Amenorrhoea is the absence of menstrual periods in a woman during her reproductive years (after the age of puberty but before the typical age of the menopause).
Amenorrhoea is classified as either ‘primary’ (menstrual periods not having started by age 16 years) or ‘secondary’, which is the absence of menstrual periods in a woman who has previously been menstruating for six months or more.
It is important to remember that amenorrhoea is normal before puberty, during pregnancy and after the menopause. Women may also experience amenorrhoea while breastfeeding (referred to as lactational ammenorrhoea).
Amenorrhoea may be caused by many factors, including:
• defects in one or more areas of the reproductive system, such as the hypothalamus and pituitary gland (parts of the brain regulating reproduction), ovaries, uterus or vagina
• a side-effect from treatment for cancer
• a symptom of endometrial cancer.
One of the most common types of amenorrhoea is ‘functional hypothalamic amenorrhoea’. This is where the onset of amenorrhoea can be linked to factors such as recent stress, change in weight, excessive dieting or exercise, or illness.
In addition to the absence of menstrual periods, patients may have the following signs and symptoms of amenorrhoea:
• headaches, visual disturbance or tiredness caused by diseases affecting the pituitary gland
• spontaneous flow of milk from the breasts caused by excessive levels of a hormone called prolactin. This is called galactorrhoea
• acne and/or excess body hair growing in male-pattern distribution caused by polycystic ovary syndrome
• symptoms of premature menopause (premature ovarian failure) such as hot flushes, vaginal dryness, poor sleep or reduced libido
• short stature and lack of secondary sexual characteristics (e.g. breast development) if premature ovarian failure is caused by the genetic condition Turner syndrome.
The frequency of primary amenorrhoea in the population is about 0.5–1.2%. The frequency of secondary amenorrhoea is approximately 5%.
The vast majority of causes of amenorrhoea are not inherited. Rarely, in patients with primary amenorrhoea, abnormalities in hypothalamic hormone production or defects in ovarian function may have been inherited. It is possible that family genetic history may play a role in some causes of secondary amenorrhoea.
The diagnosis of amenorrhoea is made from a history of lack of menstrual cycles. A pregnancy test must always be carried out to rule out pregnancy as the cause of amenorrhoea. Once this has been completed, initial blood tests include measurement of hormones involved in regulation of reproduction such as follicle stimulating hormone, prolactin, thyroid function tests and androgen levels.
In women who have never had menstrual periods, an ultrasound scan will be done to look at the uterus and the anatomy of the vagina.
All of these tests can be carried out as an outpatient.
Treatment of amenorrhoea depends on the underlying cause. Women are counselled regarding the cause and management of amenorrhoea, and any impact on their ability to conceive a child. A number of treatments are available, including:
• women who are very underweight through not eating enough or exercising too much often do not have periods; this may be resolved by putting on weight and/or exercising less
• surgery and/or medication may be required for pituitary conditions. Women with tumours producing excess prolactin are usually treated with a class of drugs called ‘dopamine agonists’, which reduce prolactin levels
• hormone replacement therapy (oestrogen plus progesterone in those with an undamaged uterus)
• prescribing the missing hypothalamic or pituitary hormones that regulate reproduction for women who want to become pregnant
• surgery may be required in patients with uterine or vaginal abnormalities dating from birth.
There are a number of side-effects to these treatments. For detailed information on these, please see the articles on prolactinoma (a type of pituitary tumour), premature ovarian failure (early menopause), polycystic ovary syndrome (caused by an imbalance of oestrogen and testosterone), congenital adrenal hyperplasia (an inherited condition characterised by low cortisol levels), hypothyroidism (an underactive thyroid gland) and thyrotoxicosis (an excess of thyroid hormones).
Any long-term implications of amenorrhoea often depend on the underlying cause of the condition.
Women with amenorrhoea are at risk of developing thin bones (osteoporosis) and fractures and should, therefore, have regular monitoring of bone density. They should also be counselled regarding the potential of conception and childbirth.
Last reviewed: May 2021