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What is it?

Polycystic ovarian syndrome (PCOS), which was originally called Stein-Leventhal syndrome, is a common condition, affecting 5 to 10% of women of childbearing age. The disorder is probably the most common hormonal abnormality in women of reproductive age and one of the causes of infertility. It also seems to run in families. Although the underlying cause is not well understood, it is believed that an imbalance of sex hormones and resistance to the effects of the hormone insulin are the main problems. It is generally characterised by an excess production of androgens (male hormones - usually testosterone), anovulation (the egg is not released by the ovary) and menstrual disturbances, infertility and by a varying degree of insulin resistance.

Androgens are normally formed in small amounts by a woman's ovaries and adrenal glands. Even a slight overproduction can lead to symptoms such as hirsutism (increased body hair) and acne. In extreme cases, they can lead to virilisation (masculinisation).

Hormone imbalances also affect the menstrual cycle in PCOS, causing infertility problems. Most women with this condition do not have regular monthly periods. Often they have chronic anovulation and amenorrhoea, but they may also experience irregular periods and uterine bleeding. With PCOS, both ovaries tend to be enlarged as much as 3 times their normal size. In 90% of women with PCOS, an ultrasound of the ovaries will reveal cysts - small immature egg-bearing follicles, fluid-filled spaces - 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 the egg is not released and a woman is not menstruating, sufficient progesterone is not produced. This leads to a hormonal imbalance in which oestrogen goes "unopposed." This can lead to an overgrowth of the lining of the uterus (endometrial hyperplasia) and may 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 more. This leads to hyperinsulinaemia, elevated levels of insulin in the blood. Some believe that hyperinsulinaemia may be at least one cause for an increased production of androgens by the ovaries.

Most women with PCOS have varying degrees of insulin resistance, obesity, and blood lipid abnormalities. Insulin resistance tends to be 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 and cardiovascular disease.

Last Review Date: July 1, 2018

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