Causes of Polycystic Ovarian Syndrome

The precise cause of PCOS isn’t known although it may, to some degree, be inherited. The complex balance between a number of hormones, the body’s natural chemical messengers, is a key factor. In women with PCOS, levels of luteinising hormone, produced by the pituitary gland, and testosterone, produced by the ovaries, are often higher than normal. Its these changes that lead to irregular periods, excess body hair and the other features of PCOS. The way the body responds to insulin, known as insulin resistance, is also a factor. Higher levels of insulin caused by insulin resistance can also increase testosterone levels and this promotes obesity.

Symptoms of Polycystic Ovarian Syndrome

Most women with PCOS start to notice problems in their late teens or twenties.  A range of symptoms is possible, but most women experience one or two of the following:

  • absent, infrequent or irregular periods
  • infertility - absent or irregular ovulation makes it impossible or difficult to conceive without treatment
  • enlarged ovaries - polycystic ovaries are usually 1.5 to 3 times larger than normal. This can sometimes cause abdominal pains
  • obesity or weight gain - commonly fat-distribution is around the abdomen, giving a typical apple- (rather than pear) shaped appearance
  • hirsutism (excess hair) - can develop on the face, chest, stomach, breasts, thumbs, or toes
  • alopecia (thinning hair) - a male-pattern baldness can develop, with thinning at the top of the head and the temples
  • acne - increased male hormones can lead to acne and dandruff


Increased blood levels of male hormones such as testosterone (known as (hyperandrogenism)

Diagnosis of Polycystic Ovarian Syndrome

An ultrasound scan can show that the ovaries are enlarged or polycystic, usually with 10 or more cysts, 6-8 mm in diameter, on the surface of the ovary. An affected ovary is around three times larger than usual. Sometimes only one ovary is affected. If obvious features such as acne and hirsutism are present, there may not be any need to do blood tests, but raised levels of a luteinising hormone and testosterone will confirm the diagnosis.

Women with PCOS can have a number of different hormone-related imbalances and in some countries, such as the US, it is hormone levels and symptoms, rather than the presence of cysts that are the key to confirming a diagnosis.

The problems caused by PCOS come on gradually. If there’s a sudden development of male features such as rapid body hair growth or enlargement of the clitoris, blood tests should be done to rule out conditions such as adrenal gland over activity or ovarian tumours. The doctor may refer women with suspected PCOS to a hospital specialist in endocrinology (medicine relating to the hormones) or, if applicable, a fertility specialist.

Treatment of Polycystic Ovarian Syndrome


Lifestyle changes may be beneficial and losing excess weight is particularly helpful. Increasing levels of physical activity (such as brisk walking for half an hour per day) and eating a balanced diet, low in fat, makes getting to and staying at a healthy weight easier. Stopping smoking is also beneficial.

Acne can be helped by peeling agents such as retinoin (Retin A), and antibiotic liquids or creams applied directly to the skin.

Hirsutism can be controlled with depilatory creams, bleaching, shaving, waxing and plucking. Laser treatment and electrolysis can give more lasting results but need to be performed by suitable qualified professionals. Laser treatment is more appropriate than electrolysis for larger areas.

Medical treatments

Several drugs are useful in dealing with individual symptoms.


Tablet forms of antibiotics and isotretinoin (Roaccutane,  a powerful drug that can only be prescribed by a specialist), can help to control acne.


Oral contraceptives (the pill) can reduce acne and hirsutism by damping down the production of testosterone. They also make periods more regular. A combination of the female hormone ethinyl oestradiol and the drug cyproterone acetate, which suppresses male hormone activity, is usually used. This is available on prescription under the brand name Diane-35.

Infertility is usually treated with the drug clomiphene, which stimulates egg production. Up to 60% of women fall pregnant after six cycles of treatment. Weight loss improves the chance of the treatment being successful. If clomiphene doesn’t work, injections of hormones such as human menopausal gonadotrophin or follicle-stimulating hormone can be tried. Using laser to drill hole in the ovaries in order to reduce hormone production has been attempted, but further studies are needed to see whether this is going to be an effective option.

Preliminary trials of Metformin, a drug used for the treatment of diabetes, suggest that it may reduce hirsutism and improve fertility.

Other drugs which might help PCOS patients by reducing male hormone activity are currently being studied.

Last Updated: Aug 2017
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