[Pulsatile LH secretion and hypothalamic-pituitary function in amenorrheic women]

In order to evaluate hypothalamic-pituitary function and pulsatile LH secretion in 42 amenorrheic women, blood was collected every 20 min. for 6 hrs. The mean LH pulse frequency (LH-pf) of women with a normal cycle, PCO and hyperprolactinemia was 3.4 +/- 0.5, 5.2 +/- 0.8, and 1.6 +/- 1.0/6 hrs, respectively. Hypothalamic amenorrhea (HA) with no progesterone withdrawal bleeding showed a lower frequency of LH secretion. As LH-pf in HA with progesterone withdrawal bleeding (HAI) ranged from 0 to 5/6 hrs, the HAI group was divided into 2 groups according to whether their LH-pf was less than 3.4/6 hrs (HAIa) or more (HAIb). Pituitary response to 100 micrograms of LH-RH in HAIb was much lower than in HAIa and PCO. On the other hand, in HA with LH-pf less than 3.4, LH-pf showed a significant correlation with basal LH and FSH levels and the LH increase to 100 micrograms of LH-RH, while in HA with LH-pf greater than or equal to 3.4, LH-pf had no significant correlation with them. In PCO, a high LH pulse frequency and amplitude and LH response to 100 micrograms of LH-RH were shown, but the LH increase to 100 micrograms of LH-RH was significantly reduced with the increase in LH-pf. Pituitary response to 100 micrograms of LH-RH in women with hyperprolactinemia was maintained despite low LH-pf. These results suggest that the analysis of pulsatile LH secretion is very helpful in evaluating hypothalamic-pituitary function in amenorrheic women.