The levonorgestrel intrauterine system (LNG IUS), a steroid-releasing intrauterine system, is a T-shaped device that releases levonorgestrel directly into the uterine cavity at an initial rate of 20 μg per day. The contraceptive and therapeutic benefits of the LNG IUS stem primarily from its local effects. The local hormone delivery causes high levonorgestrel levels in the endometrial tissue but low levels in the systemic circulation. This leads to strong endometrial suppression and, in many cases, a dramatic reduction in menstrual blood loss. The high contraceptive efficacy is well documented through extensive international clinical research. This review article provides an overview of the LNG IUS and addresses the following topics: mechanisms of action, contraceptive efficacy, changes in bleeding patterns, principal safety issues, potential noncontraceptive benefits, and implications for women’s reproductive health.
Obstetricians & Gynecologists, Family Physicians
After completion of this article, the reader should be able to explain that the levonorgestrel intrauterine system (LNG IUS) has contraceptive and therapeutic benefits, identify the main site of action as the endometrium, and to recall that the safety of the system has been validated over time.
Leon Speroff Professor of Obstetrics and Gynecology, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon
Chief Editor’s Note: This article is the 25th of 36 that will be published in 2005 for which a total of up to 36 Catgory 1 CME credits can be earned. Instructions for how credits can be earned appear on the last page of the Table of Contents. This CME activity is supported by an unrestricted educational grant from Procter & Gamble.
Dr. Jensen is/was the recipient of research/grant funding from, was a consultant to, and is/was a member of the speakers bureau of Berlex Laboratories.
Wolters Kluwer Health has identified and resolved all faculty conflicts of interest regarding this educational activity.
The author has disclosed that the LNG IUS (Mirena) has not been approved by the U.S. Food and Drug Administration for use in the treatment of menorrhagia, anemia, hormone replacement therapy, uterine myomas, endometriosis, or adenomyosis. Please consult product labeling for the approved usage of this drug or device.
Reprint requests to: Jeffrey T. Jensen, MD, MPH, Leon Speroff Professor of Obstetrics and Gynecology, Department of Obstetrics and Gynecology, UHN-70, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239. E-mail: firstname.lastname@example.org.