Polycystic Ovarian Syndrome (PCOS)

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What is Polycystic Ovarian Syndrome?

Polycystic ovarian syndrome (PCOS), also known as Stein-Leventhal syndrome, is a common condition characterised by menstrual irregularities and symptoms or laboratory evidence of hyperandrogenism (excess levels of androgen). In many women with PCOS, polycystic ovaries will be detected on ultrasound.

PCOS was first described in 1935 as a collection of commonly occurring signs and symptoms. Since then, the criteria for diagnosing PCOS have changed several times. Most recently, the Rotterdam Consensus Conference agreed that PCOS may be diagnosed where any two of the following conditions are present:

Menstrual dysfunction: infrequent menstrual periods where no egg is released;
Clinical or laboratory evidence of hyperandrogenism (e.g. increased body hair, acne, high levels of testosterone on testing);
Polycystic ovaries on ultrasound.

Other characteristic features of PCOS include infertility, obesity and insulin resistance. PCOS is associated with an increased risk of developing endometrial or ovarian cancer, diabetes, high blood pressure, and cardiovascular disease. PCOS is a condition that can occur at any age, and is found in childhood, during puberty, in adolescence, adulthood and in the elderly.

Who gets Polycystic Ovarian Syndrome?

Polycystic ovarian syndrome is believed to be one of the most common hormonal abnormalities found in women. Depending on the criteria used to define the syndrome, PCOS may affect between 5 and 10% of women of reproductive age.

The presence of polycystic ovaries alone is not enough to achieve a diagnosis of PCOS. This is because multiple ovarian cysts are detected in as many as 20-25% of normal women on ultrasound examination.

Predisposing Factors

The cause of PCOS is poorly understood. A genetic (inherited) link is likely, but has not yet been identified.

One key factor in the development of PCOS is thought to be insulin resistance. The cells of the body become resistant to insulin, failing to respond normally. The body compensates for this by increasing insulin production, leading to hyperinsulinaemia (excess insulin in the blood). This in turn is thought to lead to the other problems of PCOS: excess androgen production, and abnormal production of the sex hormones responsible for regulating the menstrual cycle.

Progression

PCOS is a condition that can occur at any time during a woman's life. Depending on when the condition occurs, it can have varying effects. If PCOS occurs in an unborn baby, it can cause a small baby syndrome. If PCOS develops around puberty, it can cause problems with the start of a girl's period. PCOS during adolescence and adulthood will cause reduced periods, excess sex hormone levels, polycystic ovaries and, in 50%, obesity. In ageing individuals, the features of PCOS are diabetes, high blood pressure and abnormal blood lipid (cholesterol) levels; the combination of these findings is called the metabolic syndrome.

Period Problems:

These problems usually occur around puberty. There can be a delay in the onset of the first period (menarche), or normal menarche followed by a period of irregular bleeding and weight gain. Some women experience excessive menstrual bleeding (menorrhagia). Weight loss has been shown to be effective in allowing a return to normal cycles.

Excessive sex hormone levels:

This is seen in the following symptoms:

Hirsutism: excess thick pigmented body hair following a male distribution (e.g. on the upper lips, chin, around the nipples and on the abdomen).
Acne
Male-pattern balding

It is thought that approximately 50% of women with PCOS have elevated androgen levels. However, this figure depends on the androgen in question and the method of measurement.

Infertility:

Women with PCOS have irregular menstrual cycles. They also may not release an egg (ovulate) with each menstrual cycle. Combined, these factors can lead to a woman with PCOS having difficulty falling pregnant.

Obesity and insulin resistance:

Approximately 50% of women with PCOS suffer from obesity. Obesity can also be a cause of insulin resistance, but in women with PCOS the insulin resistance is not directly due to obesity.

Type 2 diabetes mellitus:

Women with PCOS have an increased risk of developing type 2 diabetes mellitus. This risk is particularly high in women who have a first degree relative with diabetes. There is a genetic link between PCOS and diabetes.

Other possible clinical manifestations of PCOS: