Which among the following is TRUE about MIRENA?
**Core Concept**
MIRENA is a levonorgestrel-releasing intrauterine system (LNG-IUS), a type of hormonal contraceptive device used to prevent pregnancy and treat heavy menstrual bleeding. It releases a controlled amount of the progestin levonorgestrel, which works by thickening the cervical mucus and thinning the uterine lining.
**Why the Correct Answer is Right**
The correct answer is related to the mechanism of action of MIRENA. The levonorgestrel released by the device works by binding to the progesterone receptor in the endometrium, which leads to a decrease in the proliferation of endometrial cells and an increase in the apoptosis of these cells. This results in a thinner endometrial lining, making it less receptive to implantation of a fertilized egg. Additionally, the levonorgestrel thickens the cervical mucus, making it more difficult for sperm to reach the egg.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because MIRENA does not work by increasing the production of follicle-stimulating hormone (FSH) or luteinizing hormone (LH).
**Option B:** This option is incorrect because MIRENA is not a type of estrogen-only contraceptive.
**Option C:** This option is incorrect because MIRENA is not a type of copper intrauterine device (IUD).
**Clinical Pearl / High-Yield Fact**
It's essential to note that MIRENA is also used off-label to treat symptoms of endometriosis, such as pelvic pain and dysmenorrhea.
**Correct Answer:**
MIRENA works by thickening the cervical mucus and thinning the uterine lining.