LH pulse frequency in relation to positive oestrogen-gonadotrophin feedback in amenorrhoea.

The relationship between the pattern of pulsatile LH release and the response to oestrogen provocation was studied in twenty amenorrhoeic or oligomenorrhoeic subjects. In 12 subjects with positive oestrogen-gonadotrophin feedback a definite pulsatile pattern of LH release was demonstrated with a pulse frequency of 60--80 min and an increase from nadir to peak ranging between 30 and 58%. The mean basal LH concentration was significantly higher in this group (P less than 0.001). Of eight subjects who had absence of positive feedback, five showed infrequent pulses, 1--2 during the four-hour period. These were of low amplitude and with a percentage increase of 45--70 from nadir to peak. The remaining three did not have a pulsatile pattern of LH release. Positive feedback, as demonstrated by an oestrogen provocation test was thus found only in patient having 3 or more LH pulses in the 4 h study period; an LH pulse frequency similar to that in the early follicular phase in regularly menstruating women.