POI is when the ovaries are not working normally. The hormones that are naturally made by the ovaries (estrogen, progesterone, and testosterone) are no longer being produced in normal amounts, and the ovaries don't release eggs or release them just once in a while.

Girls with POI may have one or more of the following symptoms:
-- Follicle Stimulating Hormone Deficiency
-- Lack of breast development during puberty
-- Lack of menstrual periods or irregular periods
-- Small breasts or decrease in breast size
-- Hot flashes
-- Lack of normal vaginal discharge
-- Mood swings
-- Trouble sleeping

Why is the FSH level high?
In menstruating women, the pituitary gland in the brain can sense if the ovaries are not making the right amount of estrogen. If a woman is not getting her period, and there is no estrogen being made, the pituitary gland in the brain will release follicle-stimulating hormone (FSH). This hormone sends a signal to the ovaries to make estrogen and stimulates the growth of a "follicle," which will later release an egg. When the ovary responds, it also sends a signal to tell the pituitary to stop producing FSH, so the FSH level in the blood decreases.

In young women with POI, the ovaries do not function normally, so they cannot respond to the FSH in the normal way. Thus, there is no signal to the pituitary to stop its production of FSH. Instead, it keeps trying to get the ovaries to respond by producing more and more FSH. Thus, in women with POI, the level is FSH is high.

How is POI treated?
The treatment for POI is to replace the hormones that your body is not making. This type of treatment is called hormone replacement therapy, or HRT. The hormones that need to be replaced are estrogen and progesterone. These hormones are needed for breast development, menstrual periods, and healthy bones.

There are many different types of HRT, including the hormonal patch, the vaginal ring, hormone pills, or shots. The hormone patch or "transdermal estrogen" provides estrogen levels similar to what the ovaries normally make. The patch releases estrogen and is applied to the skin once or twice a week. Progesterone can be taken as a pill or as part of a patch. It’s taken 10-14 days a month. Estrogen comes in pills just for HRT or in birth control pills, but the dose may be higher than needed just for replacement. With birth control pills or vaginal rings, you take estrogen and progesterone every day. Rarely, women with POI have become pregnant while on HRT.