Secondary amenorrhoea is commoner so it will be discussed first and in more detail.
There are two areas of the brain which influence the menstrual cycle – the hypothalamus and the pituitary. The hypothalamus produces gonadotrophin releasing hormone (GnRH) which stimulates the anterior pituitary to produce luteinising hormone (LH) and follicle stimulating hormone (FSH). The anterior pituitary hormones then affect the ovaries causing release of oestradiol, progesterone and inhibin. These hormones have a intricate link and the timings and amounts affect the menstrual cycle.
The diagram below illustrates the influence of the brain and ovaries on the production of hormones.
Again, the causes can be split into the various levels.
Commonly it can be constitutional, often following a family pattern, which is the commonest cause. However, it can also be due to the effect of other chronic illnesses such as diabetes.
Anorexia nervosa or excessive exercise can be a cause in teenagers. Problems with the development of the pituitary or tumours of the pituitary or hydrocephalus are much rarer causes.
Problems with the normal functioning of the ovaries or the absence of ovaries can also result in no menses. This can be due to abnormal development, premature ovarian failure, genetic problems, autoimmune disease, infections or following chemotherapy/ radiotherapy.
Genetic problems can be a rare cause of amenorrhoea e.g. Turner syndrome which is when the child only has one copy of the X chromosome.
Anatomical causes are more common in primary amenorrhoea:
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