Amenorrhea
Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: Charles Davis, MD, PhD
What is amenorrhea?
Amenorrhea is the medical term for the absence of menstrual periods, either on a
permanent or temporary basis. Amenorrhea can be classified as primary or
secondary. In primary amenorrhea, menstrual periods have never begun (by age
16), whereas secondary amenorrhea is defined as the absence of menstrual periods
for three consecutive cycles or a time period of more than six months in a woman
who was previously menstruating.
The menstrual cycle can be influenced by many internal factors such as
transient changes in hormonal levels, stress, and illness, as well as external or
environmental factors. Missing one menstrual period is rarely a sign of a
serious problem or an underlying medical condition, but amenorrhea of longer
duration may signal the presence of a disease or chronic condition.
What causes amenorrhea?
The normal menstrual cycle occurs because of changing levels of hormones made
and secreted by the ovaries. The ovaries respond to hormonal signals from the pituitary gland located at the
base of the brain, which is, in turn, controlled by hormones produced in the hypothalamus of the brain.
Disorders that affect any component of this regulatory cycle can lead to
amenorrhea. However, a common cause of amenorrhea in young females sometimes
overlooked or misunderstood by the individual and others, is an undiagnosed pregnancy. Amenorrhea in
pregnancy is a normal physiological function. Occasionally, the same underlying
problem can cause or contribute to either primary or secondary amenorrhea. For
example, hypothalamic problems, anorexia or extreme exercise can
play a major role in causing amenorrhea depending on the age of the person and
if she has experienced menarche.
Primary amenorrhea
Primary amenorrhea is typically the result of a genetic or anatomic condition
in young females that never develop menstrual periods (by age 16) and is not
pregnant. Many genetic conditions that are characterized by amenorrhea are
conditions in which some or all of the normal internal female organs either fail
to form normally during fetal development or fail to function properly. Diseases
of the pituitary gland and hypothalamus (a region of the brain important for the
control of hormone production) can also cause primary amenorrhea since these
areas play a critical role in the regulation of ovarian hormones.
Gonadal dysgenesis is the name of a condition in which the ovaries are
prematurely depleted of follicles and oocytes (egg cells) leading to premature
failure of the ovaries. It is one of the most common cases of primary amenorrhea
in young women.
Another genetic cause is Turner syndrome, in which women are
lacking all or part of one of the two X chromosomes normally present in the
female. In Turner syndrome, the ovaries are replaced by scar tissue and estrogen production is minimal,
resulting in amenorrhea. Estrogen-induced maturation of the external female genitalia and
sex characteristics also fails to occur in Turner syndrome.
Other conditions that may be causes of primary amenorrhea include androgen
insensitivity (in which individuals have XY (male) chromosomes but do not
develop the external characteristics of males due to a lack of response to
testosterone and its effects),
congenital adrenal hyperplasia, and
polycystic ovary syndrome (PCOS).
Secondary amenorrhea
Pregnancy is an obvious cause of amenorrhea and is the most common reason for
secondary amenorrhea. Further causes are varied and may include conditions that
affect the ovaries, uterus, hypothalamus, or pituitary gland.
Hypothalamic amenorrhea is defined as amenorrhea that is due to a disruption
in the regulator hormones produced by the hypothalamus in the brain. These
hormones influence the pituitary gland, which in turn sends signals to the
ovaries to produce the characteristic cyclic hormones. A number of conditions
can affect the hypothalamus and lead to hypothalamic amenorrhea, such as:
- extreme weight loss,
- emotional or physical stress,
- rigorous exercise, and
- severe illness.
Other types of medical conditions can cause secondary amenorrhea:
- tumors or other diseases of the pituitary gland that lead to elevated
levels of the hormone
prolactin (which is involved in milk production) also cause amenorrhea due
to the elevated prolactin levels;
- hypothyroidism;
- elevated levels of androgens (male hormones), either from outside sources
or from disorders that cause the body to produce too high levels of male
hormones;
- ovarian failure (premature ovarian failure or early
menopause);
- polycystic ovary syndrome; and
- Asherman's syndrome is an example of uterine disease that causes
amenorrhea. It results from scarring of the
uterine lining following
instrumentation (such as dilation and curettage) of the
uterine cavity to manage postpartum bleeding or infection.
Post-pill amenorrhea
Women who have stopped taking oral contraceptive pills should
experience the return of menstruation within three months after discontinuing
pill use. Previously, it was believed that birth control pills increased a
woman's risk of amenorrhea following use of the pill, but this has been proven
not to be the case. Women who do not resume menstruation after three months have
passed since oral contraceptive pills were stopped should be evaluated for
causes of secondary amenorrhea.
Next: What are the symptoms of amenorrhea? »
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