functional pituitary adenomas

Question 1

definition

Answer 1

adenoma of the pituitary gland which does secrete hormones

Question 2

types of functional pituitary adenomas

Answer 2

• prolactin secreting adenoma (most common type) which causes hyperprolactinaemia
• growth hormone secreting adenoma which in children causes GIGANTISM and in adults causes ACROMEGALY
• adrenocorticotrophic releasing adenoma which causes CUSHINGS DISEASE
• thyroid stimulating hormone secreting adenoma (rare) causing secondary hyperthyroidism
• FSH and LH secreting adenomas (extremely rare) which cause reproductive dysfunction

Question 3

hyperprolactinemia definition

Answer 3

hyperprolactinemia means increased prolactin levels in the blood

Question 4

causes of hyperprolactinema subgroups

Answer 4

• physiological
• drugs
• pathological

Question 5

physiological causes of hyperprolactinemia

Answer 5

breast feeding, pregnancy and stress

Question 6

drugs that cause hyperprolactinemia

Answer 6

• anti-psychotics and anti-emetics as they are dopamine receptor antagonists
• anti-depressant which are selective serotonin reputake inhibitors
• cocaine

Question 7

pathological causes of hyperprolactinemia

Answer 7

• prolactinoma
• damage to pituitary stalk
• hypothyroidism

Question 8

symptoms of a prolactinoma are

Answer 8

different in men and woman and tend to present because prolactin inhibits the affects of FSH and LH on the ovaries and the testes

Question 9

in females prolatinoma tends to be a

Answer 9

microadenoma

Question 10

symptoms of proalctinoma in females

Answer 10

ammenorhoea

galactorrhea

Question 11

in males prolactinoma tends to be a

Answer 11

macro adenoma

Question 12

symptoms of prolactinoma in males

Answer 12

• bitemporal hemianopsia (no other cause of hyperprolactinamei except a prolactinma would cause this)
• gynaecomastia
• reduced libido and erectile dysfunction

Question 13

investigations for prolactinoma

Answer 13

• prolactin levels

- MRI

Question 14

MANAGEMENT OF PROLACTINOMA

Answer 14

DOPAMINE AGONIST (carbergoline)

Question 15

what does carbergoline do

Answer 15

shrinks the tumour by around one third and also normalises prolactin levels in more than 95% of cases

Question 16

acromegaly is nearly always caused by a

Answer 16

functional adenoma which secretes growth hormone

Question 17

acromegaly can only occur in

Answer 17

adults (who’s growth plates are fused) if a growth hormone secreting pituitary adenoma occurs in children (who’s growth plates have not yet used) it causes GIGANTISM

Question 18

features of acromegaly

Answer 18

• prognathism= protrusion of the lower jaw
• thickened soft tissues of the jaws, palms and fingers
• excessive sweating
• deepened husky voice
• hyper pigmentation
• teeth gapping
• gynaecomastia and galactorrhea

Question 19

hands are feet in acromegaly are said to be

Answer 19

spade shaped

Question 20

complications of acromegaly

Answer 20

• hypertension and cardiomegaly can cause congestive heart failure
• headaches caused by increased blood flow through the head due to the affects of growth hormone on the vasculature
• diabetes mellitus
• colonic polyps and colon adenocarcinoma

Question 21

headaches in acromegaly are caused by

Answer 21

the increased blood flow through the head caused by the affect of growth hormone on the vasculature not because of the adenoma itself

Question 22

diagnosis of acromegaly

Answer 22

• IGF-1 LEVELS

- glucose tolerance test: suppression test

Question 23

glucose tolerance test

Answer 23

give 75g oral glucose

• in normal people growth hormone levels should all to less than 0.4 because increased blood glucose has a negative feedback affect of the hypothalamus and anterior pituitary
• in those with acromegaly growth hormone levels stay at 1 or above and may even rise this is because the negative feedback has nor affect because the tumour is producing growth hormone

Question 24

if glucose tolerance test suggest acromegaly what should you do

Answer 24

get an MRI for definitive diagnosis

Question 25

management of acromegaly 1st line

Answer 25

transphenoidal resection

Question 26

success rates of transphenoidal resections

Answer 26

• 90% success rate for micro adenoma

- 50% success rate for macroadeomas

Question 27

post-surgery

Answer 27

the glucose tolerance test is repeated
if growth hormone level less than 0.4= successful surgery
if growth hormone greater than 1= unsuccessful resection and requires further drug therapy or radiotherapy

Question 28

1st line drug therapy used in acromegaly

Answer 28

somatostatin analogies: ocreotidem lanreotide as they reduce secretion of growth hormone from the anterior pituitary and cause shrinkage of the tumour

Question 29

side effects of somatostatin analogous

Answer 29

gastritis and gallstones

Question 30

2nd line drug therapy

Answer 30

dopamine agonist; carbergoline can be useful if the adenoma also secretes prolactin but is not that successful

Question 31

last line drug therapy

Answer 31

growth hormone antagonist= pegvisomant which binds directly to growth hormone receptors blocking growth hormone activity, IGF-1 falls but growth hormone may paradoxically rise as the negative feedback affect is lost

Question 32

why is pegvisomant last line

Answer 32

85% response rate but extremely expensive, i.e. NHS is poor