רמת אינהיבין

ניתן לבצע בדיקת אינהיבין במעבדות פרטיות רבות בישראל. מפנים את האישה לעשות זאת כאשר מתלבטים האם כדאי לעשות טיפולי פריון או לוותר על כך לנוכח רזרבה שחלתית נמוכה. בישראל לא מרבים להפנות לבדיקה מאחר והיא בעלת יכולת חיזוי מוגבלת, וכל הנשים שאני פגשתי לא מוכנות לוותר על ניסיון טיפול גם כאשר יש חשד לרזרבה שחלתית נמוכה על סמך בדיקת דם. פרטים נוספים: Inhibin B Its Value for Predicting Success in IVF Geralyn Lambert-Messerlian, Ph.D. For infertile couples, the decision to undergo in vitro fertilization (IVF) is a complex process, involving emotional, physical AND financial commitments. Ideally, physicians could know in advance of treatment which couples would successfully conceive a baby through IVF AND which would not, so that the latter group could be spared unnecessary efforts. Although this is currently not possible, certain indicators can be used to assess the likelihood of success in IVF prior to beginning a cycle. One new such indicator is called inhibin B. What is Inhibin B? Inhibin is a protein that is made by the ovary AND named for its role in inhibiting follicle-stimulating hormone (FSH), the hormone responsible for the development of ovarian follicles. In fact, there are two types of inhibin, made at different times of the normal menstrual cycle. Inhibin B is made from small developing follicles of the ovary during the first half (follicular phase) of the cycle, while inhibin A is predominantly made from large follicles at ovulation AND in the second half (luteal phase) of the cycle from the follicular tissue remaining after ovulation, a structure called the corpus luteum. What is Ovarian Reserve? Every female is born with a specific number of follicles containing eggs, a number which steadily AND naturally declines with age. The number of follicles remaining in the ovary at any time is called ovarian reserve. As ovarian reserve diminishes it is increasingly more difficult for the hormones used in IVF to stimulate follicle development, AND thus the likelihood of successful oocyte (egg) retrieval, fertilization AND embryo transfer decreases, all leading to a lower chance of having a baby. As part of an infertility evaluation, attempts are made to estimate a woman’s ovarian reserve. Inhibin B AND Ovarian Reserve Inhibin B is a direct product of small, developing follicles in the ovary and, as such, indicates a woman’s ovarian reserve. The amount of inhibin B measured in serum during the early follicular phase of the menstrual cycle (days 2-6) directly reflects the number of follicles in the ovary; in other words, the higher the inhibin B, the more ovarian follicles are present. Inhibin B levels decrease as women age AND ovarian follicle numbers decline Inhibin B levels also predict the ability of the ovary to grow follicles in response to hormone treatment used for IVF. Research studies have shown that the amount of inhibin B in the follicular phase of the menstrual cycle indicates the number of oocytes that will be retrieved after hormonal stimulation treatments. A higher follicular phase inhibin B level is associated with a better ovarian reserve AND a higher number of follicles (oocytes) that develop in response to hormone stimulation. Moreover, it has been reported that women with very low inhibin B levels (<20 pg/mL) often have such a poor ovarian response that the IVF cycle must be cancelled. Other Markers of Ovarian Reserve Other methods are used to assess ovarian reserve. These include age AND serum FSH levels. While age is undoubtedly an indicator of ovarian reserve, there are some cases of infertility due to premature loss of follicles, meaning that a relatively young woman has reduced her “reserve” at an accelerated pace. Serum FSH is the blood test most often used to assess ovarian reserve, but unlike inhibin B it is an indirect measure of ovarian follicles. FSH is a product of the pituitary gland AND is regulated by ovarian hormones like inhibin B AND estradiol. Levels of FSH are increased when ovarian reserve is diminished. Serum FSH measurement has some limitations in assessment of ovarian reserve. First, FSH levels are reported to fluctuate from month to month, with variation in the range of 20-40%. Inhibin B has less intercycle variation, with patient levels remaining within 10% over consecutive monthly determinations. Second, although a very high level of FSH is likely to indicate a poor response in IVF, it is more difficult to make an assessment for patients with lower FSH levels (around 10 mIU/mL OR less). Inhibin B has been shown to aid in discriminating IVF response among women with “normal” FSH levels. In fact, a combination test of inhibin B AND FSH was found to best predict the number of oocytes retrieved. Other studies discussed the use of ultrasound to estimate follicle number AND predict oocyte retrieval. Counts of less than three predicted poor response to hormonal stimulation. The addition of serum FSH AND inhibin B measurement increased the predictive power of the follicle count test. Large studies are still needed to address the possibility of combining age, FSH, inhibin B AND possibly ultrasound measurements like ovarian volume OR follicle counts to predict ovarian response in IVF. Inhibin B Levels During Ovarian Stimulation for IVF Several studies have also shown that inhibin B measured during hormonal stimulation for IVF is highly predictive of oocytes retrieved. Eldar-Geva AND colleagues (2000) found that inhibin B levels measured during FSH administration predicted the number of oocytes retrieved. Other Variables that Influence Inhibin B Levels in Women Factors other than ovarian reserve are known to influence inhibin B levels. Polycystic ovary syndrome (PCOS), a known cause of infertility, is characterized, among other things, by many small follicles in the perimeter of the ovary. It follows then that inhibin B levels tend to be increased in women with PCOS. (Lockwood 2000) In contrast, obesity is reported to have an inhibitory effect on serum inhibin B levels. How is Inhibin B Testing Performed? The inhibin B test is performed on a blood sample drawn in the early follicular phase of the menstrual cycle (days 2-6). Depending on the results, patients should consider starting an IVF cycle within three months of the sample draw.