Polycystic ovarian syndrome explained

Not a lot is known about the causes of polycystic ovarian syndrome (PCOS), but its symptoms are fairly telltale and include obesity, hirsutism (the medical name for excess face or body hair) acne and infertility. It's estimated that PCOS affects over five per cent of women in the UK and it has recently been associated with long-term risks of diabetes, heart disease and endometrial cancer.

As PCOS's name suggests, the syndrome is often (but not always) accompanied by ovaries enlarged with multiple small cysts. During the normal ovulation process, a hormone called follicle stimulating hormone (FSH) causes the release of an egg from an ovarian follicle, which then bursts from the follicle in the middle of the woman's menstrual cycle in response to another hormone, luteinising hormone (LH).

It is thought that in polycystic ovarian syndrome, male hormones or androgens somehow interfere with the levels of FSH and LH. This causes lots of follicles to form and no egg to be released from these follicles - whose appearance via an ultrasound is sometimes likened to a string of pearls - which forms the cysts observed in PCOS. >What causes it?
The exact cause of PCOS is unknown, although there is research into possible hereditary or genetic links. It is believed that the high levels of androgens appear as a result of abnormally high insulin levels. Produced by the pancreas, insulin is the hormone that regulates blood sugar levels. For some reason, in those women with PCOS, the cells around the body seem to become 'resistant' to insulin and so the pancreas makes more and more.

These high insulin levels send signals to the body to make more androgens, the so-called 'male' hormones, which include testosterone, and in turn causes multiple ovarian cysts, as well as obesity, acne and hirsutism.

When does it start?
For many, the syndrome starts around puberty, the first sign being irregular or absent periods. For others, PCOS symptoms may first become noticeable in the early 20s when acne or excess hair develops. The hormonal abnormalities of PCOS are possible even for women whose ovaries have been removed because androgens can be produced elsewhere in the body.