Polycystic ovarian syndrome (PCOS), which used to be called Stein-Leventhal syndrome in its most severe form, 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 is certainly a leading cause of infertility. Although the underlying cause is not well understood, PCOS is generally characterised by an excess production of androgens (male hormones - usually testosterone), lack of ovulation i.e. anovulation (the egg is not released by the ovary) and absence of menstrual periods (amenorrhoea), and by a varying degree of insulin resistance. The ovaries usually have many fluid-filled sacs (cysts) hence the name of the condition.
Androgens are normally created in small amounts by a woman's ovaries and adrenal glands. Even a slight overproduction can lead to symptoms such as hirsutism and acne. In extreme cases, they can lead to virilization.
There is frequently increased secretion of luteinising hormone (LH) from the pituitary gland and all these 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 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 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 acts "unopposed." This can lead to an overgrowth of the lining of the uterus (endometrial hyperplasia) and increases 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 lipid dysfunction. 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.