WOMEN'S HEALTH Menstruation • Premenstrual syndrome (PMS) • Menorrhagia (heavy menstrual bleeding) • Menstrual cramps (dysmenorrhea) • Mittelschmerz • Amenorrhea

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Amenorrhea — the absence of menstruation — can happen during puberty or later in life. Primary amenorrhea describes a condition in which you haven't had any menstrual periods by age 16. Secondary amenorrhea occurs when you were previously menstruating but then stopped having periods. Pregnancy may be your first thought if you miss a period, but there are many reasons why you might not be menstruating regularly.

A symptom, not a disease, amenorrhea seldom results from a serious condition. However, not knowing why menstruation has stopped can be stressful, and waiting for it to recur may feel like a lifetime. But don't hit the panic button. With a little investigation into your medical history and an accurate description of what you're experiencing, you and your doctor can get to the root of the problem. Treating the underlying problem can resolve amenorrhea.

The main indication that you might have amenorrhea is that you don't have menstrual periods. Here's what to look for in primary and secondary amenorrhea:

• Primary amenorrhea. You have no menstrual period by age 16.
• Secondary amenorrhea. You have no periods for three to six months or longer.

Depending on the cause of amenorrhea, you might experience other signs or symptoms along with the absence of periods, such as milky nipple discharge, headache, vision changes, hair loss or excess facial hair.

Primary amenorrhea
Primary amenorrhea affects approximately 1 in 1,000 adolescent girls in the United States. The most common causes of primary amenorrhea include:

• Chromosomal abnormalities. Certain chromosomal abnormalities can cause a premature depletion of the eggs and follicles involved in ovulation and menstruation.
• Problems with the hypothalamus. Functional hypothalamic amenorrhea is a disorder of the hypothalamus — an area at the base of your brain that acts as a control center for your body and regulates your menstrual cycle. Excessive exercise, eating disorders such as anorexia, and physical or psychological stress can all contribute to a disruption in the normal function of the hypothalamus. Less commonly, a tumor may prevent your hypothalamus from functioning normally.
• Pituitary disease. The pituitary is another gland in the brain that's involved in regulating the menstrual cycle. A tumor or other invasive growth may disrupt the pituitary gland's ability to perform this function.
• Lack of reproductive organs. Sometimes problems arise during fetal development that lead to a baby girl being born without some major part of her reproductive system, such as her uterus, cervix or vagina. Because her reproductive system didn't develop normally, she won't have menstrual cycles.
• Structural abnormality of the vagina. An obstruction of the vagina may prevent menstrual periods from occurring. A membrane or wall may be present in the vagina that blocks the outflow of blood from the uterus and cervix.

Secondary amenorrhea
Secondary amenorrhea is much more common than primary amenorrhea. Many possible causes of secondary amenorrhea exist:

• Pregnancy. In women of reproductive age, pregnancy is the most common cause of amenorrhea. When a fertilized egg is implanted in the lining of your uterus, the lining remains to nourish the fetus and isn't shed by menstruation.
• Contraceptives. Some women who take birth control pills may not have periods. When oral contraceptives are stopped, it may take three to six months to resume regular ovulation and menstruation. Contraceptives that are injected or implanted, such as Depo-Provera, also may cause amenorrhea, as can progesterone-containing intrauterine devices, such as Mirena.
• Breast-feeding. Mothers who breast-feed often experience amenorrhea. Although ovulation may occur, menstruation may not. Pregnancy can result despite the lack of menstruation.
• Stress. Mental stress can temporarily alter the functioning of your hypothalamus — an area of your brain that controls the hormones that regulate your menstrual cycle. Ovulation and menstruation may stop as a result. Regular menstrual periods usually resume after your stress decreases.
• Medication. Certain medications can cause menstrual periods to stop. For example, antidepressants, antipsychotics, some chemotherapy drugs, and oral corticosteroids can cause amenorrhea.
• Illness. Chronic illness may postpone menstrual periods. As you recover, menstruation typically resumes.
• Hormonal imbalance. A common cause of amenorrhea or irregular periods is polycystic ovary syndrome (PCOS). This condition causes relatively high and sustained levels of estrogen and androgen, a male hormone, rather than the fluctuating condition seen in the normal menstrual cycle. This results in a decrease in the pituitary hormones that lead to ovulation and menstruation. PCOS is associated with obesity; amenorrhea or abnormal, often heavy uterine bleeding; acne and sometimes excess facial hair.
• Low body weight. Excessively low body weight interrupts many hormonal functions in your body, potentially halting ovulation. Women who have an eating disorder, such as anorexia or bulimia, often stop having periods because of these abnormal hormonal changes.
• Excessive exercise. Women who participate in sports that require rigorous training, such as ballet, long-distance running or gymnastics, may find their menstrual cycle interrupted. Several factors combine to contribute to the loss of periods in athletes, including low body fat, stress and high energy expenditure.
• Thyroid malfunction. An underactive thyroid gland (hypothyroidism) commonly causes menstrual irregularities, including amenorrhea. Thyroid disorders can also cause an increase or decrease in the production of prolactin — a reproductive hormone generated by your pituitary gland. An altered prolactin level can affect your hypothalamus and disrupt your menstrual cycle.
• Pituitary tumor. A noncancerous (benign) tumor in your pituitary gland (adenoma or prolactinoma) can cause an overproduction of prolactin. Excess prolactin can interfere with the regulation of menstruation. This type of tumor is treatable with medication, but it sometimes requires surgery.
• Uterine scarring. Asherman's syndrome, a condition in which scar tissue builds up in the lining of the uterus, can sometimes occur after uterine procedures, such as a dilation and curettage (D and C), Caesarean section or treatment for uterine fibroids. Uterine scarring prevents the normal buildup and shedding of the uterine lining, which can result in very light menstrual bleeding or no periods at all.
• Premature menopause. Menopause occurs at an average age of 51. If you experience menopause before age 40, it's considered premature. The lack of ovarian function associated with menopause decreases the amount of circulating estrogen in your body, which in turn thins your uterine lining (endometrium) and brings an end to your menstrual periods. Premature menopause may result from genetic factors or autoimmune disease, but often no cause can be found.

For primary or secondary amenorrhea, consult your doctor if:

• You've never had a menstrual period and you're age 16 or older
• You've previously menstruated but have missed two or more periods in a row

Although amenorrhea rarely results from a life-threatening condition, it can encompass a complex set of hormonal problems. Finding the underlying cause can take time and may require more than one kind of testing.

First, your doctor may have you take a pregnancy test. Your doctor may also perform a pelvic exam to check for pregnancy or any problems with your reproductive organs.

The next step may include blood tests to check your hormone levels, for instance a thyroid function test or evaluation of your prolactin level. A progestin challenge test — in which you take a hormonal medication (progestogen) for seven to 10 days to trigger bleeding — may be another kind of test your doctor administers. Results from this test can tell your doctor whether your periods have stopped due to a lack of estrogen.

Depending on your signs and symptoms — and the result of any blood tests you've had — further testing may be needed. Imaging tests, such as computerized tomography, magnetic resonance imaging or ultrasound, can reveal pituitary tumors or structural abnormalities in your reproductive organs. Finally, laparoscopy or hysteroscopy — minimally invasive surgical techniques to view your internal organs — may sometimes be recommended.

What type of treatment you need — if any — depends on what's causing the amenorrhea. Your doctor may suggest that you make changes to your lifestyle depending on your weight, physical activity or stress level. If you have PCOS or athletic amenorrhea, your doctor may prescribe oral contraceptives to treat the problem. Amenorrhea caused by thyroid or pituitary disorders may be treated with medications.

The best way to avoid an interruption in your menstrual cycle is to maintain a healthy lifestyle:

• Make changes in your diet and exercise activity to achieve a healthy weight.
• Strive for a healthy balance in work, recreation and rest.
• Assess areas of stress and conflict in your life. If you can't decrease stress on your own, ask for help from family, friends or your doctor.

Be aware of changes in your menstrual cycle and check with your doctor if you have concerns. Keep a record of when your periods occur. Note the date your period starts, how long it lasts and any troublesome symptoms you might experience.

Talk to your mother, sister or other close female relatives. Has anyone else in your family had a similar problem? Gathering this information can help your doctor determine what's causing your amenorrhea.

Amenorrhea may cause anxiety, but by working with your doctor, you can determine the cause and find ways to regulate your cycle.