Serum inhibin as an index of ovarian function in women undergoing pituitary suppression and ovarian stimulation in an in vitro fertilization program

Inhibin B levels on cycle day 3 to predict the ovulatory response in women with PCOS undergoing ovulation induction via low dose step-up gonadotropin protocol

BACKGROUND

In this prospective clinical single blind study, we aimed to investigate whether day 3 serum inhibin B levels in women with polycystic ovarian syndrome(PCOS) are of predictive value for the estimation of the ovarian response to gonadotropins.

METHODS

Ovulation induction with low dose step-up gonadotropin protocol, starting with 75 IU/day, was performed for 30 cycles on 25 patients with PCOS. Day 3 serum inhibin B, follicle-stimulating hormone(FSH) and estradiol, and midluteal serum progesterone levels were measured during each cycle. The correlations between day 3 inhibin B levels and day 3 FSH, day 3 estradiol and midluteal progesterone measurements, as well as the amount of gonadotropin required to provide an ovulatory cycle were investigated.

RESULTS

Five (27.8%) out of 18 cycles with day 3 inhibin levels <50.0 pg/ml; and 11 (91.7%) out of 12 cycles with levels > or = 50.0 pg/ml were ovulatory (chi(2)=9.38, p<0.01). Moreover, day 3 inhibin B levels had statistically significant negative correlation with the gonadotropin used; and significant positive correlation with the midluteal progesterone levels (p<0.05). There wasn't any significant relation between day 3 FSH and estradiol levels with the gonadotropin used and progesterone levels.

CONCLUSIONS

It has been observed that as day 3 serum inhibin B levels increased in women with PCOS, the ovulatory response to gonadotropins and the rate of ovulatory cycles increased significantly.

Day 5 inhibin B levels in a treatment cycle are predictive of IVF outcome

BACKGROUND

Day 5 serum inhibin B during IVF treatment has been investigated as a predictor of outcome.

METHODS

A total of 54 women (< or = 39 years, normal menses and endocrine profiles) were treated with urinary gonadotrophins or recombinant FSH following pituitary down-regulation. Serum day 3 FSH in a preceding cycle was <8.5 IU/l. Plasma inhibin B, inhibin A and estradiol were determined after 4 days of gonadotrophin administration (day 5).

RESULTS

Day 5 inhibin B was the most highly correlated with the number of mature follicles (>14 mm), oocytes retrieved and fertilized. Receiver operating characteristic analysis gave high accuracy for day 5 inhibin B in predicting ovarian response and indicated that a threshold of 400 pg/ml may be helpful in the decision as to whether to continue treatment. Women with <400 pg/ml (n = 16) had lower numbers of follicles, mature follicles, oocytes retrieved, fertilized and cleaved compared with those >400 pg/ml (n = 36) and this threshold gave a positive likelihood ratio of 30, 92.9% sensitivity, 95.0% specificity and 86.7% positive predictive value to detect poor ovarian response. Day 5 inhibin B was the best predictor of pregnancy (no live births and four cycles cancelled, low inhibin group; nine live births and no cancelled cycles, high inhibin group).

CONCLUSIONS

Normogonadotrophic, normogonadal women with day 5 inhibin B <400 pg/ml in down-regulated cycles have a poor response to ovarian stimulation and are less likely to conceive compared with women with higher day 5 inhibin B.

Basal and day 12 inhibin concentrations in the prediction of ovarian response to gonadotrophins in women with PCOS

BACKGROUND

In this study, we aimed to investigate whether basal and day 12 serum total inhibin concentrations in women with polycystic ovarian syndrome (PCOS) were of predictive value for the estimation of the ovarian response to gonadotrophins.

METHODS

Ovulation induction with a very low dose gonadotrophin protocol, starting with 37.5 IU/day, was performed for 40 cycles on 35 patients with PCOS. Day 3 (basal) serum total inhibin, FSH and oestradiol concentrations; day 12 dominant follicle diameter, inhibin and oestradiol concentrations and midluteal serum progesterone concentrations were measured during the 40 cycles. The correlations between basal and day 12 inhibin concentrations and some critical ovulation monitoring parameters were investigated.

RESULTS

Ovulation was obtained in 14 out of 40 cycles: 21% of cycles with basal inhibin <1.0 IU/ml; 33.3% of cycles with basal inhibin between 1.0-1.9 IU/ml; and 83.3% of those with inhibin concentrations > or =2 IU/ml were ovulatory (P < 0.05). Ovulation was achieved in 91.6% of the cycles with a day 12 inhibin concentration > or =4 IU/ml.

CONCLUSIONS

Basal inhibin concentrations may determine poor and good responders to ovulation induction with very low dose gonadotrophin protocol in patients with PCOS. The day 12 inhibin concentration was found to be a more sensitive parameter than the oestradiol concentration in the prediction of follicular maturation.

Inhibin A and inhibin B reflect ovarian function in assisted reproduction but are less useful at predicting outcome

To test the hypothesis that dimeric inhibin A and/or inhibin B concentrations represent improved markers of in-vitro fertilization (IVF) outcome over follicle stimulating hormone (FSH), 78 women who achieved pregnancy within three assisted reproduction treatment cycles were matched to 78 women who underwent at least three assisted reproductive treatment cycles and failed to achieve pregnancy. Baseline serum inhibin B and FSH were obtained between days 1 and 4 in a cycle prior to ovarian stimulation, and inhibin A and B were measured immediately before the ovulatory stimulus and in follicular fluid from the lead follicle. Comparing pregnant and non-pregnant subjects at baseline, younger age (34.0 +/- 0.5 versus 36.0 +/- 0.5 years; P < 0.003) and a combination of FSH lower than the median value (11.2 IU/l) and inhibin B higher than the median value (76.5 pg/ml) were associated with pregnancy (P < 0.03), but FSH (11.7 +/- 0.5 versus 12.9 +/- 0.9 IU/ml) and inhibin B (89.0 +/- 10.2 versus 79.7 +/- 7.7 pg/ml) were not independently associated. At the time of the ovulatory stimulus, serum inhibin A (52.8 +/- 3.8 versus 40.0 +/- 2.7 IU/ml; P < 0.004), inhibin B (1623.8 +/- 165.1 versus 859.2 +/- 94.8 pg/ml; P < 0.0009) and the number of oocytes retrieved (14.6 +/- 0.8 versus 10.1 +/- 0.6; P < 0.0001) were predictive of pregnancy when controlled for age. Inhibin A was correlated with the number of embryos (r = 0.4; P < 0.0001). However, neither inhibin A nor inhibin B provided additional information in predicting successful outcome over age and number of oocytes. We conclude that: (i) in patients undergoing assisted reproductive technology, age and number of oocytes retrieved are the strongest predictors of success; (ii) of the parameters available prior to cycle initiation, a combination of lower FSH and higher inhibin B was associated with a greater chance for a successful outcome but an absolute cut-off could not be defined; and (iii) during ovarian stimulation, higher concentrations of inhibin A and inhibin B in serum are associated with successful IVF and mark ovarian reserve as a measure of oocyte number and quality.

Immunoreactive inhibin concentration in blood tested under variable sampling conditions

The stability of immunoreactive (i.r.) inhibin in blood samples drawn and handled under different conditions and at different time intervals were studied. Ten serum and plasma samples drawn in 1994 from healthy volunteers were compared to samples collected in 1986 from 10 healthy women admitted for laparoscopic sterilization and analysed 6 years later. All samples were drawn on the twelfth day of the menstrual cycle and handled under identical clinical conditions (22 degrees C). The concentrations in the 1986 samples were similar to the Se-i.r. inhibin levels from 1994. Different clotting temperatures, repetitive freezing and thawing or hemolysis had no effects on the i.r. inhibin values, whereas non-hemolysed samples left at room temperature (22 degrees C) for 3 days were significantly lower, which might be due to a statistical type 2 error. No differences in concentration between serum and plasma i.r. inhibin were demonstrated. In conclusion, i.r. inhibin is a very stable peptide hormone in both serum and plasma if drawn and handled under normal conditions.

Immunoreactive inhibin-production in post-menopausal women with malignant epithelial ovarian tumors

In post-menopausal women with a malignant epithelial ovarian tumor the follicle stimulating hormone (FSH) level was found to be significantly lower compared with healthy controls. We demonstrated immunoreactive (i.r.) inhibin in 20% of controls which was elevated to 60% of women with an ovarian tumor and correlating strongly to FSH in the tumor group (P = 0.0002). Steroid hormone levels were comparable in the two groups. In women with ovarian tumors the survival time for the i.r. inhibin-producing women was found to be 4.6 years compared with 0.9 year, or 5.1 times longer than in the non-producing women (P = 0.002). The site of i.r. inhibin production in these post-menopausal women is unknown, but i.r. inhibin production by the developing ovarian tumor or by the post-menopausal ovary may be regarded as a defense mechanism against an elevated gonadotrophin level (the gonadotrophin theory) which would promote further tumor growth. The recent suggestion that the alpha subunit of inhibin is a tumor suppressor gene is consistent with these results. The serum i.r. inhibin or alpha subunit concentrations might be used as an aid to diagnosis or as a prognostic indicator of survival in women with an ovarian carcinoma.

Elevated serum immunoreactive inhibin levels in peripubertal boys with chronic renal failure. Cooperative Study Group on Pubertal Development in Chronic Renal Failure (CSPCRF)

OBJECTIVE

Boys with chronic renal failure have delayed progress through puberty and have raised gonadotrophin and low testosterone levels indicative of disturbed hypothalamo-pituitary-testicular function. Most studies into the mechanisms underlying the dysfunction have concentrated on the LH-Leydig cell interaction. However, it is now possible to probe the FSH-Sertoli cell axis by measuring plasma immunoreactive inhibin, which is a marker of Sertoli cell function. This study investigated the FSH-Sertoli cell (immunoreactive inhibin) axis in boys with chronic renal failure on conservative and dialysis treatment as they progressed through puberty. The effect of renal transplantation in chronic renal failure was also investigated.

DESIGN

Blood was drawn at 15-minute intervals between 2000 and 0700 h from 51 boys with chronic renal failure at various stages of puberty. The samples were divided into two pools, corresponding to the hormone secretion in the first and second part of the night. Single blood samples were drawn from a group of normal boys between 0800 and 1000 h.

PATIENTS

A total of 37 normal boys and 51 boys with chronic renal failure were examined immediately before and during puberty. Of a total of 80 pulse profiles taken in chronic renal failure, 36 were from transplanted and 44 from non-transplanted uraemic subjects.

MEASUREMENTS

Immunoreactive inhibin, FSH and testosterone were measured using standard radioimmunoassays. The subjects were pooled into pubertal stages I, II/III and IV/V for analysis of hormone data.

RESULTS

Early morning levels of immunoreactive inhibin like molecules (i-Inh) rose steadily with pubertal progression for all subject groups, those for boys with chronic renal failure being significantly elevated over normal boys from pubertal stage II/III onwards. Uraemic boys had higher levels than those who had been transplanted at all pubertal stages (P < 0.05). Early morning levels of FSH were significantly higher in uraemic patients with pubertal stages IV/V compared to our normal boys. There were no differences in i-Inh levels in plasma pooled from the samples taken between 2000 and 0115 h and 0130 and 0700 h for either treatment group at any stage of puberty. Testosterone levels rose in the second part of the profile from pubertal stages II/III onwards for both treatment groups. The proportional increase of testosterone was lower by mid puberty in uraemic than in transplanted children (percentage increases of 92 +/- 29 and 569 +/- 190 respectively, mean +/- SEM). i-Inh failed to correlate with FSH at any Tanner stage or for any subject group.

CONCLUSION

Peripubertal boys with chronic renal failure have highly elevated serum immunoreactive inhibin and FSH levels which are partially reduced by renal transplantation. There was no evidence of any relationship between i-Inh and FSH secretion in either normal boys or in uraemic or transplanted boys with the exception of a positive correlation in late pubertal patients after transplantation. Finally, despite problems associated with the current immunoassay for inhibin, this assay may still prove to be a useful marker of Sertoli cell function in testicular pathology.

Immunoreactive inhibin levels during ovarian stimulation may predict granulosa cell maturity

OBJECTIVE

The aim of the study was to assess whether the immunoreactive inhibin response to ovarian stimulation in polycystic ovarian syndrome was of predictive value for the outcome of ovulation induction.

DESIGN

Daily injections of purified FSH (Metrodin, Serono Laboratories, UK) were administered for the purpose of inducing development and ovulation of a single follicle.

PATIENTS

All patients had anovulatory infertility secondary to polycystic ovarian syndrome and were resistant to clomiphene citrate.

MEASUREMENTS

Alternate day serum samples were obtained for measurement of gonadotrophins, sex steroids and inhibin by radioimmunoassay. Alternate day ovarian ultrasound scans were carried out to monitor follicular development.

RESULTS

There was a high incidence of multiple follicular development (MFD) (10.2 +/- 7.1 (standard deviation) follicles). There was a close relationship between the number of follicles on the day of the ovulatory trigger and serum oestradiol (E2) levels (R = 0.97, P < 0.001). This relationship was not seen with serum immunoreactive inhibin levels (R = 0.31). The cycles were divided into two groups depending whether there was or was not MFD (more than five follicles > 7 mm in diameter on day of hCG administration). The MFD group had 15.6 +/- 8.5 follicles and the non-MFD group 3.2 +/- 1.6 follicles. There was no difference in the circulating E2 concentration (pmol/l) per follicle between the two groups (non-MFD cycles, n = 6,345 +/- 28.9; MFD cycles, n = 8, 308 +/- 40.29). However, the immunoreactive inhibin concentration (U/ml) per follicle was lower, P < 0.001, in the MFD group (4.3 +/- 1.6 vs 6.9 +/- 0.5). The maximum and mean follicle diameter were lower, P < 0.01, in the MFD group (maximum follicle size 16.5 +/- 3.9 vs 21.2 +/- 1.5 mm, mean follicle size 11.5 +/- 2 vs 14.9 +/- 2.3). When individual cycles were examined E2 and immunoreactive inhibin secretion rose in parallel in cycles with less than five follicles with a rapid rise occurring when the follicles reached about 12 mm in diameter. In cycles where there was MFD there was a disparity between E2 and immunoreactive inhibin secretion with E2 levels rising 4.3 +/- 1.4 days before immunoreactive inhibin levels.

CONCLUSION

These data suggest that in cycles where there are multiple small follicles, E2 secretion is maintained whereas immunoreactive inhibin secretion is substantially lower. Thus, in view of the disparity between E2 and immunoreactive inhibin secretion evident in the MFD group, measurement of immunoreactive serum inhibin concentration may be a better indicator of granulosa cell maturity. Immunoreactive inhibin secretion may occur only from healthy mature follicles.