Polycystic ovarian syndrome (PCOS) is a disorder that affects the endocrine system. With PCOS, the normal hormone cycles are disrupted, causing interference with a woman’s ovulation cycle. Hormones are responsible for various functions throughout the body, including regulating a woman’s reproductive functions (e.g., normal development of eggs in the ovaries). It is not completely understood why or how the hormone cycles are disrupted by PCOS.

PCOS is a syndrome rather than a disease. A syndrome is a group of symptoms that collectively compose a condition or disease. The following characteristics are present in most women with PCOS:

• A genetic component. Many women with PCOS have female family members who exhibit symptoms and/or complications related to the disorder (e.g., irregular menstruation, excessive body hair growth, diabetes).
  
  
• Excess levels of insulin in the blood (hyperinsulinemia). Insulin is a hormone produced by the pancreas that allows the cells to absorb and use glucose for energy. When a person is insulin resistant, the cells throughout the body do not respond normally to insulin circulating in the blood. Insulin resistance causes hyperinsulinemia in women with PCOS. Hyperinsulinemia, in turn, may lead to glucose intolerance or type 2 diabetes.
  

  

• Excess levels of the luteinizing hormone (LH) secreted by the pituitary gland in the brain. Too much LH interferes with normal ovarian function. High levels of both LH and insulin stimulate the ovary to produce excessive male hormones (androgens). When the LH remains elevated and does not have a mid cycle surge or increase this also affects the release of the egg from the ovary.
  
  
• Abnormalities in the ovaries and adrenal glands, both of which are a significant factor in the syndrome.
  
  
• Abnormalities in the central nervous system. Cases of both hypothalamic and pituitary gland dysfunction have been reported.

The hormonal imbalance associated with PCOS brings about many signs and symptoms, including irregularities in the menstrual cycle (e.g., infrequent periods, amenorrhea), problems with the metabolic and cardiovascular systems and problems conceiving.

In addition, PCOS may result in the growth of many small cysts (fluid-filled sacs) in the ovaries that later become enlarged. Polycystic ovaries are enlarged ovaries that contain more than 12 follicular cysts, tiny follicles in the range of a quarter to half an inch (0.6 to 1.3 centimeters) in diameter. The hormonal changes may also result in the constant growth of the lining of the uterus (endometrium), which increases a woman’s risk of uterine cancer over time.

PCOS may be referred to as Stein Leventhal syndrome, named for the physicians who first encountered the disease. In 1935, Dr. Irving Stein and Dr. Michael Leventhal reported on a group of women with amenorrhea, infertility, hirsutism and enlarged polycystic ovaries. Though research into this condition has continued since that time, little is known about the nature and causes of PCOS.

Until very recently, the most widely accepted definition of PCOS was based upon diagnostic criteria recommended in 1990. The criteria classified it as a disorder characterized by chronic hyperandrogenism (high levels of testosterone and/or other androgens) and chronic anovulation (absence of ovulation) in the absence of other specific causes of these problems. But further research led to an international consensus in 2003 that expanded the diagnostic criteria to include women who exhibit any two of the following:

• Infrequent ovulation or anovulation
• Chronic hyperandrogenism
• Polycystic-appearing ovaries on ultrasound

If left untreated, the consequences of PCOS can put women at risk for:

• Heart disease
  
  
• High blood pressure (hypertension) and pregnancy-induced hypertension
  
  
• High cholesterol
  
  
• Type 2 diabetes and gestational diabetes
  
  
• Endometrial cancer (a type of uterine cancer)
  
  
• Infertility
  
  
• Obesity
  
  

• Sleep apnea (a condition in which a person’s breathing stops and restarts several times during sleep)

PCOS is one of the most common hormonal disorders among women of childbearing age, which is considered from the onset of puberty or menstruation until menopause. According to the American Society for Reproductive Medicine (ASRM), about 5 percent of women in the United States have PCOS.

PCOS should be considered a factor in young girls who exhibit hirsutism, menstrual irregularities and/or obesity. If PCOS is diagnosed and treated early, the risk of developing the more serious complications (e.g., type 2 diabetes, uterine cancer) in adulthood is greatly reduced.