CHARACTERISTICS OF LUTEINIZING-HORMONE SECRETION IN YOUNGER VERSUS OLDER PREMENOPAUSAL WOMEN

OBJECTIVES: The objectives of this study were to document specific att ributes of pulsatile luteinizing hormone secretion in middle-aged wome n before discernible alterations in their menstrual cycles and to comp are the results to corresponding data obtained in younger women. STUDY DESIGN: After documenting normal cycle length, biphasic basal body te mperatures, and normal midluteal progesterone in younger and middle-ag ed women during an initial cycle, daily blood samples and samples with drawn at IO-minute intervals for 8 hours during the midfollicular phas e were obtained during a subsequent cycle. RESULTS: Assessment of lute inizing hormone pulses with the pulse detection algorithm Cluster demo nstrated a prolonged interpulse interval and increased pulse width in the older women. Assessment of luteinizing hormone secretory bursts an d half-life with the deconvolution analysis procedure demonstrated a p rolonged interburst interval and half-life in the older women. Apprais al of approximate entropy revealed greater orderliness of luteinizing hormone release in the older women. CONCLUSIONS: Middle-aged women exh ibit alterations in hypothalamic-pituitary function that may account i n part for age-related changes in reproductive potential.