Q,1: Which agents controls FSH level in blood ? Ans: FSH
release from pituitary is tonicaly inhibited by inhibin B which is released from granulosa cells of follicles.
If FSH level is found high then always one should think of something wrong in
Ovaries primarily.
Q.2. What about LH
control? Ans:
By contrast , when one faces a report of
high LH
then the treating physician should consider a primary defect in hypo/
ant Pit. But the FSH level is primarily
controlled by ovaries not by hypothalamus.
Q. 3:
Changes in FSH & LH in perimenopause? Ans. As a woman ages or in cases of say failing
ovarian reserve (POF-DOR) there will be less Inhibin B in
circulation due to less functioning of
active granulosa cells in the gonads . Incidentally such granulosa cells also
secrete AMH. However, in cases of POF/
aged women as FSH suppression by
inhibin B is withdrawn as happens in cases of dwindling ovarian reserve, so
level of basal FSH slowly rises.
Normally this is observed from late 4th decade of
life even in perfectly healthy parous women. FSH rise will be slow but steady from age 35
yrs onwards. . Two consecutive FSH values on day 3 of spont period or day 5 of
induced period = a FSH of > 10 ( at an interval of 3 months) means
failing Ovarian function and two reports
of (at an interval of 3 months) >
20 warrants donor egg, if couple is
interested in fertility. “FSH-Inhibin B” is a
long loop suppression of FSH (both in males & females) .
Q.4 : What is then the short loop control of FSH secretion from
basophilic cells of adenohypophysis?? Ans:
The short loop stimulation is by GnRH which however primarily looks after LH
level and has poor control on FSH level.
Q. 5 . What happens at Pituitary?? :-There should be priming of Pit by
E2 before Pit becomes eligible to response to GnRH. This is more relevant in cases of LH release
from Pit. With the advent of puberty there is sudden gain in ht & wt as
such more peripheral oestrogens from adipose tissues which help to make ant Pit
cells sensitive to GnRH (LH RH) .Therefore in cases of Weight loss nervosa-
there will be less LH release than FSH. By contrast in midcycle when serum
level of E2 is highàthere will be more release of LH (Mid cycle surge)-> Ovulation.
Q.6: What are the
causes of high LH?? Causes of high LH > 10 mIU/ml are as follows
e.g. 1) Menopause, 2) PCOS in about 40%
of all PCOS. & 3) Midcycle surge. More is the level of LH less will be
chance of pregnancy. Therefore down regulation is often proposed. Pre-induction
by OCP/ Progesterone does not always help. Whenever the LH level is below the level
of < 2 mIU/ml/à it implies that the cause is either in Pituitary or in hypothalamus.(WHO
Class I anovulation)
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