Once a woman has tested fsh levels over 100 iu/ml is it likely that later tests (6 months later for example) will reveal fsh back into normal or near normal follicular phase range. i have heard that this is highly unlikely?

At age "43",with "FSH 100 iu/ml" the FSH level is consistent with menopausal levels. While occasional spontaneous ovulation may occur, it is unlikely. Ask your GYN physician about low dose oral contraceptives, to stop ovarian function, reduce menopausal symptoms ("hot flashes", depression, vaginal dryness, etc.). Oral bcp's may be taken without the usual "placebo" break for several packs.