The positive feedback of estradiol on gonadotropin secretion in women with perimenopausal dysfunctional uterine bleeding.

The functionality of the hypothalamic-pituitary-ovarian axis was explored in 27 women with perimenopausal dysfunctional uterine bleeding. The positive feedback effect of estradiol on LH and FSH was studied by the estrogen challenge test, which was performed by a single i.m. injection of estradiol benzoate. An early decline of both LH and FSH was followed by an increase of LH, mainly due to the cases in which the estrogen test was positive. FSH remained low through the whole period tested. The results were compared with those found in 5 normal menstruating women. The frequency of positive estrogen tests, defined by an acute estradiol-induced discharge of LH, was lower in the perimenopausal patients (P less than 0.025). The results of the tests used in our study showed an impairment of the positive feedback system in the perimenopausal-dysfunctional-bleeding group.