Polycystic ovary syndrome, or PCOS, is the most common endocrine disorder in women of reproductive age. The syndrome is named after the characteristic cysts which may form on the ovaries, though it is important to note that this is a sign and not the underlying cause of the disorder.Women with PCOS may experience irregular menstrual periods, heavy periods, excess hair, acne, pelvic pain, difficulty getting pregnant, and patches of thick, darker, velvety skin. The primary characteristics of this syndrome include: hyperandrogenism, anovulation, insulin resistance, and neuroendocrine disruption.A review of the international evidence found that the prevalence of PCOS could be as high as 26% among some populations, though ranges between 4% and 18% are reported for general populations. Despite its high prevalence, the exact cause of PCOS remains uncertain and there is no known cure. Definition
Two definitions are commonly used:

NIHIn 1990 a consensus workshop sponsored by the NIH/NICHD suggested that a person has PCOS if they have all of the following:oligoovulation
signs of androgen excess (clinical or biochemical)
exclusion of other disorders that can result in menstrual irregularity and hyperandrogenismRotterdamIn 2003 a consensus workshop sponsored by ESHRE/ASRM in Rotterdam indicated PCOS to be present if any 2 out of 3 criteria are met, in the absence of other entities that might cause these findings:
oligoovulation and/or anovulation
excess androgen activity
polycystic ovaries (by gynecologic ultrasound)The Rotterdam definition is wider, including many more women, the most notable ones being women without androgen excess.
Elevated insulin levels have been helpful to predict response to medication and may indicate women needing higher doses of metformin or the use of a second medication to significantly lower insulin levels. Elevated blood sugar and insulin values do not predict who responds to an insulin-lowering medication, low-glycemic diet, and exercise. Many women with normal levels may benefit from combination therapy. A hypoglycemic response in which the two-hour insulin level is higher and the blood sugar lower than fasting is consistent with insulin resistance. A mathematical derivation known as the HOMAI, calculated from the fasting values in glucose and insulin concentrations, allows a direct and moderately accurate measure of insulin sensitivity (glucose-level x insulin-level/22.5). Management
The primary treatments for PCOS include lifestyle changes and use of medications.Goals of treatment may be considered under four categories:

Lowering of insulin resistance
Restoration of fertility
Treatment of hirsutism or acne
Restoration of regular menstruation, and prevention of endometrial hyperplasia and endometrial cancerIn each of these areas, there is considerable debate as to the optimal treatment. One of the major factors undelying the debate is the lack of large-scale clinical trials comparing different treatments. Smaller trials tend to be less reliable and hence may produce conflicting results. General interventions that help to reduce weight or insulin resistance can be beneficial for all these aims, because they address what is believed to be the underlying cause. As PCOS appears to cause significant emotional distress, appropriate support may be useful.