +/- 81.5 pg/mL), and inhibin B levels did not differ between the groups (110.5 +/- 51.5 vs. 108 +/- 47.5 pg/mL). Simple regression analysis showed that inhibin A and B levels were negatively correlated with BMI in patients with PCOS (r = -0.43 and r27 kg/m(2)) displayed significantly lower inhibin A and inhibin B levels and a higher pro-alphaC-inhibin A ratio than nonobese patients with PCOS (BMI 相似文献   

Analysis of follicular fluid hormone concentrations and granulosa cell mRNA levels for the inhibin-activin-follistatin system: relation to oocyte and embryo characteristics

OBJECTIVE: To explore the potential roles of inhibin, activin, and follistatin in human oocyte development by quantifying their intrafollicular biosynthesis. DESIGN: Prospective, nonrandomized study. SETTING: An IVF unit and academic research laboratory. PATIENT(S): Thirty one patients undergoing IVF. INTERVENTION(S): Human menopausal gonadotropins or human FSH (or both) were administered. Single-follicle aspirates (n = 110) were collected for analysis. MAIN OUTCOME MEASURE(S): Concentrations of dimeric, total and pro-alphaC inhibin forms; activin A; follistatin; estradiol; and progesterone were measured in follicular fluids. Granulosa-cell mRNA was analyzed for alpha, beta A, and beta B inhibin and activin subunits; follistatin; activin receptors; and beta-actin. Hormone concentrations and mRNA levels were correlated with oocytes or embryos from the same follicles. RESULT(S): Levels of progesterone and follistatin were significantly greater in follicles containing MI or MII oocytes than in those containing GV oocytes. Inhibin alpha-subunit mRNA levels were significantly higher in follicles containing maturing oocytes, the highest-quality oocytes, and oocytes that were subsequently fertilized. In contrast, inhibin alpha-subunit mRNA levels were significantly lower in follicles from which higher-quality embryos were obtained. CONCLUSION(S): Inhibin alpha-subunit biosynthesis is associated with normal oocyte and follicle maturation, but excessive alpha-inhibin is associated with poor embryo quality. None of the hormones analyzed were associated with oocyte or embryo quality.     

Diagnostic role of inhibin B in resistant ovary syndrome associated with secondary amenorrhea

To report two rare cases of gonadotropin-resistant ovary syndrome associated with secondary amenorrhea and normal levels of inhibin B.Case report.Two university teaching hospitals.Two women presenting with secondary amenorrhea and infertility. The control group for the inhibin B levels consisted of 30 cycling women of reproductive age.Medical history, physical examination, laboratory data, histologic findings, and IVF results.Diagnosis and treatment of resistant ovary syndrome.Case 1 was a 25-year-old woman with secondary amenorrhea and primary infertility. She had high serum levels of FSH and LH, low E(2) levels, and normal inhibin B levels (62 pg/mL). Karyotype was 46,XX, and ovarian biopsy showed primordial follicles with oocytes. Administration of GnRH analogue with hMG for 15 days did not affect E(2) levels. She had a successful pregnancy with IVF using donor oocytes. Case 2 was a 24-year-old woman with secondary amenorrhea. She had elevated serum levels of FSH and LH, low E(2) levels, and normal inhibin B levels (57 pg/mL). Karyotype was 46,XX and ovarian biopsy showed primordial follicles. Administration of GnRH analogue with hMG for 12 days did not affect E(2) levels. Both women were given estrogen-progestin replacement therapy.Inhibin B has a diagnostic role in women with gonadotropin-resistant ovary syndrome associated with secondary amenorrhea. A review of the literature confirms the uniqueness of the diagnostic role of inhibin B in these cases.     

Use of serum inhibin B levels at the start of ovarian stimulation and at oocyte pickup in the prediction of assisted reproduction treatment outcome

OBJECTIVE: To assess whether serum inhibin B levels before gonadotropin administration and at oocyte pickup (OPU) are associated with pregnancy. DESIGN: Retrospective case-control study. SETTING: University-based IVF program. PATIENT(S): Fifty-five IVF pregnancies and 55 control cycles matched by age, type of infertility, E(2) at ovulation induction, number of oocytes retrieved, and number of embryos replaced. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Association between serum inhibin B at stimulation day 1 (SD1) and OPU and pregnancy; correlation between inhibin B with clinical and endocrine parameters; predictive accuracy of inhibin B measurements at OPU. RESULT(S): Inhibin B on SD1 was similar between pregnant and nonpregnant subjects, whereas it was significantly higher at OPU in pregnant cycles, but did not allow differentiation between pregnancy outcomes. Inhibin B on SD1 was positively correlated with same-day E(2) in both groups and inversely with age in pregnant cycles. In both groups, inhibin B at OPU correlated positively with number of oocytes collected and with E(2) at ovulation induction. CONCLUSION(S): Higher inhibin B concentrations at OPU are predictive of clinical pregnancy, independently of age, peak E(2), number of oocytes retrieved and number of embryos replaced. Inhibin B on stimulation day 1 did not prove to be a useful predictor.     

Inhibins as biomarkers for reproductive cancers

Inhibin is a dimeric (alpha and either betaA or betaB subunit) protein involved in the regulation of fertility. Inhibin A and B or its free alpha subunit monomer are elevated in various gonadal and prostate cancers and thus serve as useful diagnostic tools for certain ovarian tumors either as a serum marker or as an immunocytochemical marker for tissue sections. Serum inhibin levels are of value in the initial diagnosis and subsequent follow-up of sex cord stromal tumors, in particular granulosa cell tumors, and mucinous epithelial adenocarcinomas primarily after menopause. Immunocytochemistry using inhibin alpha subunit antisera can aid in the classification of sex cord stromal tumors and their differentiation from other cancers. Although serum inhibins are elevated in prostatic and testicular cancers, this is of little diagnostic value at the present time.     

Inhibin B--a marker of the function of male gonad

Inhibin B is one of the growth factors mediating between Sertoli cells and germ cells. Inhibin B plays a role in the negative feedback control of FSH secretion in men. Inhibin B levels are low in the first week after birth in male newborns, then increase up to the 6th month of age and then decline progressively to reach their nadir towards 3-6 years. They become high again during puberty. Studies about influence of inhibin B on concentration and spermatogenic activity confirmed, that inhibin B can be used as a marker to estimate the Sertoli cells function. It has been proven that serum inhibin B levels in adult men correlate positively with sperm concentration. Inhibin B secretion decreases with men age what can be connected with FSH serum level increase. Inhibin B can be also used to diagnose and monitor many disturbances of spermatogenesis like different etiology azoospermia, primary testicular failure, hypogonadotropic hypogonadism, Kallman's syndrome, Klinefelter's syndrome, cryptorchidism, precocious puberty and complete or selective loss of subthalamus or pituitary function. Inhibin B is also considered as a good marker of spermatogenesis in population researches (especially together with FSH serum levels).