Ovarian endocrine function through five years of continuous treatment with NORPLANT subdermal contraceptive implants.

ABSTRACT

PIP: Ovarian endocrine function was assessed in 88 women using NORPLANT subdermal implants during different periods of use and in a control group of 15 women using non-hormonal contraception. Blood samples for estradiol (E) and progesterone (P) assays were obtained twice a week for 5 consecutive weeks. 3 distinct E patterns were observed; one was characterized by fluctuating levels within a normal range (20 to 400 pg/ml), a 2nd pattern corresponded to continuous low E levels (below 75 pg/ml in the 10 samples) and the 3rd was characterized by high broad estradiol peaks reaching over 400 pg/ml. The proportion of sampling runs characterized by normal fluctuating levels increased from 38% in the first 2 years of use to 80% during the 5th year of use. Low E profile was only observed during the first 2 years of use (27%) and in only 1 case at the beginning of the 3rd year of use (5%). The % of cycles with high broad estradiol peaks remained between 20-40% without a clear tendency to change in either direction with duration of use. 33% of the observed sampling runs had luteal activity (p 3 ng/ml). The proportion of runs with luteal activity increased from 14% during the first 2 years of use to 40% during the 3rd and 4th, and 60% during the 5th year of use. All control subjects had luteal activity. The mean highest progesterone level was lower in the NORPLANT runs (8.7 + or - 3.9 ng/ml) as compared to the controls (11.3 + or - 3.8 ng/ml). NORPLANT sampling runs with luteal activity had normal fluctuating E levels with only 1 exception. However, not all cycles with normal E levels showed luteal activity. On the other hand, all runs with low E levels or high broad E peaks were without luteal activity. In summary, women using continuous low-dose levonorgestrel contraception through NORPLANT subdermal implants, have a variable degree of ovarian activity as compared with the more complete depression of ovarian function observed among pill or injectables' users. Ovarian activity becomes closer to normal during the 3rd through 5th year of use. (Author's).