Hyperprolactinaemia

Question 1

what is the normal physiology of prolactin?

Answer 1

• prolactin is secreted by lactotroph cells in the anterior pituitary gland
• prolactin secretion is regulated by the hypothalamus, and this is predominantly under inhibitory control by hypothalamic dopamine
• conversely, thyrotropin-releasing hormone (TRH), serotonin and oestrogens can act to stimulate prolactin release
• the primary function of prolactin is to stimulate breast tissue proliferation during pregnancy and breast milk production post-partum
• prolactin also inhibits luteinising hormone (LH) and follicle-stimulating hormone (FSH) secretion

Question 2

what are the causes of hyperprolactinaemia?

Answer 2

• physiological (e.g. stress, sexual intercourse, pregnancy, lactation, exercise)
• drug-related (e.g. antipsychotic, antidepressant, antiemetic)
• pathological (e.g. prolactinoma, compression of the pituitary stalk by meningioma, craniopharyngioma, or growth hormone-secreting pituitary adenoma)
• CKD
• hepatic cirrhosis
• polycystic ovarian disease
• hypothyroidism
• sarcoidosis

Question 3

what is a prolactinoma?

Answer 3

• a tumour originating from the lactotroph cells of the anterior pituitary gland
• can be microprolactinomas (<10mm size) or macroprolactinomas (>10mm size)

Question 4

what are the symptoms of hyperprolactinaemia?

Answer 4

• due to the direct effects of raised prolactin: amenorrhoea, oligomenorrhoea, infertility, galactorrhoea, reduced libido, erectile dysfunction in men
• due to tumour (usually macroprolactinomas): headache, visual disturbances +/- other pituitary deficiencies or excess (e.g. growth hormone co-secretion)

Question 5

what are the signs on examination of hyperprolactinaemia?

Answer 5

• visual field defect (e.g. bilateral temporal hemianopia (due to a pituitary adenoma compressing the optic chiasm))
• cranial nerve palsy
• gynaecomastia
• galactorrhoea
• concomitant dysfunction of other pituitary hormones (e.g. change in appearance and interdental spacing in acromegaly)

Question 6

what are the investigations for hyperprolactinaemia?

Answer 6

• serum prolactin
• hCG
• TFTs
• U&Es
• PFTs
• MRI pituitary

Question 7

what is the management of symptomatic drug-related hyperprolactinaemia?

Answer 7

• physiological and drug-related hyperprolactinaemia do not typically require treatment
• in symptomatic drug-related hyperprolactinaemia, stopping the causative drug should be considered

Question 8

what is the management of prolactinoma?

Answer 8

• dopamine agonist (e.g. cabergoline, bromocriptine)
• endoscopic transsphenoidal surgery (ETSS)
• radiotherapy

Question 9

what are the long-term complications of hyperprolactinaemia?

Answer 9

hypogonadism secondary to hyperprolactinaemia can lead to:
- infertility
- erectile dysfunction
- osteoporosis

Question 10

what is pituitary apoplexy?

Answer 10

• patients with a pituitary mass causing elevated prolactin may suffer from acute pituitary failure due to haemorrhage or infarction of the pituitary gland (e.g. pituitary apoplexy)
• this is characterised by a sudden onset of neurological symptoms such as headache, visual disturbances and cranial nerve palsies