The diagnostic value of inhibin B is performed ONLY at woman’s 3rd day of the cycle in order to help to evaluate the quality of the eggs and the reservoir of the ovaries.
Inhibin B plays often a dominant role when and how a couple can conceive, and in the RSAs of the first trimester.
What is Inhibin B?
Inhibin B is primarily produced by small developing follicles. Inhibin B levels increase early in the follicular phase to reach a peak coincident with the onset of the midfollicular phase decline in FSH levels. Inhibin B levels decrease in the late follicular phase. There is a short-lived peak of the hormone 2 days after the midcycle luteinizing hormone (LH) peak. Inhibin B levels remain low during the luteal phase of the cycle. The timing of the inhibin B rise suggests that it plays a role in regulation of folliculogenesis via a negative feedback on the production of FSH. At menopause, with the depletion of ovarian follicles, serum inhibin A and B decrease to very low or undetectable levels.
Inhibin B and Fertility
Inhibin B is connected directly with fertility and the low levels in the serum is related to:
The blockage of ovulation
The low successful rates of IVFs
Low pregnancy percentages
Increased chances for RSAs
What is the benefit for testing inhibin B
Unfortunately, inhibin B is not tested in most centers in Greece, and its prognostic value is not taken in consideration in the IVF failures due to the femaile genetic part. The maximum benefits from the testing are for the following criteria:
For women with poor response in the drugs for IVF trials
For the test response in ovaries with Clomiphene
For inexplained infertility
For women with age greater than 35 years
Interpretation of results for Inhibin B
Normal values for inhibin B in serum range at 45 pg/mL. Low value for inhibin B is considered below 45 pg/mL and is not normal. This low value is related to low possibility for successful pregnancy and increased risk for RSAs. However, the low levels of inhibin B does not exclude that a woman cannot be pregnant.
The treatment includes various drugs and dietary supplements, which contribute in the increase of inhibin b and the quality of the eggs for the best result and increase of the pregnancies rates..
S.L.Corson1 , 3 , J.Gutmann1 , F.R.Batzer1, H.Wallace1, N.Klein2 and M.R.Soules. (1999) Inhibin-B as a test of ovarian reserve for infertile womenS. Human Reproduction vol.14 no.11 pp.2818-2821,
Hansen, L.M., Batzer, F.R., Gutmann, J.N. et al (1996) Evaluating ovarian
reserve: follicle stimulating hormone and oestradiol variability during cycle
days 2-5. Hum. Reprod., 11, 485-489.
Hofmann, G.E., Danforth, D.R. and Seifer, D.B. (1998) Inhibin-B: the
physiologic basis ofthe clomiphene citrate challenge testfor ovarian reserve
screening. Fertil. Steril., 69, 474-477.
Robertson, D., Burger, H.G., Sullivan, J. et al. (1996) Biological and
immunological characterization of inhibin forms in human plasma. J. Clin.
Endocrinol. Metab., 81, 669-776.