pituitary lecture 1 and 2 Flashcards
what would class a tumour as a microadenoma?
tumour that is 1 cm or less
what would class a tumour as a macroadenoma?
if the tumour is greater than 1 cm
what are physiological causes for raised prolactin?
- breast feeding
- pregnancy
- stress
what drugs may raise prolactin?
- dopamine antagonists e.g. metoclopramide
- antipsychotics e.g. phenothiazines
- antidepressants eg TCA, SSRIs
- Other: oestrogen, cocaine
what investigations would you do if you suspected prolactinoma?
- serum prolactin (would be high)
- MRI pituitary (would be too big)
- check visual fields (for bitemporal hemianopia)
- pituitary function tests (to see if other hormones are affected, in microprolactinoma it is unlikely to affect them but macroprolactinoma might)
what treatment is given for prolactinoma?
USE DOPAMINE AGONISTS!!
-Cabergoline (Dostinnex) is usually used due to least side effects, it is given once to twice per week orally
Other dopamine agonists:
- bromocriptine (3x per day orally)
- quinagolide (1x per day orally)
what are side effects of dopamine agonists?
- nausea/vomiting
- low mood
- fibrosis of heart valves/ retroperitoneal (however patients who are on meds for prolactinoma have such low dosage they wont experience this)
what effects do dopamine agonists have on prolactinoma?
- normalise prolactin levels
- tumour shrinkage
what causes acromegaly?
GH excess
how does acromegaly present?
- bones increase in size
- thickened soft tissues (skin, large jaw, sweaty, large hands)
- snoring/ sleep apnoea (due to thickened nasopharynx)
- hypertension
- cardiac failure
- headaches
- DM
- Hypopituitarism
- Visual field disturbances
- early CV death
- colonic polyps and colonic cancer
how is acromegaly diagnosed?
Gold standard= GTT suppression test, give 75g oral glucose and check GH every half hour for 2 hours, normally GH < 0.4 mg/l so if it doesn’t do this it suggests acromegaly
Blood serum:
-increased IGF1 (sometimes it is not that raised so dont always use this test)
what investigations should be done if there’s suspected acromegaly?
- GTT suppression test, if GH> 0.4mg/l then acromegaly is present
- check visual fields
- CT or MRI pituitary gland
- pituitary function test (to check the other hormones)
what is the treatment for acromegaly?
PITUITARY SURGERY = first line (90% cure if microadenoma and 50% cure if its macroadenoma)
DRUGS= second line
- Somatostatin analogues: Sandostatin and lanreotide
- Dopamine Agonists: Cabergoline (only works in 10-15% of patients)
- GH Antagonist: pegvisomant (most effective but expensive so last line)
-radiotherapy alone= third line (25% success at 3 years)
what are some examples of somatostatin analogues?
- sandosatin LAR
- lanreotide autogel
- pasireotide LAR
what effect do somatostatin analogues have on GH?
they reduce GH in most patients
what effect do somatostatin analogues have on the tumour?
- they shrink the tumour (by 30-60%)
- however the tumour will re expand 6 weeks after stopping somatostatin analogues
how long does it take for somatostatin analogues to work?
6-12 months
what are side effects of somatostatin analogues?
-local stinging
Short term:
- flatulence
- diarrhoea
- abdominal pain
long term:
-gall stones
what type of injection is Sandostatin LAR?
IM injection
what type of injection is pasireotide LAR?
IM injection
what type of injection is lanreotide autogel?
SC injection
what dose is Sandostatin LAR given?
1-30mg once a month
when would you choose to use a dopamine agonist in acromegaly?
- sometimes patients with acromegaly secrete GH and prolactin
- would use a dopamine agonist
what is an examples of a GH antagonist?
pegvisomant
