A Vereecken

Bio: A Vereecken is an academic researcher from Katholieke Universiteit Leuven. The author has contributed to research in topics: Follicle-stimulating hormone & Male infertility. The author has an hindex of 3, co-authored 3 publications receiving 32 citations.

Performance of the sperm quality analyser in predicting the outcome of assisted reproduction

Abstract: The present study was undertaken to assess the relationship between the results of conventional semen analysis and the sperm motility index (SMI) as measured by the sperm quality analyser (SQA), and to evaluate these in relation to the fertilization and/or pregnancy outcome of assisted reproduction. SMI determinations and conventional semen analyses were performed on 223 samples from subfertile men in two laboratories in Leuven (n = 136) and Antwerp (n = 87), and on spermatozoa prepared on a Percoll gradient (n = 136) used for treatment of male factor infertility in 57 cycles of intrauterine insemination (IUI), 44 attempts at in vitro fertilization (IVF) and 31 attempts at intracytoplasmic sperm injection (ICSI). SMI values for native semen correlated significantly with sperm concentration, motility and morphology. Multiple regression analysis revealed sperm concentration after preparation, and the concentration of motile spermatozoa with normal morphology and SMI (before preparation) to be the independent determinants for SMI after preparation. SMI values were significantly higher after, than before, preparation (p < 0.0001). In regular IVF (n = 44) the percentage of fertilized oocytes correlated significantly (p < 0.05) with sperm motility (A + B%, r = 0.33), with the percentage of spermatozoa with normal morphology (r = 0.46) before preparation, with the values of SMI both before and after preparation (r = 0.54, r = 0.48), with sperm concentration (r = 0.34) and with the motile sperm concentration (r = 0.29) after preparation. For the occurrence of pregnancy (all treatment methods), comparison of areas under ROC curves (AURC) indicated motile sperm concentration after preparation, as well as SMI both before and after preparation, to have the highest AURC, with no significant difference between these values as far as predictive power was concerned. These results indicate that the SQA allows for rapid evaluation of sperm characteristics and of the effectiveness of sperm preparation techniques. However, it is not superior to conventional semen analysis in predicting the outcome of assisted reproduction.

Inhibin and steroid responses to testicular stimulation in normal men.

Abstract: Static measurements of immunoreactive inhibin have proved to be of little relevance in the diagnosis of testicular disorders. To explore whether a dynamic evaluation of inhibin secretion might yield a more useful parameter of testicular function we compared the responses of inhibin with steroids to i.v. injections of pure follicle-stimulating hormone (FSH ; 300 IU) or human chorionic gonadotrophin (HCG ; 1500 IU) and oral administration of the antioestrogen Tamoxifen (20 mg/day for 7 days) in four normal fertile men. Blood was aspirated between 1 and 72 h after the injections and daily during Tamoxifen intake. Four controls were injected with physiological saline solution. An additional four men were injected with pure FSH, and blood was taken after 24, 48 and 72 h. Injection of FSH was accompanied by nycthemeral variations of testosterone comparable with those observed in the controls. The concentration of inhibin showed similar nycthemeral variations but a significant increase was observed in all eight cases at 12 noon on days 2 and 3 after FSH injection. HCG injection resulted in the expected biphasic response of testosterone. Inhibin displayed a pronounced increase 18 h after injection but the delayed response after 48 and 72h was not observed. Tamoxifen intake increased testosterone but not inhibin, and caused a moderate and temporary increase of luteinizing hormone and FSH. It was concluded that primary stimulation both of Leydig cells by HCG and Sertoli cells by FSH increase circulating inhibin. Comparison with the testosterone response suggests that the inhibin peak 18 h after HCG administration may reflect Leydig cell function, and that the delayed response 48 and 72 h after FSH administration can be used as a parameter of Sertoli cell function.

Inhibin and steroid response to testicular stimulation with pure FSH (Metrodin) in infertile men with unilateral cryptorchidism.

Abstract: Static measurements of immunoreactive inhibin have proven of little relevance in the diagnosis of testicular disorders. Dynamic evaluation of the inhibin secretory reserve might detect a specific Sertoli cell defect in a subgroup of infertile men. We compared the response of inhibin and steroids to an intravenous injection of pure FSH (Metrodin, Serono, 300 IU) in 13 infertile men with unilateral cryptorchidism to that in eight normal fertile men. Blood was aspirated before, 24, 48, and 72 h after the FSH injection. Two subgroups of patients with unilateral cryptorchidism were detected : those who responded by secreting inhibin in a pattern similar to normal men (seven patients), and those who responded poorly or not at all (six patients). The presumed cause of this difference is a defect of Sertoli cell reserve function due to a combination of insults to the testes, and not to cryptorchidism itself. The difference in response to FSH cannot be predicted from semen analysis nor from static hormone measurements. Overall, inhibin levels correlated significantly with the serum concentrations of FSH (r= -0.36, P<0.05), testosterone (r=0.37, P<0.05), and 17-hydroxyprogesterone (r=0.66, P<0.001). It is concluded that, in infertile men with unilateral cryptorchidism, stimulation of Sertoli cells by FSH can identify a subgroup of patients with Sertoli cell malfunction involving inhibin synthesis.

Serum inhibin B in healthy pubertal and adolescent boys: relation to age, stage of puberty, and follicle-stimulating hormone, luteinizing hormone, testosterone, and estradiol levels.

Abstract: Inhibin B levels were measured in serum from 400 healthy Danish prepubertal, pubertal, and adolescent males, aged 6-20 yr, in a cross-sectional study using a recently developed immunoassay that is specific for inhibin B, the physiologically important inhibin form in men. In addition, serum levels of FSH, LH, testosterone, and estradiol levels were measured. Serum levels of inhibin B, FSH, LH, testosterone, and estradiol all increased significantly between stages I and II of puberty. From stage II of puberty the inhibin B level was relatively constant, whereas the FSH level continued to increase between stages II and III. From stage III of puberty the FSH level was also relatively constant, although there was a nonsignificant trend of slightly decreased FSH levels at pubertal stage V compared to stage IV. The levels of serum LH, testosterone, and estradiol increased progressively throughout puberty. In prepubertal boys younger than 9 yr, there were no correlation between inhibin B and the other three hormones. In prepubertal boys older than 9 yr, a significant positive correlation was observed between inhibin B and FSH, LH, and testosterone. However, at this pubertal stage, each hormone correlated strongly with age, and when the effect of age was taken into account, only the partial correlation between inhibin B and LH/testosterone remained statistically significant. At stage II of puberty, the positive partial correlation between inhibin B and LH/testosterone was still present. At stage III of puberty, an negative partial correlation between inhibin B and FSH, LH, and estradiol was present, whereas no correlation between inhibin B and testosterone could be observed from stage III onward. The negative correlation between inhibin B and FSH persisted from stage III of puberty onward, whereas the correlation between inhibin B and LH and between inhibin B and estradiol was nonsignificant at stages IV and V of puberty. In conclusion, in boys, serum inhibin B levels increase early in puberty; by pubertal stage II the adult level of inhibin B has been reached. The correlation of inhibin B to FSH, LH, and testosterone changes during pubertal development. Early puberty is characterized by a positive correlation between inhibin B and LH/testosterone, but no correlation to FSH. Late puberty (from stage III) is characterized by a negative correlation between inhibin B and FSH (which is maintained in adult men), a diminishing negative correlation between inhibin B and LH, and no correlation between inhibin B and testosterone, suggesting that developmental and maturational processes in the hypothalamic-pituitary-gonadal axis take place, leading to the establishment of the closed loop feedback regulation system operating in adult men. The positive correlation between inhibin B and LH/ testosterone at the time when serum inhibin B levels rise early in puberty suggests that Leydig cell factors may play an important role in the maturation and stimulation of Sertoli cells in the beginning of pubertal development.

Basal Inhibin B and the Testosterone Response to Human Chorionic Gonadotropin Correlate in Prepubertal Boys

Abstract: During childhood, the quiescent phase of testicular activity, the hCG stimulation test is widely used to evaluate testicular function. Inhibin B, a gonadal peptide regulating FSH secretion, is an established marker of Sertoli cell function and spermatogenesis in adults. In contrast to the other hormones of the hypothalamo-pituitary-gonadal axis, inhibin B is also secreted in detectable amounts during childhood. The aim of this study was to determine whether basal inhibin B levels are able to predict prepubertal testicular function, so as to avoid a stimulation test. Inhibin B and testosterone before and after hCG stimulation were measured in 54 male children with various testicular disorders by an immunoassay specific for inhibin B. Basal inhibin B was compared to the testosterone increase after hCG. Inhibin B and the hCG-induced testosterone increment correlated strongly (r = 0.84; P<0.0001). Patients with anorchia were clearly distinguishable from those with abdominal testes, having undetectable (inhibin B, <15 pg/mL) respective normal inhibin B levels for age. Inhibin B and the testosterone response to hCG were low in boys with testicular damage (delayed diagnosis of cryptorchidism; after testicular torsion) and in patients with gonadal dysgenesis, but were normal or increased in children with androgen insensitivity syndrome. We conclude that basal inhibin B predicts the testosterone response to hCG in boys and therefore gives reliable information about both the presence and function of the testes. The diagnostic procedure in cryptorchidism may be reduced to a single inhibin B measurement. Furthermore, inhibin B levels show specific alterations in patients with sexual ambiguity, adding a valuable diagnostic tool to the complex differential diagnosis of male pseudohermaphroditism.

Evaluation and Treatment of Cryptorchidism

Abstract: Authors' conclusions The body of the reviewed literature on cryptorchidism comprise primarily fairand poor-quality studies, which limits our ability to draw definitive conclusions. No specific imaging technique is able to completely identify anorchia or position of the undescended testicles and thus eliminate the need for further surgical evaluation. Accuracy of imaging is related to location of the testicles, with less invasive methods demonstrating poor accuracy for abdominally located testicles and those that are atrophied. Hormonal stimulation testing may predict anorchia, but evidence is insufficient, with only two studies of fewer than 50 participants. Hormonal treatment is marginally effective relative to placebo, but it is successful in some children and has minimal side effects, suggesting that it may be an appropriate trial of care for some patients. Surgical options are effective, with high rates of testicular descent (moderate strength of evidence for Fowler-Stephens procedures, high for primary orchiopexy). Comparable outcomes occur with laparoscopic and open approaches.