Absent and Infrequent Periods: What is oligomenorrhoea?

The commonest cause of secondary amenorrhoea resulting from pituitary problems is hyperprolactinaemia (elevated prolactin levels - normal range up to 500IU/l)). Prolactin is the hormone that promotes milk production (lactation) following childbirth. Hyperprolactinaemia is the state of higher than normal blood levels of this hormone. The main causes of hyperprolactinaemia are:-

stress (including seeing the doctor or having a blood test).

breast examination can cause prolactin levels to rise.

polycystic ovary syndrome (Q7. 2).

hypothyroidism (under active thyroid gland) can be associated with sustained moderate elevation of prolactin (>700IU/l).

some medicines, including antidepressants, cimetidene and methyldopa, may cause prolactin levels to rise.

a tumour of the pituitary gland (prolactinoma) suggesting the need for radiological examination of this area. Tiny pituitary tumours (microadenomas) tend to be associated with moderate elevation of prolactin. Larger tumours (larger than 1cm - macroadenomas) may be associated with prolactin levels greater than 5000 IU/l. At one time plain x-ray images were obtained but more modern sophisticated techniques (computerised tomography [CT]) or magnetic resonance imaging [MRI] are usually employed these days (Q4.10). Galactorrhoea (inappropriate milk production) occurs in about a third of women with hyperprolactinaemia, although there is no correlation between prolactin levels and the amount of milk produced.

diseases of the chest can be associated with hyperprolactinaemia on rare occasions.

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