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Also known as: Polycystic Ovarian Syndrome; Stein-Leventhal Syndrome

What is polycystic ovarian syndrome?

Polycystic ovarian syndrome (PCOS) is one of the leading causes of infertility, affecting 6-8% of women worldwide of childbearing age. Although the underlying cause is not well understood, PCOS is generally characterized by numerous fluid-filled sacs (cysts) on the ovaries, an excess production of androgens, absence of (amenorrhea) or prolonged menstrual periods (menometrorrhagia), absence of ovulation (ovaries do not release eggs (anovulation)), excess hair growth, obesity, and a varying degree of insulin resistance.

Androgens are normally produced in small amounts by a woman's ovaries and adrenal glands. Even a slight overproduction of male hormones, such as testosterone, can lead to symptoms such as hirsutism, acne, and in extreme cases, virilization.

Normal menstruation is regulated by hormones released by the pituitary gland and the ovaries. In PCOS, the pituitary releases increased levels of leuteinizing hormone (LH) and the ovaries produce greater amounts of androgens. These hormonal imbalances affect the monthly menstrual cycle, resulting in irregular periods. Thus, egg release is sporadic or even absent, often resulting in infertility problems.

With PCOS, both ovaries tend to be enlarged, as much as three times their normal size. In as many as 90% of women with PCOS, an ultrasound of the ovaries will reveal cysts, small immature egg-bearing follicles, fluid-filled follicles , that can be seen on the surface of the ovary. These ovarian cysts are often lined up to form the appearance of a "pearl necklace."

When an egg is not released and a woman is not menstruating, sufficient progesterone is not produced. Insufficient progesterone causes a hormonal imbalance in which estrogen goes "unopposed." This 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 miscarriage.

Although the cause of PCOS is not well understood, some think that insulin resistance may be a key factor. Insulin is vital for the transportation and storage of glucose at the cellular level; it helps regulate blood glucose levels and has a role in carbohydrate and lipid metabolism. When there is resistance to insulin's use at the cellular level, the body tries to compensate by making even more insulin in the blood (hyperinsulinemia). Some believe that hyperinsulinemia may be at least one cause for increased production of androgens by the ovaries.

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

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