FOLLICLE-STIMULATING-HORMONE IS SECRETED MORE IRREGULARLY THAN LUTEINIZING-HORMONE IN BOTH HUMANS AND SHEEP

Recently introduced statistical tools capable of discerning difference s between the pattern of luteinizing hormone (LH) secretion and that o f follicle-stimulating hormone (FSH) could be valuable in understandin g ovulation and menopause, and ultimately in making diagnostic decisio ns and treating infertility and polycystic ovary syndrome, We assessed the validity and scope of the hypothesis that FSH is secreted more ir regularly than LH in ewes and fertile women, We compared secretory irr egularity of LH to that of FSH in both ovariectomized ewes (n = 7) and women of proven fertility (n = 5) during the follicular and luteal ph ases of their reproductive cycles, Tn each sheep, time series from bot h hypophyseal portal blood (HPB) and peripheral blood were evaluated i n 72 samples obtained every 5 min; in each human, both luteal and foll icular periods were studied in 192 samples obtained every 7.5 min, To quantify serial irregularity, we used approximate entropy (ApEn), a sc ale-and model-independent statistic. FSH secretion was consistently mo re irregular than that of LH in each subject, For sheep HPB, ApEn(FSH) = 1.415 +/- 0.097 was larger than ApEn(LH) = 0.822 +/- 0.213, P < 0.0 001 (mean +/- SD, paired t test), This difference persisted peripheral ly: ApEn(FSH,,) = 1.431 +/- 0.101 > ApEn(LHper) = 1.252 +/- 0.086, P = 0.024. In women, ApEn(FSH)= 1.467 +/- 0.217 > ApEn(LH) = 0.923 +/- 0. 305, P < 0.0001, ApEn(FSH) > ApEn(LH) in 100% of women (peripheral) an d sheep HPB. Secretion during the follicular phase was more irregular than during the luteal phase for both FSH and LH (P < 0.01), LH mean l evel secretion showed a wake/sleep difference in women, P < 0.005, wit h higher values awake, The consistency and statistical significance of these findings suggest that this LH/FSH difference may be broadly bas ed within higher mammals, Ranges of normative and abnormal regularity values of LH, FSH, and their difference can be used in a number of set tings, both (currently) research and (potentially ultimately) clinical milieus.