To Understand Menopause it helps to understand how our hormone’s behave before we reach midlife and menopause
Hormones before menopause work on a cycle controlled by the pituitary gland just underneath the very centre of the lower surface of the brain. This little gland is the ‘conductor’ of the orchestra of endocrine glands in the body, including the thyroid, the adrenals, and the ovaries or testes.
The pituitary is organised on a bio-rhythm sort of cycle, some say related to the phases of the moon. There is good evidence to show that this may well be true! It also responds to what is going on in the brain, at least to some extent. The brain is the ‘commander in chief’. If there is some sort of huge trauma going on, a big shock or critical performance issues such as chronic long distance running or long term starvation, the hypothalamus part of the brain, which lies geographically above the pituitary, can communicate with the little gland almost instantaneously to affect its output.
Before menopause in a normal woman, the pituitary puts out FSH or Follicle Stimulating Hormone to stimulate the ovaries to develop and then release an ovum or egg for fertilisation. Since the reproduction of the species depends on this cycle of FSH and ovarian response, it takes a major impact of some sort to disturb the pituitary so that it stops stimulating the ovaries. But under normal circumstances the FSH during the fertile years runs at anything from 3 to 30 or thereabouts.
So, what about progesterone, the ‘forgotten’ hormone?
Well progesterone is produced in the ovary after the egg has been released for fertilisation. The body produces heaps of progesterone but only in the second half of the cycle, so as to ensure that the new embryo, if present, has the best possible chance of being properly embedded in the uterine wall and the woman’s early pregnancy proceeds without problems. A low progesterone output during the second half of the ovarian cycle will often indicate an inability to carry a fertilised egg into later pregnancy. The IVF clinics around the world, and also in Australia where it all began, will give their patient progesterone routinely to ensure the best possible environment for the fertilised egg.
So if you only have progesterone after ovulation, then a pre-menopausal woman only need progesterone from Day 10 or 12 to the next period. But it is different in menopause. The whole hormone orchestra changes because of the slow, or no, ovarian response to FSH. The pituitary continues to try to stimulate the sluggish ovaries, and puts out increasing amounts of FSH, which can go up to 300-350 before the pituitary recognises that there is never going to be any response from the ovaries, and it slowly reduces the amount of FSH.
Slight or absent ovarian response also means there is less oestrogen running around the blood stream. The combination of high FSH + low oestrogen (not merely low oestrogen alone) is what causes the hot flushes. We know this because when the FSH reduces back down, even when there is less than 10 units of oestrogen, there is no hot flushing! At that point the woman has successfully traversed the menopause and is now post-menopausal.