Absence of MENSTRUATION at the time of life at which it should normally occur. If menstruation has never occurred, the amenorrhoea is termed primary; secondary amenorrhoea is defined as menstruation ceasing after a normal cycle has been experienced for a number of years.

A few patients with primary amenorrhoea have an abnormality of their CHROMOSOMES or malformation of the genital tract such as absence of the UTERUS (see TURNER'S SYNDROME). A gynaecological examination will on rare occasions disclose an IMPERFORATE HYMEN in a young girl, who may also complain of regular cycles of pain like period pains.

There are many causes of secondary amenorrhoea and management requires identification of the primary cause. The commonest cause is pregnancy. Disorders of the HYPOTHALAMUS and related psychological factors such as anorexia nervosa (see EATING DISORDERS) also cause amenorrhoea, as can poor nutrition generally. It is common in ballet dancers and athletes who exercise a great deal and can be triggered by serious illnesses such as tuberculosis or malaria. Excess secretion of PROLACTIN, either due to a micro-adenoma (see ADENOMA) of the PITUITARY GLAND or to various prescription drugs, may produce amenorrhoea, and sometimes GALACTORRHOEA as well. Malfunction of other parts of the pituitary gland will cause failure to produce GONADOTROPHINS, thus causing ovarian failure with consequent amenorrhea. In CUSHING'S SYNDROME, amenorrhoea is caused by excessive production of cortisol. Similarly, androgen-production abnormalities are found in the common POLYCYSTIC OVARY SYNDROME. These conditions also have abnormalities of the insulin/glucose control mechanisms. Taking the contraceptive pill is not now considered to provoke secondary amenorrhoea but OBESITY and HYPOTHYROIDISM are potential causes.

When the cause is weight loss, restoring body weight may restore menstruation. Otherwise, measuring gonadotrophic hormone levels will help show whether amenorrhoea is due to primary ovarian failure or secondary to pituitary disease. Women with raised concentrations of serum gonadotrophic hormones have primary ovarian failure. When amenorrhoea is due to limited pituitary failure, treatment with CLOMIPHENE may be recommended.