Alvarez F, Brache V, Tejada A S, Faúndes A
Contraception. 1986 Feb;33(2):111-9. doi: 10.1016/0010-7824(86)90077-6.
FSH, LH, estradiol and progesterone were serially assayed during 8 cycles of six subjects using six subdermal implants releasing levonorgestrel (NORPLANT) for a period of 2 to 6 years. All 8 cycles studied had a very low LH peak and a low or nonexistent FSH peak as compared to 8 control cycles. The mean LH peak for NORPLANT users was 33.9 mIU/ml as compared to 142 mIU/ml in the control group; and FSH was 13.0 mIU/ml as compared to 31.3 mIU/ml in controls. A subsequent rise in progesterone was observed in the 8 cycles studied, but the mean mid-luteal levels were significantly lower than in controls (9.0 ng/ml vs. 15.6 ng/ml). No differences were observed in the estradiol curve. Two of the subjects using NORPLANT had a laparotomy performed on days 17 and 20 of the cycle, for surgical sterilization purposes. A distinctive corpus luteum with a stigma was observed. Our results indicate that women under prolonged use of NORPLANT do not have normal endocrine cycles, even though they may ovulate. It is doubtful however, that these ovulatory cycles can be fertile under the abnormal endocrine conditions found in our subjects. In addition to the possible effect of luteal insufficiency, the normal maturation of the oocyte may be impaired.
