Dynamic testing of hypothalamic-pituitary function in abnormalities of ovulation

Increasing LH pulsatility in women with hypothalamic amenorrhoea using intravenous infusion of Kisspeptin-54

BACKGROUND

Hypothalamic amenorrhea (HA) is the one of the most common causes of period loss in women of reproductive age and is associated with deficient LH pulsatility. High-dose kisspeptin-54 acutely stimulates LH secretion in women with HA, but chronic administration causes desensitization. GnRH has paradoxical effects on reproductive activity; we therefore hypothesized that a dose-dependent therapeutic window exists within which kisspeptin treatment restores the GnRH/LH pulsatility in women with HA.

AIM

The aim of the study was to determine whether constant iv infusion of kisspeptin-54 temporarily increases pulsatile LH secretion in women with HA.

METHODS

Five patients with HA each underwent six assessments of LH pulsatility. Single-blinded continuous iv infusion of vehicle or kisspeptin-54 (0.01, 0.03, 0.10, 0.30, or 1.00 nmol/kg/h) was administered. The LH pulses were detected using blinded deconvolution.

RESULTS

Kisspeptin increased LH pulsatility in all patients with HA, with peak responses observed at different doses in each patient. The mean peak number of pulses during infusion of kisspeptin-54 was 3-fold higher when compared with vehicle (number of LH pulses per 8 h: 1.6 ± 0.4, vehicle; 5.0 ± 0.5, kisspeptin-54, P < .01 vs vehicle). The mean peak LH pulse secretory mass during kisspeptin-54 was 6-fold higher when compared with vehicle (LH pulse secretory mass in international units per liter: 3.92 ± 2.31, vehicle; 23.44 ± 12.59, kisspeptin-54; P < .05 vs vehicle).

CONCLUSIONS

Kisspeptin-54 infusion temporarily increases LH pulsatility in women with HA. Furthermore, we have determined the dose range within which kisspeptin-54 treatment increases basal and pulsatile LH secretion in women with HA. This work provides a basis for studying the potential of kisspeptin-based therapies to treat women with HA.

Prognostic assessment of female fecundity

A clomiphene citrate (CC) challenge test was used to prospectively assess future fertility potential in 51 women aged 35 or more with unexplained infertility. Baseline (day 2-3 of the menstrual cycle) and response levels (day 9-11) of follicle stimulating hormone (FSH), luteinising hormone (LH), and 17-beta oestradiol were measured before and after administration of 100 mg clomiphene on days 5-9 of the menstrual cycle. Although all the women had a normal baseline FSH, 18 had an exaggerated FSH response of 26 mIU/ml or more (over 2 standard deviations above control values); this was regarded as a diminished ovarian reserve (DOR). In the DOR group mean response FSH was 38.9 mIU/ml (SD 13.8) and in 33 women with adequate ovarian reserve (AOR) it was 11.5 (4.9) mIU/ml (p less than 0.0001). In the DOR group 1 of 18 patients and in the AOR group 14 of 33 (42%) conceived (p less than 0.05). It is suggested that despite apparently normal ovulatory cycles, the DOR group has a compromised follicular apparatus. Disparity between normal oestradiol secretory capacity of the granulosa and diminished capacity to secrete inhibin could explain the inappropriately high FSH levels in response to the CC challenge.

The action of clomiphene in stress-induced amenorrhea

Seven women with stress-induced amenorrhea were challenged with metoclopramide, 10 mg intravenously, before and at the end of a course of clomiphene. Initial testing with luteinizing hormone releasing hormone demonstrated that all subjects had the capacity to release luteinizing hormone (LH), but in response to metoclopramide there was no increase in the levels of LH. This lack of response did not change after 5 days of clomiphene, although basal levels of LH and estradiol increased significantly. The pattern of response of prolactin to metoclopramide did not change after clomiphene. These results suggest that there is no significant dopamine-mediated inhibition of release of luteinizing hormone releasing hormone in women with stress-induced amenorrhea. The administration of clomiphene to these women does not appear primarily to alter hypothalamic dopaminergic activity.