Pituitary Non-functioning adenomas and Prolactinomas

Question 1

what is the definition of a microadenoma and macroadenoma pituitary tumours

Answer 1

microadenoma =1cm

macroadenoma >1cm

Question 2

what complications can arise from a non-functioning pituitary adenoma being too big

Answer 2

compression of optic chiasma, compression of other structures(eg cranial nerves 3,4,6)

Question 3

what complications can arise from a non-functioning pituitary adenoma being too-small

Answer 3

hypoadrenalism, hypothyroidism, hypogonadism, GH deficiency, diabetes insipidus

Question 4

what is the most common visual defect caused by pituitary tumours

Answer 4

bitemporal hemianopia(black areas of peripheral visual field), due to optic chiasma compression

Question 5

what management can be used for non-functioning pituitary adenomas

Answer 5

transphenoidal surgery, replace hormones

Question 6

what is a prolactinoma

Answer 6

tumour of the pituitary gland that produces prolactin

Question 7

what are the physiological causes of increased prolactin secretion

Answer 7

pregnancy, breast feeding, stress, sleep

Question 8

what drugs can act to increase prolactin secretion

Answer 8

dopamine antagonists(eg antiemetics), antipsychotics, antidepressants

Question 9

how is prolactin normally controlled

Answer 9

dopamine secreted by hypothalamus suppresses prolactin secretion from pituitary

Question 10

what are some of the pathological causes of increased prolactin secretion

Answer 10

hypothyroidism, pituitary stalk lesions(iatrogenic, road accident), prolactinoma

Question 11

why do pituitary stalk lesions cause increased prolactin secretion

Answer 11

because this blocks dopamine getting to the pituitary to suppress prolactin, so prolactin continues to be secreted

Question 12

what are the clinical signs and symptoms associated with prolactinoma in females

Answer 12

EARLY presentation, galactorrhoea(30-80%), menstrual irregularity, ammenorrhoea, infertility

Question 13

what are the clinical signs and symptoms associated with prolactinoma in males

Answer 13

LATE presentation, impotence, visual field abnormal, anterior pituitary malfunction

Question 14

what investigations are done for prolactinoma

Answer 14

serum prolactin conc.(too high?), MRI pituitary, visual fields, pituitary function tests

Question 15

what features are looked for in MRI of prolactinoma

Answer 15

pituitary enlarged, microprolactinoma(<1cm), macroprolactinoma(>1cm), pituitary stalk, optic chiasma

Question 16

what type of drug is used to treat prolactinoma and give the one used most

Answer 16

dopamine agonists, usually Cabergoline(Dostinex) once/twice per week oral

Question 17

what are the possible side effects of dopamine agonists

Answer 17

nausea/vomiting, low mood

Question 18

how successful are dopamine agonists in treating prolactinoma

Answer 18

very, 96% prolactinoma normalised, also very good at regaining menstruation, pregnancy rate and tumour shrinkage