Amenorrhea is the absence of menstruation in females. This condition typically excludes any absent menstruation (periods) for normal female function, such as before puberty, during pregnancy and/or breastfeeding or after menopause.

The abnormal absence of menstruation may be due to any number of changes in the organs, glands and hormones involved in the menstrual cycle. Possible medical causes of amenorrhea may include ovarian failure, problems in the central nervous system or the pituitary gland, hormonal imbalances, poor nutrition, stress or illness.

Amenorrhea may sometimes be accompanied by other symptoms, which may indicate that an underlying condition is present. For instance, when accompanied by acne, excessive hair growth (hirsutism) and rapid weight gain, amenorrhea may be caused by a hormonal imbalance associated with polycystic ovarian syndrome (PCOS). When accompanied by extreme weight loss, hair loss and other signs of malnutrition, it may indicate an eating disorder, such as anorexia nervosa.

Once it is determined that amenorrhea is not due to pregnancy, lactation or menopause, treatment will be determined based on the underlying condition. Treatments include diet and nutrition modifications, stress reduction techniques, birth control pills or hormone replacement therapy and, in rare cases, surgery.

Unless caused by a medical condition, menstrual irregularities such as amenorrhea may be prevented by maintaining a healthy lifestyle that includes a balanced diet and moderate exercise with plenty of rest. In addition, women should see their gynecologist (GYN) once a year for regular check-ups and report any irregularities or changes in their menstrual cycle to their physician.

Amenorrhea is the medical term to describe the absence of menstruation in women of a childbearing age (from the onset of puberty to menopause). It generally excludes any absent menstruation caused by normal body functions, such as occurs during pregnancy, breastfeeding and the period prior to menopause (perimenopause).

Amenorrhea is classified into two categories:

• Primary amenorrhea. When a girl has not had her first menstrual period (menarche) by age 16. It is also referred to as “delayed menarche.”
  
  
• Secondary amenorrhea. When a woman who has previously menstruated fails to menstruate for at least three months.

These terms are used only to describe the timing of amenorrhea and do not indicate cause.

Regular menstrual cycle begins when the brain's hypothalamus and pituitary gland release certain messenger hormones, such as gonadotropin (called GnRH for gonadotropin-releasing hormone), follicle stimulating (FSH) and luteinizing (LH) hormones. In response, the ovaries secrete estrogen and progesterone at different times to regulate the menstrual cycle.

Estrogen stimulates and promotes the growth of the endometrium. Progesterone, which forms after ovulation and is secreted from tissue known as the corpus luteum, transforms the rapidly growing endometrium into secretory endometrium. This will serve as the precursor for the future development of the placenta if pregnancy does occur. If pregnancy does not occur, this secretory endometrium breaks down and sheds during the ensuing menstrual period.

Amenorrhea can occur if problems occur with GnRH, the element that controls the hormones responsible for ovulation and the menstrual cycle (e.g., FSH, LH). A number of factors can cause the hypothalamus to decrease or stop releasing GnRH. This can result in inadequate production of estrogen or in progesterone and failure of ovulation.

An overproduction of male hormones (androgens) can also lead to amenorrhea. Too many androgens (as opposed to the normal balance between androgen and estrogen levels) results in a decrease in the pituitary hormones that lead to ovulation and menstruation.

In addition, the functions of the thyroid gland can affect a woman’s reproductive system, particularly if the thyroid is overactive or underactive. Thyroid disorders can affect the hypothalamus and disrupt the menstrual cycle causing a woman to have absent periods. Plus, thyroid disorders can have an effect on the production of the hormone prolactin, which can also result in a cessation in menstrual periods. 

In other cases, the hypothalamus, pituitary and ovaries all may be functioning normally, yet amenorrhea may occur as a result of adhesions or scars in the endometrial cavity. These scars prevent the normal buildup and shedding of the uterine lining, which can result in very light or absent menstruation.

Structural disorders can also play a role in amenorrhea. Chromosomal abnormalities may arise during fetal development that lead a female infant to be born without a major part of her reproductive system, such as the uterus, cervix or vagina. Or, a membrane or wall present in the vagina may block the outflow of blood from the uterus and cervix. In these cases, women will undergo puberty but will not experience menstruation.

Regular menstrual cycles are a sign of good health. They mean that a woman’s reproductive system is working properly. Women who miss their periods (unrelated to pregnancy) may want to talk with a physician to make sure they do not have an underlying condition.

In addition, women who get fewer than six or eight periods a year (oligomenorrhea) may also want to consult with a physician. Oligomenorrhea may be common for girls in early puberty, but after this period it may indicate a hormonal imbalance such as polycystic ovarian syndrome.

Amenorrhea and oligomenorrhea have been associated with long-term health consequences. For instance, the loss of menstrual regularity has been associated with increased risk of uterine cancer (because the lining of the uterus is not shed monthly), reduced bone density and increased fracture rates, as well as future fertility concerns.

Amenorrhea may be accompanied by various other symptoms depending on its underlying cause. Accompanying symptoms may help physicians to diagnose conditions causing the absence of menstruation. Related symptoms may include:

• Extreme loss of weight due to an eating disorder (e.g., anorexia nervosa, bulimia) or serious illness (e.g., cancer)
  
  
• Acne, excess body hair (hirsutism) or excessive weight gain, among other symptoms associated with polycystic ovarian syndrome (PCOS)
  
  
• Secretions of the breast not related to pregnancy or nursing (galactorrhea) due to high levels of the hormone prolactin in the blood (hyperprolactinemia)
  
  
• Arthritis, loss of sexual desire and shortness of breath (dyspnea) caused by excessive amounts of iron in the body resulting from hemochromatosis
  
  
• Underactive thyroid gland (hypothyroidism)
  
  
• Low blood pressure, lack of breast milk production and loss of pubic hair caused by a rare condition involving the pituitary gland can occur in women after severe blood loss during childbirth (Sheehan syndrome)
  
  
• Weight gain around the midsection and upper back, exaggerated facial roundness, high blood pressure and muscle weakness occurring when the body produces and/or is exposed to high levels of the hormone cortisol for a prolonged period of time (Cushing syndrome)

The term amenorrhea is most often used by physicians to describe the absence of menstruation. The absence of menstruation is most often caused by normal body functions such as:

• Pregnancy. This is the most common cause of amenorrhea in women of reproductive age. When a woman’s egg is implanted in the lining of the uterus, the lining remains to nourish the fetus and is not shed by menstruation.
  
  
• Breastfeeding. Women who lactate often experience amenorrhea for up to six months.
  
  
• During perimenopause and/or after menopause. Some women may experience early menopause (before age 40). The lack of normal ovulatory function associated with menopause – defined as the cessation of menses for 12 months which then becomes permanent – decreases the amount of estrogen in a woman’s body, which results in menstruation stopping. Some women may experience irregular periods before complete amenorrhea.

Some women who take birth control pills may not have periods when they first begin taking the medication. It can take up to three months before a cycle becomes evident. With some low-dose birth control pills, women may experience a day or two of light spotting instead of a regular period. This is normal because the low dose of hormone in the pill results in the development of only a very small amount of lining in the uterus. Menstruation usually resumes after about three months. Also, when oral contraceptives are stopped, it may take up to six months for a regular menstrual cycle to occur. Contraceptives administered by injections, patches or those that are implanted may also cause the temporary cessation of menstrual periods.

In addition, progesterone-containing intrauterine devices (IUDs) may cause amenorrhea in some women. However, women who experience prolonged amenorrhea while on birth control should contact their physician to rule out pregnancy. Other causes of amenorrhea that are not associated with normal gynecological function include the following:

• Excessive exercise. Women who regularly participate in sports that require rigorous training (e.g., ballet, gymnastics) may fail to menstruate. Other factors combined with the excessive physical activity may also contribute to the loss of periods in athletes, including low body fat, stress and high-energy expenditure. Excessive exercise requires vigorous training several hours per day and when this is combined with inadequate intake of calories, vitamins and minerals, amenorrhea may result.
  
  
• Low body weight or obesity. Excessively low or high body weight interferes with many of the body’s hormonal functions and may interrupt ovulation. For example, malnourished women or those with eating disorders (e.g., anorexia nervosa, bulimia) or excessive body fat (obesity) often stop having periods due to abnormal hormonal changes.
  
  
• Stress. Mental stress can temporarily disrupt the functioning of the hypothalamus gland, which may result in the cessation of ovulation and menstruation. However, regular menstrual periods usually resume after a reduction of stress.
  
  
• Polycystic ovarian syndrome (PCOS). Altered hormone levels, such as occurs when PCOS is present, may interfere or prevent ovulation, resulting in amenorrhea. With PCOS, women may have high levels of male hormones (androgens) present that interfere with ovulation and the menstrual cycle. Women with PCOS may menstruate infrequently (oligomenorrhea) or not at all.
  
  
• Chronic illness. Diseases that affect the immune system such as diabetes, HIV or cancer may interfere with a woman’s menstrual cycle. Epilepsy (a chronic disorder of brain function that causes seizures) may also result in amenorrhea.
  
  
• Medications. Some medications may cause a woman’s menstrual period to cease. For example, antidepressants, antipsychotics, some chemotherapy drugs and oral corticosteroids can cause amenorrhea.
  
  
• Cigarette, drug and/or alcohol abuse. The constant use of recreational drugs, such as cocaine or marijuana, has central effects that may disrupt a woman’s menstrual cycle. These drugs may result in low follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels and slowed GnRH release which interferes with ovulation. Excessive cigarette smoking (due to its anti-estrogenic effects) has also been associated with lack of menstruation. In addition, malnutrition and cirrhosis (a potentially life-threatening condition that affects liver function) associated with alcoholism may cause loss of menstrual regularity. 
  
  
• Turner syndrome (TS). A rare chromosomal abnormality that affects females and causes a premature depletion of the eggs and follicles involved in ovulation and menstruation. Women with TS do not have proper ovarian development and may experience delayed menarche or no menarche at all.
  
  
• Lack of reproductive organs. In some cases, problems arise during fetal development which may lead a female infant to be born without some vital part of her reproductive system, such as the uterus, cervix or vagina. In such cases, women with reproductive systems that did not develop normally will not have menstrual cycles.
  
  
• Structural abnormalities of the vagina. Sometimes there may be irregularities in the structure of a woman’s vagina that are present at birth but may go unnoticed until puberty. For example, a membrane or wall that blocks the outflow of blood from the uterus or cervix may be present.
  
  
• Tumors in the hypothalamus or pituitary gland may also interfere with secretion of hormones and result in amenorrhea.
  
  
• Thyroid disorders. An underactive thyroid gland (hypothyroidism) or an overactive one (hyperthyroidism) commonly causes menstrual irregularities, such as amenorrhea. In addition, thyroid disorders may cause an increase or decrease in the production of the hormone prolactin, which can affect the hypothalamus and disrupt a woman’s menstrual cycle.
  
  
• Asherman syndrome. The buildup of scar tissue in the lining of the uterus, which can sometimes occur after certain uterine procedures, such as dilation and curettage (D&C), Caesarean section (C-section) or treatment for uterine fibroids, may prevent the normal buildup and shedding of the lining of the uterus. This condition can result in very light or absent periods.

It is important to note that several hormonal disorders that result in the inability to regularly shed the endometrial lining of the uterus could put a woman at risk for developing uterine cancer. In addition, if left untreated for over 12 months it may also cause loss of bone density which can lead to osteoporosis.

The first step in determining the cause of amenorrhea is usually to rule out pregnancy and to check for any problems with a woman’s reproductive organs. This usually involves a pregnancy test along with a pelvic examination typically conducted by an obstetrician-gynecologist (ObGyn).

If pregnancy is ruled out, a physician will collect a thorough medical history, including a menstrual history, and ask questions about accompanying symptoms. Blood tests and/or urine tests may be performed to determine if hormone levels may be interfering with menstruation.

Depending on the signs and symptoms accompanying amenorrhea, further tests may be needed. For example, imaging tests such as an ultrasound can reveal tumors or structural abnormalities in a woman’s reproductive organs, as well as measure and monitor the endometrial lining. In addition, minimally invasive procedures, such as a laparoscopy or hysteroscopy, may sometimes be performed for a more thorough examination of the reproductive structures.

The treatment of amenorrhea depends on its cause. Treatments may include:

• Lifestyle changes. Changes to diet, exercise and stress management may help resolve some causes of amenorrhea or may be an integral part of the overall treatment plan.
  
  
• Medications. These include drugs primarily used to correct hormone disorders. For example, estrogen, progesterone or other hormone replacement therapy may be administered to restore a woman’s menstrual periods. Sometimes birth control pills are prescribed to help with irregular or absent periods.
  
  
• Surgery. Various procedures may be used to remove tumors or cysts in the ovaries, uterus or pituitary gland that is causing the lack of menstruation. Most tumors or cysts are noncancerous, but if cancer is present radiation therapy and/or chemotherapy may be necessary.

Most cases of amenorrhea are caused by a treatable medical condition, and once treated, a woman usually resumes menstruation.

A healthy lifestyle includes a balanced diet and regular exercise and is the best way to prevent irregularities in the menstrual cycle. This may be done by:

• Making appropriate changes in diet and exercise activity to achieve a healthy weight. Women may wish to consult a registered dietician for assistance with dietary changes.
  
  
• Avoiding excessive alcohol consumption and cigarette smoking.
  
  
• Striving for a healthy balance in work, recreation and rest.
  
  
• Assessing areas of stress or conflict in life. If necessary, contacting a psychologist or psychiatrist for help with dealing with stress.
  
  
• Receiving regular gynecological examinations according to a physician's recommended schedule.

A woman should keep track of changes in her menstrual cycle and check with her physician if she has any concerns. Keeping a record when periods occur and how long they last in addition to the accompanying symptoms is a good way to monitor gynecological health.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients or parents may wish to ask their doctor the following questions regarding amenorrhea:

1. What constitutes a normal menstrual cycle?
   
   
2. How many menstrual cycles do I have to miss before amenorrhea is diagnosed?
   
   
3. What tests will be done to diagnose this condition?
   
   
4. Do I have any structural problems that may be causing my amenorrhea?
   
   
5. Are there any lifestyle factors that may be contributing to my condition?
   
   
6. What are my treatment options?
   
   
7. What are the risks and benefits of these treatments?
   
   
8. Once I begin treatment, when will my periods become regular?
   
   
9. Will I always be at risk for amenorrhea?
   
   
10. How can I prevent future problems with menstruation?
    
    
11. What other conditions might I develop from amenorrhea?
    
    
12. How will this condition affect my fertility?
    
    
13. How will I know if I have reached menopause?
    
    
14. Will my daughters likely experience the same problems?