Amenorrhoea is the absence of menstrual periods in a woman during her reproductive years.
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 (lactation).
Amenorrhoea may be caused by many factors, including:
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.
Patients may have the following signs and symptoms of amenorrhoea, in addition to the absence of menstrual periods:
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 their reproductive potential. A number of treatments are available, including:
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 syndrome (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: Dec 2014