So we know we don't want to go too low with estradiol or we could end up with brittle bones and hip fractures like a lot of 75 year old women struggle with. Furthermore, common sense dictates that more is not better when it comes to estradiol. Many men who go on HRT and end up with estradiol in the 40's and 50's very commonly have a certain suite of side effects: gyno, water retention, lowered libido, loss of erectile strength, moodiness, poor sleep etc. If you've been around Peak Testosterone Forum at all, you know this is actually quite common. And many experts have concern about long term effects as well, because high estradiol may increase clotting risk, arterial plaque and prostate issues as I mentioned.
Follicle Stimulating Hormone (FSH) - In women FSH is often used as a gauge of ovarian reserve. In general, under 6 is excellent, 6-9 is good, 9-10 fair, 10-13 diminished reserve, 13+ very hard to stimulate. In PCOS testing, the LH:FSH ratio may be used in the diagnosis. The ratio is usually close to 1:1, but if the LH is higher, it is one possible indication of PCOS. Basic hormone testing for males often only includes testosterone and FSH. However, in cases such as Klinefelters Syndrome doctors will usually look at both FSH and LH levels. In males FSH stimulates the Sertoli cells in the testes to produce androgen-binding proteins, testosterone, and a protein called inhibin. Inhibin, in turn, travels in the blood back to the pituitary gland whre it creates a "negative feedback loop" that decreases the output of FSH. Since FSH stimulates testosterone production, and testosterone can be converted to DHT and estradiol, an increase of any or all three can also create a "feedback loop" that decreases FSH secretion.