Polycystic ovary syndrome
What is it?
Polycystic ovary syndrome (PCOS) is the most common hormonal disorder among women of reproductive age. The name of the condition comes from the appearance of the ovaries in most, but not all, women with the disorder — enlarged and containing numerous small cysts located along the outer edge of each ovary (polycystic appearance).
Infrequent or prolonged menstrual periods, excess hair growth, acne and obesity can all occur in women with polycystic ovary syndrome. Menstrual abnormality may signal the condition in adolescence, or PCOS may become apparent later following weight gain or difficulty becoming pregnant.
The exact cause of polycystic ovary syndrome is unknown. Women with polycystic ovary syndrome may have trouble becoming pregnant due to infrequent or lack of ovulation. Early diagnosis and treatment of polycystic ovary syndrome can help reduce the risk of long-term complications, such as type 2 diabetes, heart disease and stroke.
Polycystic ovary syndrome signs and symptoms often begin soon after you first begin having periods (menarche). In some cases, PCOS develops later on during your reproductive years, for instance, in response to substantial weight gain.
Signs and symptoms vary from person to person, in both type and severity. To be diagnosed with the condition, your doctor looks for at least two of the following:
- Menstrual abnormality. This is the most common characteristic. Examples of menstrual abnormality include menstrual intervals longer than 35 days; fewer than eight menstrual cycles a year; failure to menstruate for four months or longer; and prolonged periods that may be scant or heavy.
- Excess androgen. Elevated levels of male hormones (androgens) may result in physical signs, such as excess facial and body hair (hirsutism); adult acne or severe adolescent acne; and male-pattern baldness (androgenic alopecia). However, the physical signs of androgen excess vary with ethnicity, so depending on your ethnic background you may or may not show signs of excess androgen. For instance, women of Northern European or Asian descent may not be affected.
- Polycystic ovaries. Enlarged ovaries containing numerous small cysts can be detected by ultrasound. Despite the condition's name, polycystic ovaries alone do not confirm the diagnosis. To be diagnosed with PCOS, you must also have abnormal menstrual cycles or signs of androgen excess. Some women with polycystic ovaries may not have PCOS, while a few women with the condition have ovaries that appear normal.
Other conditions associated with PCOS
- Infertility. Women with polycystic ovary syndrome may have trouble becoming pregnant because they experience infrequent ovulation or a lack of ovulation. PCOS is the most common cause of female infertility.
- Obesity. About half the women with polycystic ovary syndrome are obese. Compared with women of a similar age who don't have polycystic ovary syndrome, women with PCOS are more likely to be overweight or obese.
- Prediabetes or type 2 diabetes. Many women with polycystic ovary syndrome are insulin resistant, which impairs the body's ability to use insulin effectively to regulate blood sugar. This can result in high blood sugar and type 2 diabetes. Prediabetes is also called impaired glucose tolerance.
- Acanthosis nigricans. This is the medical term for darkened, velvety skin on the nape of your neck, armpits, inner thighs, vulva or under your breasts. This skin condition is a sign of insulin resistance.
Your normal reproductive cycle is regulated by changing levels of hormones produced by the pituitary gland in your brain and by your ovaries. The pituitary gland produces follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which control the growth and release of eggs (ovulation) in the ovaries. During a monthly cycle, ovulation occurs about two weeks before your period.
Your ovaries secrete the hormones estrogen and progesterone, which prepare the lining of the uterus to receive a fertilized egg. The ovaries also produce some male hormones (androgens), such as testosterone. If pregnancy doesn't occur, estrogen and progesterone secretion decline and the lining of the uterus is shed during menstruation.
In polycystic ovary syndrome, the pituitary gland may secrete high levels of LH and the ovaries may make excess androgens. This disrupts the normal menstrual cycle and may lead to infertility, excess body hair and acne.
Doctors don't know the cause of polycystic ovary syndrome, but these factors likely play a role:
- Excess insulin. Insulin is the hormone produced in the pancreas that allows cells to use sugar (glucose), your body's primary energy supply. If you have insulin resistance, your ability to use insulin effectively is impaired, and your pancreas has to secrete more insulin to make glucose available to cells. The excess insulin is thought to boost androgen production by your ovaries.
- Low-grade inflammation. Your body's white blood cells produce substances to fight infection in a process called inflammation. Eating certain foods can trigger an inflammatory response in some predisposed people. When this happens, white blood cells produce substances that can lead to insulin resistance and cholesterol accumulation in blood vessels (atherosclerosis). Atherosclerosis causes cardiovascular disease. Research has shown that women with PCOS have low-grade inflammation.
- Heredity. If your mother or sister has PCOS, you might have a greater chance of having it, too. Researchers also are looking into the possibility that mutated genes are linked to PCOS.
- Abnormal fetal development. New research shows that excessive exposure to male hormones (androgens) in fetal life may permanently prevent normal genes from working the way they're supposed to — a process known as gene expression. This may promote a male pattern of abdominal fat distribution, which increases the risk of insulin resistance and low-grade inflammation. Research continues to establish to what extent these factors might contribute to PCOS.
Researchers continue to explore possible causes of PCOS. Among topics of current research are whether low-grade inflammation and fetal exposure to excessive androgens might trigger the condition.
Having polycystic ovary syndrome makes the following conditions more likely, especially if obesity also is a factor:
- Type 2 diabetes
- High blood pressure
- Cholesterol abnormalities, such as high triglycerides or low high-density lipoprotein (HDL) cholesterol, the so-called "good" cholesterol
- Elevated levels of C-reactive protein, a cardiovascular disease marker
- Metabolic syndrome, a cluster of signs and symptoms that indicate a significantly increased risk of cardiovascular disease
- Nonalcoholic steatohepatitis, a severe liver inflammation caused by fat accumulation in the liver
- Sleep apnea
- Abnormal uterine bleeding
- Cancer of the uterine lining (endometrial cancer), caused by exposure to continuous high levels of estrogen
- Gestational diabetes or pregnancy-induced high blood pressure, if you do become pregnant
There's no specific test to definitively diagnose polycystic ovary syndrome. The diagnosis is one of exclusion, which means your doctor considers all of your signs and symptoms and then rules out other possible disorders.
During this process, your doctor takes many factors into account:
- Medical history. Your doctor may ask questions about your menstrual periods, weight changes and other symptoms.Physical examination. During your physical exam, your doctor will note several key pieces of information, including your height, weight and blood pressure.
- Pelvic examination. During a pelvic exam, your doctor visually and manually inspects your reproductive organs for signs of masses, growths or other abnormalities.
- Blood tests. Your blood may be drawn to measure the levels of several hormones to exclude possible causes of menstrual abnormalities or androgen excess that mimic PCOS. Additional blood testing may include fasting cholesterol and triglyceride levels and a glucose tolerance test, in which glucose levels are measured while fasting and after drinking a glucose-containing beverage.
- Pelvic ultrasound. A pelvic ultrasound can show the appearance of your ovaries and the thickness of the lining of your uterus. During the test, you lie on a bed or examining table while a wand-like device (transducer) is placed in your vagina (transvaginal ultrasound). The transducer emits inaudible sound waves that are translated into images on a computer screen.