The effect of treatment with a low-dose progestagen (Lynestrenol) on hormonal cytology

The effect of continuous, low-dose progestagen therapy on endogenous oestrogen production and ovulation in women, was investigated in terms of vaginal cytology. The phase contrast method was used to establish the karyopknotic index from 482 smears from patients using lynestrenol 0.5 mg for oral contraception. The results are presented as the mean of karyopyknotic indices, with standard deviation and standard error of the mean, scored over each three day period of the menstrual cycle, and, in the case of delayed menstruation, over longer periods throughout the protracted cycle. Graphically, the results are shown as average levels compared to controls. Our results show that in patients who have used the preparation for a maximum of three months, cyclic oestrogen production varies only slightly, the mean being within the lower limit of normal and suggesting FSH suppression. In patients who use the preparation for longer periods, the karyopyknotic index becomes similar throughout the cycle to that of controls, being clearly biphasic and generally suggestive of ovulation. In the first group, delayed menstruation seems to be caused mainly by transient FSH suppression. When it occurs in the group treated over a longer period, the disorder appears to be caused by a normo- or hyperoestrogenic, anovulatory condition, due initially to LH suppression with FSH supression setting in later, if the disorder persists longer.