Inhibin A is low in the early follicular phase and rises at ovulation to maximum levels in the mid-luteal phase. In contrast, inhibin B levels
increase early in the follicular phase
to reach a peak coincident with the onset of the mid-follicular phase decline in FSH levels.
What is inhibin A and inhibin B?
Inhibin A and inhibin B are
hormones associated with reproduction and the development of oocytes (immature egg cells) in women’s ovaries
. In women, these hormones are made mostly by the ovaries and by the placenta during pregnancy. Additionally, inhibin A and/or B may be produced by certain types of ovarian tumors.
What is an inhibin B test for?
Inhibin B is a
hormone associated with reproduction and the development of eggs in women and sperm in men
. This test measures the inhibin B level in the blood and may be used as part of an infertility evaluation.
What does inhibin B do in females?
The main function of inhibin in women is
regulation of pituitary FSH secretion
. One study showed that a decrease in serum inhibin concentrations could be observed when the ovarian follicular reservoir begins to diminish.
What does inhibin B regulate?
Inhibin B is a dimer of an alpha and a betaB subunit. It is produced exclusively by the testis, predominantly by the Sertoli cells in the prepubertal testis, while the site of production in the adult is still controversial. Inhibin B controls
FSH secretion via a negative feedback mechanism
.
What is a normal inhibin B level?
The normal range of inhibin in post-menopausal women is
< 5 pg ml-1
, in pre-menopausal women 2-80 pg ml-1 (2-10 pg ml-1 in the follicular phase, 40-80 pg ml-1 in the luteal phase).
What causes high inhibin levels?
Conclusion. The level of elevated Inhibin A in pregnancy is significantly related to the
outcome of pre-eclampsia, GDM, macrosomia, low birth weight and preterm delivery
.
What does the hormone inhibin do?
Inhibin is a protein secreted by the Sertoli cells in men and by the granulosa cells in women. It
inhibits the synthesis and release of the follicle-stimulating hormone in the pituitary gland and reduces the hypothalamic LH – releasing hormone content
.
Is granulosa cell tumor malignant?
GCTs are thought to be
tumors of low malignant potential
. Most of these tumors follow a benign course, with only a small percentage showing aggressive behavior, perhaps due to early stage at diagnosis. Metastatic disease can involve any organ system, although tumor growth usually is confined to the abdomen and pelvis.
What does high inhibin A mean?
High levels of maternal serum inhibin-A in the second trimester are significantly associated with
abnormal placentation
, which increases the risk of preeclampsia and FGR with a consequence of indicated preterm birth but not a risk of spontaneous preterm birth.
Does inhibin B affect LH?
Taken together, these studies indicate that control of inhibin B secretion is dependent on FSH, but
not LH
, during the early stages of follicular growth.
What type of hormone is inhibin?
Inhibin is
a dimeric 32-kD glycoprotein hormone
that participates in the regulation of the pituitary-gonadal feedback system. Inhibins secreted in the ovary consist of an α-subunit linked to one of two β-subunits.
What can affect inhibin A levels?
- If you smoke. This may increase the level of inhibin A in the blood.
- If you are obese. This may decrease the level of inhibin A in the blood.
How does inhibin regulate FSH?
Although the primary source of inhibin remains the gonad, both activin and follistatin are produced in extragonadal tissues and can exert effects on FSH through
an autocrine-paracrine mechanism
. These proteins can effect the regulation of the gonadotropins at many levels.
Where is inhibin B produced?
Inhibin B, produced by
granulosa cells in the ovary
, is a heterodimeric glycoprotein suppressing synthesis and secretion of the follicle stimulating hormone (FSH).
Why does inhibin inhibit FSH?
Inhibin does not inhibit the secretion
of GnRH from the hypothalamus. In females, inhibin is produced in the gonads, pituitary gland, placenta, corpus luteum and other organs. FSH stimulates the secretion of inhibin from the granulosa cells of the ovarian follicles in the ovaries. In turn, inhibin suppresses FSH.
