functional pituitary adenomas Flashcards
definition
adenoma of the pituitary gland which does secrete hormones
types of functional pituitary adenomas
- 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
hyperprolactinemia definition
hyperprolactinemia means increased prolactin levels in the blood
causes of hyperprolactinema subgroups
- physiological
- drugs
- pathological
physiological causes of hyperprolactinemia
breast feeding, pregnancy and stress
drugs that cause hyperprolactinemia
- anti-psychotics and anti-emetics as they are dopamine receptor antagonists
- anti-depressant which are selective serotonin reputake inhibitors
- cocaine
pathological causes of hyperprolactinemia
- prolactinoma
- damage to pituitary stalk
- hypothyroidism
symptoms of a prolactinoma are
different in men and woman and tend to present because prolactin inhibits the affects of FSH and LH on the ovaries and the testes
in females prolatinoma tends to be a
microadenoma
symptoms of proalctinoma in females
ammenorhoea
galactorrhea
in males prolactinoma tends to be a
macro adenoma
symptoms of prolactinoma in males
- bitemporal hemianopsia (no other cause of hyperprolactinamei except a prolactinma would cause this)
- gynaecomastia
- reduced libido and erectile dysfunction
investigations for prolactinoma
- prolactin levels
- MRI
MANAGEMENT OF PROLACTINOMA
DOPAMINE AGONIST (carbergoline)
what does carbergoline do
shrinks the tumour by around one third and also normalises prolactin levels in more than 95% of cases
acromegaly is nearly always caused by a
functional adenoma which secretes growth hormone
acromegaly can only occur in
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
features of acromegaly
- 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
hands are feet in acromegaly are said to be
spade shaped
complications of acromegaly
- 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
headaches in acromegaly are caused by
the increased blood flow through the head caused by the affect of growth hormone on the vasculature not because of the adenoma itself
diagnosis of acromegaly
- IGF-1 LEVELS
- glucose tolerance test: suppression test
glucose tolerance test
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
if glucose tolerance test suggest acromegaly what should you do
get an MRI for definitive diagnosis
management of acromegaly 1st line
transphenoidal resection
success rates of transphenoidal resections
- 90% success rate for micro adenoma
- 50% success rate for macroadeomas
post-surgery
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
1st line drug therapy used in acromegaly
somatostatin analogies: ocreotidem lanreotide as they reduce secretion of growth hormone from the anterior pituitary and cause shrinkage of the tumour
side effects of somatostatin analogous
gastritis and gallstones
2nd line drug therapy
dopamine agonist; carbergoline can be useful if the adenoma also secretes prolactin but is not that successful
last line drug therapy
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
why is pegvisomant last line
85% response rate but extremely expensive, i.e. NHS is poor
