"If the estradiol level is high, the FSH level will be artificially lowered, and the FSH level will therefore not accurate. For example, I may have a patient with an FSH an 18 and an estradiol level of 45. Next month the FSH is 8, but the Estradiol is 92. This is just as bad as her first test. Once the estradiol is over about 50, the FSH will be lowered. Just because the FSH becomes lower does not mean the patient is more fertile. If the estradiol is elevated month to month, this is as bad as the FSH being elevated month to month.Why does the Estardiol level become elevated? For some women, the cycle gets shorter as their ovaries age. So that by day 3, when the follicle should not yet be growing, the follicle has already started to grow and produce estradiol, and for reasons we don’t yet understand, this is bad. "