Reduced frequency of luteinizing hormone pulses in women with weight loss-related amenorrhoea and multifollicular ovaries.

We have studied pulsatile secretion of LH in 10 women with secondary amenorrhoea and multifollicular ovaries (MFO). This group of patients have a history of mild to moderate, or partially recovered weight loss. They have normal basal LH concentrations but evidence of oestrogen deficiency suggesting a hypothalamic abnormality of gonadotrophin regulation. The results of gonadotrophin pulse analysis were compared with those in normal women during the early follicular phase of the cycle. The mean LH concentration during the 8 h study (5.0 +/- 0.9 [SD] U/l) was not significantly different from that in normal women (5.7 +/- 2.5). There was no difference between the groups in mean LH pulse amplitude (2.1 +/- 0.5 in MFO; 2.2 +/- 1.3 in normal women). The frequency of LH pulses was, however, significantly lower in women with MFO (2.8 +/- 1.6 vs 4.8 +/- 1.5, P less than 0.05). Two women with MFO had LH pulses of normal frequency. One subsequently developed a normal pattern of ovarian follicles. The other showed a sleep-related rise in LH concentrations during a 24 h profile which was similar to the pattern of gonadotrophin secretion normally observed during late puberty. These results show that women with MFO have a hypothalamic disturbance of gonadotrophin regulation with slowing of LH pulses without a diminution of pulse amplitude.