Causes of Polycystic Ovary Syndrome
Although first described over 65 years ago, we still do not know the exact cause of PCOS. Theories regarding the mechanism(s) include the effects of abnormal pituitary hormone secretion, high levels of insulin, and abnormal production of male hormones by the ovary.
The pituitary gland secretes two hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In general, LH controls the production of female hormones (estrogen and progesterone) in the ovary and FSH controls the development and release of eggs in the ovary. LH and FSH are released in pulses from the pituitary gland in response to stimulation by gonadotropin releasing hormone (GnRH) from the brain. LH and FSH secretion normally varies throughout the menstrual cycle, and it appears that different patterns of GnRH pulses from the brain affect the different patterns of LH and FSH secretion. Specifically, fast GnRH pulses appear to favor LH secretion, and slow GnRH pulses favor FSH secretion. Estrogen and progesterone from the ovary regulate how frequently the brain secretes GnRH pulses, and also the amount of GnRH secreted per pulse.
A key point is that the pulses of GnRH are slowed by the elevated levels of estrogen and progesterone that normally occur after ovulation. Studies suggest that this slowing of GnRH allows for later FSH secretion (at the time of menstruation), which normally leads to egg development in the next cycle. These same studies would suggest that if GnRH pulses are not slowed down, subsequent FSH production is diminished. One can therefore see that this ability to slow GnRH pulses seems to be quite important for subsequent FSH secretion, and therefore subsequent development of an egg.
Studies have shown that GnRH secretion in patients with PCOS is relatively fast, and that it does not slow down very well in response to estrogen and progesterone. We believe that this helps to explain why PCOS patients frequently do not ovulate. Women with PCOS often have high levels of LH secretion. High levels of LH contribute to the high levels of androgens (male hormones such as testosterone), and this along with low levels of FSH contributes to poor egg development and an inability to ovulate. A lack of ovulation also leads to relative deficiencies of progesterone production by the ovary, which often leads to absence of menstrual periods.
Description of PCOS
Polycystic ovary syndrome (PCOS), originally described in 1935 by Stein and Leventhal, is an endocrine (hormonal) disorder characterized by anovulation (lack of ovulation), hirsutism, obesity, and the presence of multiple ovarian cysts. PCOS affects about 6% of women of childbearing age in the United States and is a leading cause of infertility.
Symptoms usually present themselves during adolescence but may also begin to appear in the early to mid 20s. While not every woman with PCOS will have the same presentation, some of the common physical symptoms of PCOS include the following:
- Irregular or absent menstrual periods
- Hirsutism (excessive hair growth on the face, chest, abdomen)
- Infertility or reduced fertility
- Multiple cysts in the ovaries (seen on ultrasound only)
- Insulin resistance
- Hair loss
How is PCOS diagnosed?
PCOS is most appropriately diagnosed by both blood tests and/or ultrasound. An ultrasound test can be used to assess whether polycystic ovaries are present. However, a diagnosis of PCOS should not be based on ultrasound alone because multiple cysts in the ovaries are not present in all women, and cysts can be present in normal ovaries.
Blood tests can provide a more definitive diagnosis of PCOS. Elevated levels of androgens, elevated fasting insulin and/or glucose levels, elevated levels of LH, and an elevation in the ratio of LH to FSH are all biochemical findings consistent with PCOS.
What are the treatments for PCOS?
Although there is no cure for PCOS, the symptoms are manageable by medications and changes in diet and exercise. Daily oral contraceptive pills and/or spironolactone are used to decrease excess facial and body hair. A healthy diet and regular exercise can control weight gain helping to lower insulin levels. Medications such as Clomid, metformin (Glucophage), or gonadotropins can be used to induce ovulation.