ALTERED LUTEINIZING-HORMONE PULSE FREQUENCY IN EARLY FOLLICULAR PHASEOF THE MENSTRUAL-CYCLE WITH LUTEAL-PHASE DEFECT PATIENTS IN WOMEN

Objective: To delineate the relationship between the pulsatile gonadot ropin inputs in early follicular phase of the menstrual cycle and the P secretions by the corpus luteum in women. Design: For measuring puls atile release of gonadotropin, blood samples were drawn every 15 minut es for 24 hours in the early follicular phase. Daily blood samples wer e drawn for LH, FSH, E2, and P. Setting: The reproductive endocrine un it of a university hospital. Patients: Fourteen patients with luteal p hase defect (LPD) and 12 normally cycling women. Results: The length o f follicular phase in LPD was significantly shorter than that of women with normal cycles. There were significant differences in LH pulsatil e secretions and amplitudes in LPD patients when compared with those o f women with normal cycles. Basal E2, PRL, and preovulatory E2 concent rations were not different between the two groups whereas the peak of P secretions in luteal phase was significantly decreased in LPD. Concl usions: These data suggest that LPD may result from the altered LH pul se frequency in early follicular phase of the menstrual cycle. Whether this increased LH pulse frequency results from an intrinsic disease o f the pulse oscillator or to some event in the preceding cycle remains unknown. It is tempting to speculate that an increased LH pulsatile s ecretion in the early follicular phase of menstrual cycles in patients with LPD may down-regulate the LH secretion at midcycle, thereby lowe ring the LH surge, which in turn reduces the P secretion in luteal pha se.