Amenorrhoea is the absence of periods (menstruation),
which also means no eggs are produced (anovulation).
In many cases, as in girls before puberty,
or during pregnancy, breastfeeding or the
menopause, this is normal and is called physiological
amenorrhoea. An associated condition known
as Oligomenorrhoea refers to infrequent periods,
usually every three to six months which may
be irregular and long. Primary
amenorrhoea is the failure to establish
menstruation. It is regarded as abnormal
if a girl has not started sexual physical
development and menstruation by the age
of 14, or if a girl with normal sexual physical
characteristics has not started menstruation
by the age of 16. Primary amenorrhoea affects
only about 3 girls per 1000.
Secondary amenorrhoea
is defined as the absence of menstruation
for six consecutive months in a woman who
previously had regular periods. Secondary
amenorrhoea implies a gynaecological disorder
or a general cause or disease.
Secondary amenorrhoea
affects about 3% of girls. Up to 50% of
competitive long-distance runners (running
80 miles per week) and up to 44% of ballet
dancers have amenorrhoea.
Causes
There
are many possible causes. They include:
- Excessive exercise.
It is particularly common in athletes
involved in endurance events.
- Being severely
underweight, as a result of an eating
disorder or illness. Regular menstruation
is unlikely if the body mass index (weight
in Kg divided by the height in metres
squared) is less than 19 (the normal range
is 20 to 25).
- Severe stress or
emotional disturbance
- A disorder of the
ovary that prevents eggs from being produced
- Various medical
drugs
- A reaction to stopping
the contraceptive pill. About one woman
in 100 will have amenorrhoea for three
to six months after stopping use of the
pill. This is commonest in women who have
taken the pill continuously without a
regular pill-free interval.
- Polycystic ovary
syndrome: a condition associated with
multiple cysts in the ovaries, which features
menstrual disturbances or absence of menstruation,
sterility, obesity and a male distribution
of body hair from hormonal disturbances.
Severe long-term illness, or under- or
over-activity of the thyroid gland.
- Abnormal operation
of the hormones controlling ovulation
and menstruation produced by the hypothalamus
gland (which in turn controls the pituitary
gland).
Rare causes
of amenorrhoea include:
- Absence at birth
of the vagina, or womb, or both
- A hymen that completely
closes off the vagina
There are rare cases
where the true sex of a child is confused
because of poorly developed genital organs
at birth.
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Amenorrhoea
