Content Reviewers:Yifan Xiao, MD
With endometrial hyperplasia, endometrial refers to the endometrium, which is the inner lining of the uterus, and hyperplasia means increased growth, so endometrial hyperplasia means excessive growth of the inner lining of the uterus.
The endometrium has two layers, an inner functional layer made up mainly of glands and supporting connective tissue, called stroma, and an outer thin basal layer which regenerates the overlying functional layer after each menstrual cycle.
Each follicle consists of an oocyte, which is the female germ cell, surrounded by an outer layer made up of theca cells, which secrete androgens, also known as the male hormones, and an inner layer made up of granulosa cells, which secrete estrogen.
This is also called the proliferative phase because it’s when the lining of the endometrium grows.
At the same time, it causes the glands to produce secretions that acts as nutrients for any developing embryo.
This leads to excessive growth of endometrial glands relative to stroma; meaning a high gland-to-stroma ratio.
The same goes for females who have never given birth, also called nulliparous, who are at a higher risk than those who have been pregnant. This is because follicular growth and their estrogen secretion is inhibited during pregnancy. Thus people who have been pregnant will have fewer menstrual cycles in their lifetime compared to someone who hasn’t
Also, we have drugs that can cause endometrial hyperplasia, such as estrogen-only hormone replacement therapy, usually taken by postmenopausal females to relieve menopause symptoms, such as hot flashes and vaginal dryness.
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