Peripheral blood concentrations of inhibin B are elevated during gonadotrophin stimulation in patients who later develop ovarian OHSS and inhibin A concentrations are elevated after OHSS onset

A. Enskog1, L. Nilsson and M. Brännström

Department of Obstetrics and Gynaecology, Göteborg University, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden


    Abstract
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 Abstract
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 Materials and methods
 Results
 Discussion
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Ovarian hyperstimulation syndrome (OHSS) is a serious side-effect of controlled ovarian stimulation. Inhibin A and inhibin B, as putative predictors of OHSS development in the same stimulation cycle, were evaluated. A cohort of 428 in-vitro fertilization (IVF) patients was followed. Fifteen patients with severe OHSS were compared with matched (age, follicle number) controls. Serum samples were obtained at five time points from the start of ovarian stimulation until >= 3 days post-embryo transfer and analysed with specific enzyme-linked immunosorbent assays. Inhibin A in the OHSS group showed a continuous increase with a significant elevation 3 days prior to oocyte aspiration (ASP-3) and onwards. Maximal concentrations were detected at embryo transfer and the concentrations remained high at >= 3 days post-embryo transfer. Inhibin A concentrations in the control group showed a transient elevation (significant increase at ASP and embryo transfer). Inhibin A in the OHSS group was significantly higher than in controls only at the time point where OHSS had developed (>= 3 days post-embryo transfer), and declined during OHSS treatment. Overall, there was a positive correlation between the number of follicles and inhibin A concentrations at ASP-3 until embryo transfer in the control group but not in the OHSS group. The concentrations of inhibin B in both groups increased from the start of ovarian stimulation, with peak values at ASP-3, and then a decline. Inhibin B was significantly higher in OHSS patients at ASP-3 and at ASP. Inhibin B at ASP-3 was correlated with the total number of follicles in both the OHSS group and the control group.

Key words: inhibin A/inhibin B/IVF/ovarian hyperstimulation syndrome


    Introduction
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 Abstract
 Introduction
 Materials and methods
 Results
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 References
 
The ovarian hyperstimulation syndrome (OHSS) is a serious side-effect of ovarian stimulation and incidences of severe OHSS varying between 0.3 and 5% have been reported (Navot et al., 1995Go). These fairly large differences in the incidence reported are most likely due to disparities in stimulation protocols or patient selection, but may also depend on differences in the ability to predict OHSS risk. The risk assessment is usually based on a combination of background data and various clinical parameters obtained during the ongoing stimulation. A supposed high risk for OHSS development may then initiate a number of clinical modifications, such as administration of lower gonadotrophin dose (Hamilton-Fairley et al., 1991Go), shift from human chorionic gonadotrophin (HCG) to progesterone as luteal support (Araujo et al., 1994Go), prolonged coasting (Sher et al., 1995Go), freezing of all embryos (Bergh et al., 1995Go) or cancellation of HCG (Navot et al., 1992Go) to decrease the risk of OHSS.

Concerning background factors, it has been said that OHSS is more prevalent in younger patients (Delvigne et al., 1993Go), in patients with polycystic ovarian syndrome (PCOS; Navot et al., 1988), in patients with manifest allergy (Enskog et al., 1999Go), and possibly also in patients of lower weight (Navot et al., 1988Go). Concerning factors appearing during stimulation, development of a great number of follicles (Blankstein et al., 1987Go), especially of larger sizes (Enskog et al., 1999Go) during ovarian stimulation may be related to the risk of OHSS development in the same stimulation cycle. Oestradiol, of which >95% is produced by the dominant follicle during the natural cycle (Baird and Fraser, 1975Go), is the only endocrine parameter which has been claimed to be helpful in predicting OHSS (Navot et al., 1988Go). However, recent studies have questioned the utility of plasma oestradiol measurements in predicting OHSS (Morris et al., 1995Go; Delvigne et al., 1997Go), and the value of oestradiol measurements in this context may be even less with the use of recombinant FSH, since the amount of oestradiol produced per follicle has been claimed to be reduced (Devroy et al., 1994) in this situation. Several other circulating factors such as cytokines (Loret de Mola et al., 1996Go) and permeability enhancing factors (Abramov et al., 1997Go), which mostly act as paracrine mediators, have been evaluated as potential OHSS predictors but the blood concentrations of these classes of substances do not seem to rise before the onset of OHSS.

Inhibins are produced by the ovary and their main functions are to regulate follicle stimulating hormone (FSH) secretion from the pituitary by endocrine mechanisms and to regulate ovarian steroidogenesis by autocrine/paracrine mechanisms (Baird and Smith, 1993Go). Inhibins are heterodimers, consisting of disulphide-linked {alpha} and ß subunits. Inhibin A consists of the {alpha}-subunit and the A-type of the ß-subunit, while inhibin B consists of the {alpha}-subunit and the B-type of the ß-subunit. The amino acid sequences of the ß-subunits show 70% homology and there is ~30% homology between the sequences for the {alpha}- and ß-subunits. All the three subunit components of inhibin A and inhibin B have been demonstrated to be expressed in both theca and granulosa cells of the follicle when assessed both as the protein (Yamoto et al., 1992Go) and mRNA (Burns et al., 1990Go; Erämaa et al., 1993Go). Measurements of inhibin concentrations in peripheral blood of women of reproductive age have revealed that the concentrations of inhibin B increase during the early follicular phase to a peak on the day after the intercycle FSH peak and with a second shorter but more pronounced peak 2 days after the mid-cycle gonadotrophin peak, followed by declining concentrations throughout the luteal phase (Groome et al., 1996Go; Schipper et al., 1998Go). The pattern of inhibin A concentrations in the circulation is different, with low concentrations during the early follicular phase and a modest peak on the day of the LH peak, followed by a brief decrease and then a rise to maximal concentrations during the mid-luteal phase (Groome et al., 1996Go; Schipper et al., 1998Go). Thus, inhibin B can be considered as mostly a follicular phase hormone with a role in inhibition of FSH secretion during this phase, while inhibin A is mostly a luteal phase hormone. During pituitary desensitization with gonadotrophin-releasing hormone (GnRH), there is marked suppression of inhibin concentrations with large elevations of these hormones during gonadotrophin stimulation (Lockwood et al., 1996Go). In addition, inhibin concentrations during basal conditions and during ovarian stimulation may be related to in-vitro fertilization (IVF) outcome (Hall et al., 1999Go). Taken together, both inhibin A and inhibin B concentrations seem to be related to the extent of follicular selection and both could thus be useful marker hormones for predicting and monitoring OHSS. The aim of the present study was to compare inhibin A and B concentrations in peripheral blood of patients who developed severe OHSS with that of their matched controls out of a large cohort of IVF patients treated in one centre.


    Materials and methods
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 Introduction
 Materials and methods
 Results
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The study was approved by the Human Research Ethics Committee at the Faculty of Medicine, Göteborg University and by the federal Data Inspection Board.

Patients
All patients (428) undergoing ovarian stimulation for IVF at the Reproductive Medicine Unit, Department of Obstetrics and Gynaecology, Sahlgrenska University Hospital during a 6-month period were followed. The OHSS patients were classified in accordance to established criteria (Golan et al., 1989Go) but with the modification that severe abdominal pain necessitating hospitalization was categorized as severe OHSS regardless of clinically diagnosed ascites. Other diagnoses were excluded on the basis of clinical development; ultrasound and HCG concentration were used to exclude ectopic pregnancy, C reactive protein was used to exclude pelvic inflammatory disease and haemorrhagic follicular cysts were excluded as causes of severe abdominal pain. A detailed description of the entire study population and their background data as well as routine clinical findings has recently been published (Enskog et al., 1999Go).

In the present study, 15 patients who developed severe OHSS were compared with 30 IVF patients who did not develop OHSS. These control patients were matched for age, numbers of follicles and pregnancy rate (Table IGo) but not for luteal support. However, progesterone was probably more prevalent in the OHSS group, as this was used as a corrective measure when OHSS was suspected (see below). In the analysis of the OHSS and control groups, it was also evident that no difference existed in the number of large follicles, oestradiol values, and prevalence of allergy (Table IGo).


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Table I. Characteristics (expressed as mean±SEM or %) of ovarian hyperstimulation syndrome (OHSS) cases and controls
 
It should be noted that since several factors previously have been linked to the susceptibility to develop OHSS (Navot et al., 1988Go), the general clinical routine in our and most other IVF centres is prior to or during stimulation, to attempt to define risk groups for OHSS and to modify their treatment. Factors indicative of polycystic ovary (PCO) and factors indicative of high follicle reserve in relation to body mass were considered risk factors, which were identified prior to treatment. The clinical factors which were PCO-indicative were: amenorrhoea/oligomenorrhoea or menstrual interval >32 days, marked menstrual irregularity, PCO sign [>10 peripherally situated follicles of >5 mm/ovary in one projection on transvaginal ultrasound examination (TVS)], and hirsutism/acne. The clinical factors which were indicative of high follicle reserve were: age <30 years, weight <48 kg and >10 follicles/ovary under basal conditions. The presence of any of these factors resulted in treatment with GnRH agonist for a longer time, a lower starting dose of FSH/human menopausal gonadotrophin (HMG) and in addition progesterone as luteal support. We were aware that these adjustments could have biased the outcome (OHSS or not) if they are effective. However, these were clinical adjustments, which probably exist in all studies on OHSS.

Stimulation and monitoring
Patients were down-regulated by 0.9–1.2 mg/day of intranasal buserelin acetate (Suprefact; Hoechst AB, Frankfurt am Main, Germany) and ovarian stimulation was commenced when oestradiol concentrations in serum were <0.25 nmol/l. Any ovarian cyst of size >15 mm was punctured under TVS monitoring before the start of ovarian stimulation.

The stimulation protocol utilized 75–225 IU/day of FSH (Metrodin or Metrodin-HP; Serono, Rome, Italy) alone (7/15 in OHSS, 10/30 in controls) or in combination (8/15 in OHSS, 20/30 in controls) with HMG (Pergonal, Serono, Rome, Italy; Humegon, Organon, Oss, The Netherlands). Serum oestradiol concentrations were monitored with 1–3 day intervals during ovarian stimulation, and at least one TVS examination of the ovaries was performed each week. The dose of FSH/HMG was adjusted to the rise in oestradiol and the TVS findings. HCG (5–10 000 IU; Profasi®, Serono or Pregnyl®, Organon) was given when at least three follicles attained a diameter of 18–20 mm, and follicular aspiration (ASP) was performed 34–38 h later by TVS. Routinely, luteal support was provided by HCG (2500 IU) given s.c. at oocyte aspiration (ASP) and embryo transfer, followed by 1250 IU HCG given four times with 3-day intervals. When risk of OHSS was suspected, progesterone (50 mg i.m.) was given instead of HCG.

Hormone assays
Inhibin A and inhibin B were measured using specific enzyme-linked immunosorbent assay (ELISA) kits (Serotec Ltd, Oxford, UK) according to the manufacturer's protocols. The assays are based on previously published methods for measuring inhibin A (Groome et al., 1994Go) and inhibin B (Groome et al., 1996Go). Serum oestradiol concentrations were measured with a commercial kit (Abbott IMx; Abbott Park, IL, USA; sensitivity limit 0.09 nmol/l). The inter- and intra-assay variations were <10% for all assays.

Data collection and statistics
Blood samples were taken at the start of gonadotrophin stimulation (G-ST) and at subsequent visits to the clinic during and after stimulation. The concentrations of inhibin A and B in the OHSS group and the control group were compared at G-ST, 3 days prior to follicular ASP (ASP-3), day of aspiration (ASP), day of embryo transfer, and at a time >3 days after embryo transfer. In the OHSS patients, serum samples were also drawn on the day of discharge from the hospital (DIS). The longitudinal variations within each group were analysed by analysis of variance (ANOVA) and by Scheffé's post hoc test for individual comparisons. For each time point, the difference between control and OHSS groups was assessed with unpaired Student's t-test. The data are expressed as means ± SEM. Correlation was tested with Pearson's test. A P-value <=0.05 was considered statistically significant for all comparisons.


    Results
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 Materials and methods
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Inhibin A concentrations
The concentrations of inhibin A were low (<5 pg/ml) on the starting day of ovarian stimulation (G-ST; Figure 1Go). The concentrations increased to >100-fold higher concentrations at ASP-3 and then increased slowly up to embryo transfer, where they reached maximal concentrations in both groups (1198 ± 146 and 908 ± 85 pg/ml in the OHSS group and the control group respectively). At the subsequent time point (>=3 days post-embryo transfer) the concentrations remained high in the OHSS group (1118 ± 139 pg/ml) but showed a decrease in the control group (473 ± 141 pg/ml). The concentrations at this time point were significantly (P = 0.014) higher in the OHSS group as compared to the control group. At the time of discharge from the hospital (DIS), the concentrations of inhibin A of the OHSS patients had decreased to concentrations similar to those of the control group at >=3 days post-embryo transfer.



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Figure 1. Concentrations of inhibin A in serum of ovarian hyperstimulation syndrome (OHSS) patients and control patients. Data are presented as mean ± SEM. *Significantly (P = 0.014) higher than control group (G-ST = gonadotrophin stimulation start, ASP-3 = 3 days before aspiration, ASP = day of aspiration, ET = embryo transfer day, P-ET = >=3 days after embryo transfer, DIS = day of hospital discharge of OHSS patients).

 
The inhibin A concentrations of the control group at ASP-3, ASP and embryo transfer showed positive correlations with the total numbers of follicles (r = 0.47, P = 0.01 for ASP-3; r = 0.41, P = 0.04 for ASP (Figure 2AGo); r = 0.49, P = 0.01 for embryo transfer) and with the number of large follicles (r = 0.64, P = 0.0001 for ASP-3; r = 0.54, P = 0.003 for ASP; r = 0.59, P = 0.0002 for embryo transfer). These correlations did not exist in the OHSS group apart from a positive correlation between the total number of follicles and inhibin A concentrations at ASP (r = 0.68, P = 0.009, Figure 2BGo). Analysis of correlations between inhibin A concentrations at ASP-3, ASP or embryo transfer with oestradiol concentrations at ASP-3 showed no correlation except at ASP-3 of the control group (r = 0.53, P = 0.002).



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Figure 2. Correlation at ASP between inhibin A concentration and total number of follicles in (A) control patients (r = 0.41,P = 0.04) and (B) OHSS patients (r = 0.68, P = 0.009).

 
Inhibin B concentrations
The concentrations of inhibin B were very low (<15 pg/ml) at the start of ovarian stimulation and peaked at ASP-3 (Figure 3Go). At this time point, the concentrations in the OHSS group (3554 ± 519 pg/ml) were significantly (P = 0.0013) higher than the concentrations in the control group (2034 ± 182 pg/ml). Subsequently, the concentrations decreased to about half of this value at ASP. The concentrations in the OHSS group were still at this timepoint significantly (P = 0.016) higher than the concentrations in the control group. No differences between the groups were seen either at embryo transfer or >=3 days post-embryo transfer, where the concentrations were back to starting concentrations.



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Figure 3. Concentration of inhibin B in serum of OHSS patients and control patients. Data are presented as mean±SEM. Significantly (***P = 0.0013, *P = 0.016) higher than control group (G-ST = gonadotrophin stimulation start, ASP-3 = 3 days before aspiration, ASP = day of aspiration, ET = embryo transfer day, P-ET = <=3 days after embryo transfer, DIS = day of hospital discharge of OHSS patients).

 
The inhibin B concentrations of both the control and OHSS group at ASP-3 showed a positive correlation with the total number of follicles as determined at ASP (r = 0.48, P = 0.0095 and r = 0.54, P = 0.047 respectively; Figure 4Go) but no correlation was evident at ASP or embryo transfer. Unfortunately, detailed data on follicle sizes were only available at ASP, not at ASP-3. There were no correlations between the number of large follicles or the oestradiol values at ASP-3 with inhibin B concentrations at any time point.



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Figure 4. Correlation between inhibin B concentration at ASP-3 and total number of follicles at ASP in (A) control patients(r = 0.48, P = 0.0095) and (B) OHSS patients (r = 0.54,P = 0.047). Detailed data on follicle size and number were not available at ASP-3.

 
No correlations were found between inhibin A and B either in the OHSS group at ASP-3, ASP or embryo transfer or in the control group except for at ASP where a positive correlation was found. (r = 0.59, P = 0.0007, Figure 5Go).



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Figure 5. Correlation between inhibin A and B concentrations (pg/ml) of control patients at ASP (r = 0.59, P = 0.0007).

 

    Discussion
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 Materials and methods
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The present study is the first to evaluate the peripheral blood concentrations of inhibin A and inhibin B in patients developing OHSS. The study was performed as one part of a large prospective cohort study (Enskog et al., 1999Go), where serum samples were collected for use in analysis of blood markers for OHSS during ovarian stimulation. The general patterns of inhibin A and inhibin B concentrations in the peripheral circulation of both OHSS patients and control patients were essentially consistent with those earlier reported to occur during gonadotrophin stimulation in non-OHSS patients (Lockwood et al., 1996Go). Additionally, the present study identified marked and significant differences in inhibin concentrations between OHSS patients and controls at certain time points. It was found that the concentrations of inhibin A increased gradually in both groups and with no significant differences up to and including the stage of embryo transfer. In OHSS patients, the inhibin A concentrations remained high after embryo transfer, in contrast to decreased concentrations after embryo transfer in the control population. The elevated inhibin A concentrations in the OHSS patients decreased during treatment, to similar concentrations at DIS as those of the control group at >=3 days post-embryo transfer. The pattern of inhibin B concentrations was different, with low concentrations at the start of ovarian stimulation, peak concentrations at ASP-3, and subsequently decreasing concentrations with low values on the day of embryo transfer. The mean concentrations of inhibin B at ASP-3 and at ASP were 2-fold higher in the OHSS group as compared to the control group.

In the present study, the control group consisted of patients from the same IVF cohort, who were matched regarding both age and follicle numbers. Traditionally, most studies comparing various factors in blood or ascites of OHSS patients with a control population have not attempted to reduce confounding factors by any matching or only used age as the matching factor, since it has been described that patients of lower age are more prone to develop OHSS (Navot et al., 1988Go). Apart from age, follicle number was also included as a matching factor to reduce the possibility that measured differences in inhibin concentrations would only be due to variances in follicle numbers. It has been suggested that patients developing OHSS may have a larger number of developing follicles (Blankstein et al., 1987Go; Enskog et al., 1999Go). Thus any observed variance in inhibin concentrations in a follicle-unmatched situation could simply be due to this difference in follicle numbers. In the clinical situation of predicting OHSS risk, this could of course be more directly and easily detected by TVS.

Inhibin B is considered to be produced primarily by antral follicles and especially by the dominant follicle of the natural unstimulated cycle (Groome et al., 1996Go). The finding that inhibin B concentrations are considerably higher than inhibin A concentrations in human follicular fluid obtained from the natural cycle (Magoffin and Jakimuk, 1997Go) also supports this. In the partly unphysiological situation of ovarian stimulation, the natural selection mechanisms are disrupted and a large cohort of follicles, with the assumed capacity to produce large quantities of inhibin B, will develop to or near to the ultimate differentiation stage of the pre-ovulatory follicle. The results of the present study, with considerably higher inhibin B concentrations in the OHSS group during the later stages of ovarian stimulation cannot be explained by a greater number of maturing follicles in the OHSS group (see above). It is instead suggested that the follicles of the OHSS patients may have, on a per follicle basis, a higher production of inhibin B as compared to the control cases. This may of course be due to higher gonadotrophin sensitivity of the granulosa cells in regards to inhibin B production. The existence of a wide variation in follicular production of inhibin B, at least in the natural cycle, is supported by a recent study demonstrating the concentrations of inhibin B in follicular fluid of healthy dominant follicles to be highly variable, in contrast to the concentrations of inhibin A which are more uniform (Magoffin and Jakimuk, 1997Go). The variability in inhibin B production in the ovarian stimulation situation is shown by the results of the present study, where in relation to inhibin A, there was a poorer correlation with number of follicles. In the case of ovarian stimulation, a general view is that follicular size is correlated with the differentiation stage and maturity of the follicle (Andersen, 1993Go; Ectors et al., 1997Go). A poor correlation between follicle size and fertilization capacity of oocytes obtained at IVF has also been described (Salha et al., 1998Go). The notion that other variables than size better reflect follicle differentiation is demonstrated by the finding that follicular blood flow may be a better measurement of oocyte viability than actual size (Chiu et al., 1997Go).

Another possible explanation for the difference in inhibin B concentrations during ovarian stimulation is that in the OHSS patients there are additional ovarian sites of inhibin B production, which are not directly reflected by the TVS appearance. Thus, a large inhibin B production from smaller follicles, which are not seen on TVS, from stromal elements, may exist.

It is well known that ovarian inhibin B production is partly FSH-driven (Lockwood et al., 1998Go) and it could be assumed that the difference in inhibin B concentrations during ovarian stimulation could have been due to higher doses of FSH given to the OHSS group. However, it is unlikely that the inhibin concentrations are directly related to gonadotrophin dose in this situation, since the OHSS group had higher inhibin B concentrations after receiving a lower gonadotrophin dose.

Since inhibin B concentrations were not different in the OHSS group and the control group at OHSS onset, it is unlikely that this hormone is responsible for the acute effects of the disease, such as ascites formation. Thus, it may be speculated that the high inhibin B concentrations before OHSS onset may instead be related to intra-ovarian mechanisms which in some way prepare the follicle, upon HCG stimulation, to produce large quantities of some factors which directly cause the enormous vascular permeability of the ovaries and of the peritoneal surfaces, which is supposed to be the underlying mechanism responsible for the clinical manifestations of OHSS (Tollan et al., 1990Go).

The increased inhibin A concentrations after embryo transfer in the OHSS group show that the production of this glycoprotein is increased in the large hyperpermeable OHSS ovaries. The subunits of this inhibin are expressed in human luteinized granulosa cells and these cells secrete the dimeric form (Erämaa and Ritvos, 1996Go). Interestingly, the secretion from these luteinized cells is stimulated by prostaglandin E2 (Erämaa and Ritvos, 1996Go). This prostaglandin is produced in large quantities in the human corpus luteum (Patwardhan and Lanthier, 1980Go) and may be of pathophysiological significance in OHSS, since increased concentrations in the peritoneal cavity of OHSS patients have been found (Schenker and Polishuk, 1976Go). It is also possible that inhibins may contribute to the pathophysiology of OHSS by their chemotactic properties on monocytes/macrophages (Petraglia et al., 1991Go). This cell type is present around the ovulating follicle (Brännström et al., 1994Go) and macrophages have the capacity to secrete large quantities of vasoactive substances such as eicosanoids and platelet activating factor upon activation.

Low age is a well-known risk factor for OHSS (Delvigne et al., 1993Go), which was also confirmed in our recent one centre prospective study (Enskog et al., 1999Go). The exact mechanisms behind the age factor in OHSS development is not clear but is most probably related to the larger ovarian reserve in younger women. Inhibin concentrations show fluctuations during the menstrual cycle and lower concentrations are found in older women (>35 years of age) during ovulation induction (Hughes et al., 1990Go). A correlation between ovarian reserve and inhibin B concentrations is further suggested by the poorer response to ovulation induction in women with low day 3 serum inhibin B concentrations (Seifer et al., 1997Go). In the present study, the mean age of the OHSS patients and the control group was exactly the same and the results obtained should not have been confounded by age.

The {alpha} inhibin subunit, which is present in both inhibin A and inhibin B, seems to be produced in excess, since the concentrations of the free form of this subunit in blood are high (Lockwood et al., 1998Go). The production of the {alpha} subunit in the follicle is stimulated by FSH and also by ovarian-derived factors such as activin A and insulin growth factor-I (Kubo et al., 1998Go) which by autocrine/paracrine mechanisms would stimulate inhibin expression in granulosa and theca cells. In the present study, the total dose of gonadotrophins given in the OHSS group was lower than in the control group. The increased inhibin concentrations in the OHSS situation cannot be explained by greater gonadotrophin influence and intraovarian paracrine mechanisms such as those mentioned above; however, intrinsic increased gonadotrophin responsiveness may be an explanation.

In conclusion, the concentrations of inhibins were shown to be higher in patients developing OHSS. The concentrations of inhibin B, even before HCG administration, may serve as indicators of OHSS risk and allow for corrective measures to be undertaken in time and inhibin A measurements may be used to monitor the disease. Studies aimed at finding the threshold values of inhibin B to predict OHSS are ongoing in our unit.


    Acknowledgments
 
This study was supported by grants from the Swedish Medical Research Council (11607 to M.B.) and the research foundations of Hjalmar Svensson, Göteborg Medical Association, and Medical Faculty of Göteborg University.


    Notes
 
1 To whom correspondence should be addressed Back


    References
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 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Abramov, Y., Barak, V., Levy, Y. et al. (1997) Vascular endothelial growth factor plasma levels correlate to the clinical picture in severe ovarian hyperstimulation syndrome. Fertil. Steril., 67, 261–265.[ISI][Medline]

Andersen, C.Y. (1993) Characteristics of human follicular fluid associated with successful conception after in vitro fertilization. J. Clin. Endocrinol. Metab., 77, 1227–1234.[Abstract]

Araujo, E., Jr, Bernardini, L., Frederick, J.L. et al. (1994) Prospective randomised comparison of human chorionic gonadotrophin versus intramuscular progesterone for luteal support in assisted reproduction. J. Assist. Reprod. Genet., 11, 74–78.[ISI][Medline]

Baird, D.T. and Fraser, I.S. (1975) Concentration of oestrone and oestradiol in follicular fluid and ovarian venous blood of women. Clin. Endocrinol., 4, 259–266.[ISI][Medline]

Baird, D.T. and Smith, K.B. (1993) Inhibin and related peptides in the regulation of reproduction. Oxf. Rev. Repr. Biol., 15, 191–232.

Bergh, C., Werner, C., Nilsson, L. et al. (1995) Cumulative birth rates following cryopreservation of all embryos in stimulated in vitro fertilization (IVF) cycles. J. Assist. Reprod. Genet., 12, 191–194.[ISI][Medline]

Blankstein, J., Pariente, C., Shalev, J. et al. (1987) Ovarian hyperstimulation syndrome: prediction by number and size of preovulatory ovarian follicles. Fertil. Steril., 47, 597–602.[ISI][Medline]

Brännström, M., Pascoe, V., Norman, R.J. et al. (1994) Localisation of leukocyte subsets in the human follicle wall and in the corpus luteum throughout the menstrual cycle. Fertil. Steril., 61, 488–495.[ISI][Medline]

Burns, W.N., McGrill, J.R., Roy, A.K. et al. (1990) Expression of the human inhibin-{alpha} subunit gene in preovulatory granulosa–theca cells. Am. J. Obstet. Gynecol., 162, 273–277.[ISI][Medline]

Chiu, D.K., Pugh, N.D, Walker, S.M. et al. (1997) Follicular vascularity – the predictive value of transvaginal power Doppler ultrasonography in an in-vitro fertilization programme: a preliminary study. Hum. Reprod., 12, 191–196.[ISI][Medline]

Delvigne, A., Demoulin, A., Smitz, J. et al. (1993) The ovarian hyperstimulation syndrome in in-vitro fertilization: a Belgian multicentric study. I. Clinical and biological features. Hum. Reprod., 8, 1353–1360.[Abstract]

Delvigne, A.,Vandromme, J., Demeestere, I. et al. (1997) Unpredictable cases of complicated ovarian hyperstimulation in IVF. Int. J. Fertil. Women's Med., 42, 268–270.[ISI][Medline]

Devroey, P., Mannaerts, B., Smitz, J. et al. (1994) Clinical outcome of a pilot efficacy study on recombinant human follicle-stimulating hormone (Org 32489) combined with various gonadotrophin-releasing hormone agonist regimens. Hum. Reprod., 9, 1064–1069.[Abstract]

Ectors, F.J., Vanderzwalmen, P., Van Hoeck, J. et al. (1997) Relationship of human follicular diameter with oocyte fertilization and development after in-vitro fertilization or intracytoplasmic sperm injection. Hum. Reprod., 12, 2002–2005.[Abstract]

Enskog, A., Henriksson, M., Unander, M. et al. (1999) A prospective study of the patient characteristics and clinical and laboratory parameters of patients in whom ovarian hyperstimulation syndrome (OHSS) develops during controlled ovarian hyperstimulation for in vitro fertilization. Fertil. Steril., 71, 808–814.[ISI][Medline]

Erämaa, M. and Ritvos, O. (1996) Prostaglandin E2 induces inhibin-{alpha} and ß A-subunit mRNA and secretion of dimeric inhibin A in cultured human granulosa–luteal cells. Mol. Hum. Reprod., 2, 815–822.[Abstract]

Erämaa, M., Heikinheimo, K., Tuuri, T. et al. (1993) Inhibin/activin subunit mRNA expression in human granulosa–luteal cells. Mol. Cell. Endocrinol., 92, R15–R20.[ISI][Medline]

Golan, A., Ron-El, R., Herman, A. et al. (1989) Ovarian hyperstimulation syndrome: an update and review. Obstet. Gynecol. Surv., 44, 430–440.[Medline]

Groome, N.P., Illingworth, P.J., O'Brien, M. et al. (1994) Detection of dimeric inhibin throughout the human menstrual cycle by two-site enzyme immunoassay. Clin. Endocrinol., 40, 717–723.[ISI][Medline]

Groome, N.P., Illingworth, P.J., O'Brien, M. et al. (1996) Measurement of dimeric inhibin B throughout the human menstrual cycle. J. Clin. Endocrinol. Metab., 81, 1401–1405.[Abstract]

Hall, J.E., Welt, C.K. and Cramer, D.W. (1999) Inhibin A and inhibin B reflect ovarian function in assisted reproduction but are less useful at predicting outcome. Hum. Reprod., 14, 409–415.[Abstract/Free Full Text]

Hamilton-Fairley, D., Kiddy, D., Watson, H. et al. (1991) Low-dose gonadotrophin therapy for induction of ovulation in 100 women with polycystic ovary syndrome. Hum. Reprod., 6, 1095–1999.[Abstract]

Hughes, E.G., Robertson, D.M., Handelsman, D.J. et al. (1990) Inhibin and estradiol responses to ovarian hyperstimulation: effects of age and predictive value for in vitro fertilization outcome. J. Clin. Endocrinol. Metab., 7, 358–364.

Kubo, T., Shimasaki, S., Kim, H. et al. (1998) Activin-induced inhibin {alpha}-subunit production by rat granulosa cells requires endogenous insulin-like growth factor-1. Biol. Reprod., 58, 712–718.[Abstract]

Lockwood, G.M., Muttukrishna, S., Groome, N.P. et al. (1996) Circulating inhibins and activin A during GnRH-analogue down-regulation and ovarian hyperstimulation with recombinant FSH for in-vitro fertilization–embryo transfer. Clin. Endocrinol., 45, 741–748.[ISI][Medline]

Lockwood, G.M., Muttukrishna, S. and Ledger, L. (1998) Inhibins and activins in human ovulation, conception and pregnancy. Hum. Reprod. Update, 4, 284–295.[Abstract/Free Full Text]

Loret de Mola, R., Baumgardner, G.P., Goldfarb, J.M. et al. (1996) Ovarian hyperstimulation syndrome: preovulatory serum concentrations of interleukin-6, interleukin-1 receptor antagonist and tumour necrosis factor-{alpha} cannot predict its occurrence. Hum. Reprod., 11, 1377–1380.[Abstract/Free Full Text]

Magoffin, D.A. and Jakimuk, A.J. (1997) Inhibin A, inhibin B and activin A in the follicular fluid of regularly cycling women. Hum. Reprod., 12, 1714–1719.[Abstract]

Morris, R.S., Paulson, R.J., Sauer, M.V. et al. (1995) Predictive value of serum oestradiol concentrations and oocyte number in severe ovarian hyperstimulation syndrome. Hum. Reprod., 10, 811–814.[Abstract]

Navot, D., Relou, A. and Birkenfeld, A. (1988) Risk factors and prognostic variables in the hyperstimulation syndrome. Am. J. Obstet. Gyncol., 159, 210–215.[ISI][Medline]

Navot, D., Bergh, P.A. and Laufer, N. (1992) Ovarian hyperstimulation syndrome in novel reproductive technologies: prevention and treatment. Fertil. Steril., 58, 249–261.[ISI][Medline]

Navot, D., Bergh, P.A. and Laufer, N. (1995) The ovarian hyperstimulation syndrome. In Adashi, E.Y., Rock, J.A. and Rosenwaks, Z. (eds), Reproductive Endocrinology, Surgery and Technology, vol. 2. Lippincott-Raven, Philadelphia, pp. 2215–2232.

Patwardhan, V.V. and Lanthier, A. (1980) Concentrations of prostaglandins PGE and PGF, estrone, estradiol, and progesterone in human corpora lutea. Prostaglandins, 20, 963–969.[Medline]

Petraglia, F., Sacerdote, P., Cossurizza, A. et al. (1991) Inhibin and activin modulate human monocyte chemotaxis and human lymphocyte interferon-gamma production. J. Clin. Endocrinol. Metab., 72, 496–501.[Abstract]

Salha, O., Nugent, D., Dada, T. et al. (1998) The relationship between follicular fluid aspirate volume and oocyte maturity in in-vitro fertilization cycles. Hum. Reprod., 13, 1901–1906.[Abstract]

Schenker, J.G. and Polishuk, W.Z. (1976) The role of prostaglandins in ovarian hyperstimulation syndrome. Eur. J. Obstet. Gynecol. Reprod. Biol., 6, 47–52.[Medline]

Schipper, I., de Jong, F.H. and Fauser, B.C.J.M. (1998) Lack of correlation between maximum early follicular phase serum follicle stimulating hormone concentrations and menstrual cycle characteristics in women under the age of 35 years. Hum. Reprod., 13, 1442–1448.[Abstract]

Seifer, D.B., Lambert-Meserlina, G., Hogan, J.W. et al. (1997) Day 3 serum inhibin B is predictive of assisted reproductive technologies outcome. Fertil. Steril., 67, 110–114.[ISI][Medline]

Sher, G., Zouves, C., Feinman, M. et al. (1995) `Prolonged coasting': an effective method for preventing severe ovarian hyperstimulation syndrome in patients undergoing in-vitro fertilization. Hum. Reprod., 10, 3107–3109.[Abstract]

Tollan, A., Holst, N., Forsdahl, F. et al. (1990) Transcapillary fluid dynamics during ovarian stimulation for in vitro fertilization. Am. J. Obstet. Gynecol., 162, 554–558.[ISI][Medline]

Yamoto, M., Minami, S., Nakano, R. (1992) Immunohistochemical localisation of inhibin/activin subunits in human ovarian follicles during the menstrual cycle. J. Clin. Endocrinol. Metab., 74, 989–993.[Abstract]

Submitted on July 5, 1999; accepted on November 11, 1999.