In most cases, causes of endometrial hyperplasia cases are high levels of estrogen without progesterone. If a woman does not ovulate, progesterone does not get made and the lining is not shed. Consequently, a woman’s endometrium may continued growing in response to estrogen, and the cells that make up the uterine lining may gather together and become abnormal.
This condition usually happens after menopause, when ovulation stops and the woman’s body is no longer making progesterone, as well as in perimenopause, the period leading up to menopause when ovulation may occur irregularly.
Some risk factors for endometrial hyperplasia include:
- Estrogen replacement therapy, or taking high doses of estrogen after menopause (among women who have not had a hysterectomy)
- Using medications that act like estrogen
- Having irregular periods, especially those associated with polycystic ovary syndrome or infertility
- Personal history of conditions such as polycystic ovary syndrome, diabetes mellitus, gallbladder disease or thyroid disease
- Family history of uterine, colon or ovarian cancer
- Being Caucasian and over the age of 35
- Cigarette smoking
- Never having been pregnant
- Entering menopause at an older age
- Starting menstruation at an early age
In addition, a certain type of ovarian tumor called a granulosa cell tumor can create estrogen, which in turn can lead to endometrial hyperplasia or even endometrial cancer.