False statement about Mirena is
**Core Concept**
Mirena is a levonorgestrel-releasing intrauterine system (LNG-IUS) used for contraception and treatment of heavy menstrual bleeding. It releases a controlled amount of the progestin levonorgestrel, which exerts local effects on the endometrium and systemic effects through the bloodstream.
**Why the Correct Answer is Right**
The correct answer is related to the mechanism of action of Mirena. Levonorgestrel in Mirena causes endometrial atrophy by downregulating the expression of genes involved in cell proliferation, such as **prostaglandin H synthase 2** (PGHS2) and **cytokeratin 10** (KRT10). This leads to a decrease in menstrual blood loss and an increase in the thickness of the endometrium. Additionally, the local release of levonorgestrel in the uterus prevents implantation of the fertilized ovum by altering the **endometrial receptivity**.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because Mirena is not a type of estrogen-only contraceptive. While Mirena contains a small amount of estrogen (0.5 mg norethisterone), its primary mechanism is through the release of levonorgestrel.
* **Option B:** This option is incorrect because Mirena is actually a progestin-only contraceptive. It is not a combination of estrogen and progestin.
* **Option C:** This option is incorrect because Mirena is not associated with an increased risk of endometrial cancer. In fact, the local release of levonorgestrel in the uterus may even reduce the risk of endometrial cancer.
**Clinical Pearl / High-Yield Fact**
Mirena is a highly effective form of contraception, with a failure rate of less than 1% when used correctly. It is also a useful treatment for heavy menstrual bleeding, with a significant reduction in menstrual blood loss and improvement in quality of life.
**Correct Answer:** None