Altered luteinizing hormone pulse frequency in early follicular phase of the menstrual cycle with luteal phase defect patients in women.

OBJECTIVE

To delineate the relationship between the pulsatile gonadotropin inputs in early follicular phase of the menstrual cycle and the P secretions by the corpus luteum in women.

DESIGN

For measuring pulsatile release of gonadotropin, blood samples were drawn every 15 minutes for 24 hours in the early follicular phase. Daily blood samples were drawn for LH, FSH, E2, and P.

SETTING

The reproductive endocrine unit of a university hospital.

PATIENTS

Fourteen patients with luteal phase defect (LPD) and 12 normally cycling women.

RESULTS

The length of follicular phase in LPD was significantly shorter than that of women with normal cycles. There were significant differences in LH pulsatile secretions and amplitudes in LPD patients when compared with those of women with normal cycles. Basal E2, PRL, and preovulatory E2 concentrations were not different between the two groups whereas the peak of P secretions in luteal phase was significantly decreased in LPD.

CONCLUSIONS

These data suggest that LPD may result from the altered LH pulse frequency in early follicular phase of the menstrual cycle. Whether this increased LH pulse frequency results from an intrinsic disease of the pulse oscillator or to some event in the preceding cycle remains unknown. It is tempting to speculate that an increased LH pulsatile secretion in the early follicular phase of menstrual cycles in patients with LPD may down-regulate the LH secretion at midcycle, thereby lowering the LH surge, which in turn reduces the P secretion in luteal phase.