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Polycystic Ovary Syndrome

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Also known as: PCOS; Stein-Leventhal Syndrome

What is polycystic ovary syndrome?

Thumbnail diagram of the cervixPolycystic ovary syndrome (PCOS) is a condition associated with hormone imbalances that affects women. Though the underlying cause of PCOS is not known or well understood, it is believed that an imbalance of sex hormones and resistance to the effects of the hormone insulin are the main problems. These problems result in a characteristic group of signs, symptoms and complications such as excess facial and body hair, irregular menstrual periods, infertility, and insulin resistance.

PCOS is the most common hormone disorder in women and one of the leading causes of infertility, affecting roughly 5-10% of women of childbearing age. The condition can affect girls as young as 11. Because the signs and symptoms often seem unrelated and the diagnostic criteria are not yet clear, most women are not diagnosed until they are in their 20's or 30's. It appears to run in families. Women with sisters who have PCOS are twice as likely to have the condition.

Though the diagnostic criteria are not yet clear, women usually have at least two of the following to be diagnosed with PCOS:

  • Overproduction of male hormones (androgens)
  • No release of eggs from the ovaries (no ovulation)
  • Polycystic ovaries—polycystic literally means "many cysts." A main feature of PCOS is that eggs are not released from a woman's ovaries. Instead, fluid builds up around the eggs, forming sacs (cysts). Though this feature is the origin of the name of the disorder, not all women diagnosed with PCOS have polycystic ovaries.

Hormone Imbalance
Though called "male hormones," androgens are normally produced in small amounts by a woman's ovaries and adrenal glands. However, when there is even a slight overproduction of male hormones, such as testosterone, a woman can experience signs and symptoms such as excess facial and body hair (hirsutism), acne, and weight gain.

These hormonal imbalances can also disrupt a woman's monthly menstrual cycle and cause irregular periods. When this happens, ovulation or egg release may be inhibited. If ovulation does not occur, a woman cannot conceive and she experiences fertility problems.

In PCOS, both ovaries tend to be enlarged, as much as three times their normal size. Eggs that do not mature fully are not released during ovulation and the immature eggs remain in the ovary as pearl-sized, fluid filled sacs. Over the course of time, many cysts may develop into what looks like a string of beads when viewed through ultrasound imaging. In as many as 90% of women with PCOS, an ultrasound of the ovaries will reveal cysts.

When a woman is not menstruating or ovulating, an insufficient amount of the hormone progesterone is produced. This hormonal imbalance can lead to an overgrowth of the lining of the uterus (endometrial hyperplasia) and can increase a woman's risk of developing endometrial cancer. Women with PCOS who do ovulate and become pregnant tend to have an increased risk of complications such as miscarriage.

Insulin Resistance
It is thought that insulin resistance may be a key factor in PCOS. Insulin helps transport glucose into the body's cells. where it is needed for energy production. When there is resistance to insulin's effect, the body tries to compensate by making even more insulin and releasing it in the blood (hyperinsulinemia). Some believe that too much insulin may cause the ovaries to increase androgen production, which in turn causes the symptoms associated with PCOS.

Most women with PCOS have some degree of insulin resistance, weight gain, and abnormal blood lipid levels. However, insulin resistance tends to be even more pronounced in women who are obese and do not ovulate. These conditions put those with PCOS at a higher risk of developing type 2 diabetes, high blood pressure (hypertension), and cardiovascular disease.

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