Polycystic Ovary syndrome

Also known as: Stein-Leventhal syndrome


The ovaries are a pair of glands that make ova (eggs) and various hormones. Ovulation normally occurs once a month when a woman releases an egg. Before an ovum is released, it develops within a little swelling of the ovary called a follicle. Each month several follicles start to develop, but just one fully develops and goes on to ovulate. The ovaries make the two female sex hormones oestrogen and progesterone as well as a small amount of the male sex hormone testosterone.

Polycystic ovary syndrome (PCOS) is a condition where at least two of the following occur:

  • at least 12 follicles develop on the ovaries
  • the balance of hormones made in the ovaries is altered, which includes an increase in testosterone levels
  • although the ovaries usually have many follicles, they do not develop fully and so ovulation, and as a result menstrual bleeding, often does not occur.


Medical text written November 2011 by Professor Adam Balen, Professor of Reproductive Medicine and Surgery, Leeds Teaching Hospitals, Leeds, UK.

What are the symptoms?

Symptoms typically begin in the late teens or early twenties and can include:

  • irregular periods, light periods or no periods at all
  • infertility due to irregular or no ovulation
  • hirsutes (excess hair growth)
  • persistent acne
  • thinning of scalp hair
  • weight gain.

What are the causes?

There are a number of possible causes and there is no doubt that PCOS runs in families. Insulin is a hormone that controls blood sugar levels and it also acts on the ovaries causing them to produce testosterone. Some women with PCOS have insulin resistance, therefore, cells in the body are resistant to the effect of a normal level of insulin and so more insulin is produced to keep the blood sugar normal. Increased insulin causes the ovaries to make too much testosterone and combined the high level of insulin and testosterone prevents ovulation. An increased testosterone level in the blood causes excess hair growth on the body, thinning of the scalp hair and contributes to weight gain.

Luteinising hormone (LH) is made in the pituitary gland. It stimulates the ovaries to ovulate and works alongside insulin to promote testosterone production. A high level of LH is found in about 4 in 10 women with PCOS. Although PCOS is not strictly inherited from parent to child, it may run in some families.

How is it treated?

A cream called eflornithine may be prescribed to rub on areas of skin with excessive hair growth. It works by counteracting an enzyme involved in making hair. The contraceptive pill Dianette is commonly prescribed to regulate periods, to help reduce hair growth and to reduce acne in women with PCOS. The contraceptive pill Yasmin has been shown to help if Dianette is not suitable, although any combined contraceptive pill can be effective. Other antitestosterone drugs are sometimes advised by a specialist if the above treatments do not help.

It is important to ensure that menstruation occurs regularly to prevent abnormal thickening of the womb lining, this can also be achieved with the combined contraceptive pill or alternatively a hormone called progesterone. If fertility is desired then drugs may be required to help stimulate regular ovulation – this requires careful supervision by a specialist infertility clinic.

Losing weight can help to reduce insulin-resistance, thus reducing testosterone levels. In women who may be at risk of type II diabetes because of insulin resistance, metformin, an insulin sensitising drug may be prescribed.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
PCOS is known to run in families, however, the genetic factors responsible and inheritance pattern are yet to be determined.

Prenatal diagnosis

Is there support?


Email: office@verity-pcos.org.uk
Website: verity-pcos.org.uk

Verity is a Registered Charity in England and Wales No. 1097599. It provides information and support for women with Polycystic Ovary Syndrome. Verity offers a discussion board where women can give and receive peer support, and organises twice yearly conferences. 

Group details last updated September 2014.

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