The absence of menstruation means no menstrual flow. Absent menstruation may be primary (no menstruation before age 16) or secondary (menstruation begins at the appropriate age, but later stops for more than 3 cycles or 6 months).

Absent menstruation is called amenorrhea.

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.

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

Causes of primary amenorrhea:

• Delay may be normal if puberty characteristics, such as breat development, are present by age 13
• Birth defects of the female reproductive system
• Lack of an opening in the membrane at the entrance of the vagina (hymen)
• Problem with the hypothalamus gland

Factors that can disrupt normal menstruation include:

• Drastic weight reduction
• Eating disorders
• Stress

Causes of secondary amenorrhea:

• Pregnancy
• Stress and anxiety
• Drastic weight reduction
• Hormonal imbalance (such as with polycystic ovarian syndrome)
• Endocrine disorders such as thyroid disease or pituitary disease/tumor
• Other illness
• Excessive exercise
• Menopause (normal for women over age 45)
• Medications, including birth control pills and other contraceptives
• Uterine scarring, usually from procedures such as 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. However, keep in mind that the delay is only normal if the girl displays some signs of puberty, such as breast development
• Consult your obstetrician to determine if you may be pregnant.
• For a missed period caused by drastic weight loss or obesity, proper diet is recommended.
• For a missed period resulting from excessive exercise, cut back to a more conservative workout program.

• You have never had a menstrual period and you are age 16 or older
• You have previously menstruated but have missed 3 or more periods in a row

The first step is to rule out pregnancy. This is done with a urine or blood test.

Next, the doctor will perform a physical exam and ask questions about your medical history, which 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 hair growth in a male pattern?
  • Is there excessive anxiety?

Tests that may be performed include:

• Progestin withdrawal (take a hormonal medicine for 7 to 10 days to trigger bleeding)
• Prolactin level
• Serum hormone levels such as testosterone levels
• Thyroid function studies, includingTSH (thyroid stimulating hormone
• Pregnancy test (serum HCG)
• FSH (follicle stimulating hormone level)
• LH (luteinizing hormone level)
• Pelvic ultrasound
• CT scan of the head may be done if a pituitary tumor is suspected

Treatment depends on the cause of the amenorrhea. Your doctor may tell you to make lifestyle changes if the absent menstruation is due to weight changes, physical activity, or stress level. If you have polycystic ovarian syndrome or athletic amenorrhea, you may be given hormonal contraceptives to treat the problem.

If the absent menstruation is caused by another systemic disorder, normal menstrual function usually returns after the primary disorder is treated. For example, if the primary disorder is thyroid or pituitary disease, medicines will be prescribed.

Young women with primary amenorrhea that is caused by birth defects may require medicine, 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.