The absence of menstrual flow may be primary (menstruation fails to begin before age 16) or secondary (menstruation begins at the appropriate age, but later ceases for 6 or more months in the absence of normal causes such as pregnancy, lactation, or menopause).

Many perfectly normal females begin to menstruate later than most (the median age is 12.8).

Pregnancy is often the first thought when a period is missed, but there are many reasons for having a late period.

The incidence of primary amenorrhea in the United States is less than 1%. The incidence of secondary amenorrhea (due to some cause other than pregnancy) is about 4% in the general population.

Increased risk is associated with extreme and prolonged exercise (particularly without adequate conditioning), body fat content less than 15% to 17%, extreme obesity, and taking hormonal supplements.

Symptoms associated with amenorrhea depend on the cause and may include the following:

• Headache
• Galactorrhea (breasts produce milk in a woman who is not pregnant or breast-feeding an infant)
• Visual loss (in rare cases of pituitary tumor)
• Marked weight gain or weight loss
• Dry vagina
• Increased hair growth in a "male" pattern (hirsutism)
• Voice changes
• Breast size changes

PRIMARY AMENORRHEA

• Normal delay of onset (up to age 16)
• Lack of an opening in the membrane at the entrance of the vagina (hymen)
• Drastic weight reduction
• Congenital abnormalities of the genital system
• Chromosomal abnormalities
• Extreme obesity

SECONDARY AMENORRHEA

• Pregnancy
• Anxiety over pregnancy may cause a missed period, thereby increasing the anxiety even further
• Drastic weight reduction
• Vigorous athletics
• Obesity
• Emotional distress
• Menopause (normal for women over age 45)
• Endocrine disorders such as thyroid disease or pituitary disease/tumor
• Drugs such as busulfan, chlorambucil, cyclophosphamide, oral contraceptives, phenothiazines, and non-oral contraceptives (such as Norplant and Depo-Provera)
• Dilation and curettage (D and C)

Treatment depends on the cause:

• For amenorrhea caused by normal delay of menstruation onset, have patience until age 16.
• For a missed period that may be caused by pregnancy, consult your obstetrician to confirm pregnancy.
• For a missed period caused by drastic weight loss or obesity, proper diet is recommended.
• For a missed period resulting from excessive exercise, use moderation and cut back to a more conservative program.

• There is no satisfactory explanation for a missed period.

The medical history will be obtained and a physical examination performed.

A complete health history will be obtained, including a menstrual history. Questions may include the following:

• Menstrual history
  • Are you a woman presently in a menstruating age range (over 12 and under 55)?
  • Are you sexually active?
  • Do you use birth control? What type?
• Quality
  • Was the previous menstrual period a normal amount?
  • Are the menses absent or decreased?
  • Do you usually have regular periods?
• Time pattern
  • When was your last menstrual period?
  • At what age did you have your first menstrual period?
  • Have you ever had normal periods?
• Aggravating factors
  • What medications do you take?
  • How much do you exercise?
• Other symptoms
  • What other symptoms are also present?
  • Is there breast tenderness?
  • Is there morning nausea and vomiting?
  • Is there a headache?
  • Is there a nipple discharge (and not breast feeding)?
  • Is there vision loss or change in vision?
  • Is there an unintentional weight gain?
  • Is there an unintentional weight loss?
  • Is there vaginal dryness?
  • Is there hair growth in a male pattern?
  • Are there voice changes?
  • Are there changes in the breast size?
  • Is there excessive anxiety?

A physical examination, including a pelvic examination, will be performed. In patients with secondary amenorrhea, physical and pelvic examinations must rule out pregnancy before diagnostic testing begins. The patient may be encouraged to discuss her fears and, if indicated, may be referred for psychological counseling.

Diagnostic tests that may be performed include:

• Endometrial biopsy
• Progestin withdrawal
• Prolactin level
• Serum hormone levels such as testosterone levels
• Thyroid function studies
• Pregnancy test (serum HCG)
• FSH (follicle stimulating hormone level)
• LH (luteinizing hormone level)
• TSH (thyroid stimulating hormone; other thyroid function tests)
• Karyotype to rule out the presence of Y chromosome abnormality
• CT scan of the head may be done if a pituitary tumor is suspected

Treatment depends on the cause of the amenorrhea. If it is caused by another systemic disorder, normal menstrual function usually returns after the primary disorder is treated. For example, if the primary disorder is hypothyroidism, then amenorrhea will be cured when the thyroid disorder is treated with thyroid supplements.

Pituitary tumors are usually treated with bromocriptine, a drug that inhibits prolactin secretion. Surgery removal may also be suggested. Radiation therapy is usually reserved for situations where other medical or surgical treatment regimens are not successful.

A progestin challenge may be used to determine a course of treatment. In this test, daily estrogen supplements are given in conjunction with intermittent progestin for 10 to 14 days per month every 1 to 3 months. Hormonal supplements are commonly utilized for those women who do not bleed in response to the progestin challenge test.

Women who bleed in response to the progestin challenge test are anovulatory -- they do not menstruate because they do not ovulate. This common cause of amenorrhea is treated by inducing ovulation with medication such as clomiphene citrate (Clomid) -- but only if the patient desires pregnancy. In patients who have no immediate plan for pregnancy, on the other hand, oral contraceptive pills may be prescribed to induce cyclic menstruation to prevent uncontrolled growth of the endometrial lining.

Young women with primary amenorrhea, found to be caused by developmental abnormalities, may require hormonal supplementation, surgery, or both. In any case, psychosocial support and counseling for the patient and family is necessary to address specific concerns and provide guidance regarding anticipated sexual development.