20. Pituitary tumors – acromegaly, prolactinoma

Question 1

what is the etiology of acromegaly ?

Answer 1

pituatory adenoma

GNRH hypersecretion in hypothalamus

Overproduction of GH → abnormally high serum IGF-1 levels → overstimulation of cell growth and proliferation

5perent can be familial 
McCune albright 
MEH type 1 
carney syndrome 
FIPA - familal isolated pituatory adenomas

Question 2

signs and symtpoms of am ?

Answer 2

Tumor mass compresses neighboring structures (e.g., optic chiasm) → symptoms of mass effect
local mass effects - headache
Bitemporal hemianopsia
opthalmoplegia

inceased size of fortnal sinuses

prominet supraorbital ridges

nose enlargmnet

downward and forward growth of mandile

degenrative arthritis

cardiomegaly = hypertension
LVH
arrhythmia
= major cause of death

, macroglossia with fissures, obstructive sleep apnea

Impaired secretion of other pituitary hormones, especially gonadotropins → ↓ LH and FSH → ↓ estrogen and testosterone
women : Oligomenorrhea, secondary amenorrhea, galactorrhea, vaginal atrophy
♂: Erectile dysfunction, decreased libido, ↓ testicular volume

Question 3

what is the diagnosis of AM?

Answer 3

basal fasting growth hormone levels
more than 2,5ng/ml
serum insulin growth factor 1

glucose oral administration of 75g glucose = cause reduction of growth hormones to less than 1ng/ml in 60 minutes

in acromgealy they can increase decrease or show no change but they do not decrease to less than 1ng/ml

MRI = for tumors

Question 4

treatment of AM?

Answer 4

Surgery
Transsphenoidal adenomectomy

Surgical debulking (in patients with parasellar disease and inoperable tumors)

Medication
Somatostatin analogs (e.g., octreotide, lanreotide) 

Dopamine agonists (e.g., cabergoline): reduce tumor size and GH secretion

GH receptor antagonists (e.g., pegvisomant)

========
stereotactic radiosuregry for tumors confined to the sella

Question 5

what increases prolactins fromthe anterioir pituatory gland ?

Answer 5

from anterioir pirtuaory
thyrotropin releasing hormone

vasopressin from poserioir pituory

hypothalamus oxytocixn

angiotensin two

antagonis = dopamine

Question 6

what is the pathophysiological consequence of high prolactin release

Answer 6

increase dopamine to stop this prolactin

prolactin high levsl aslo cause
an decreases GnRH = FSH AND LH DECREASE

Question 7

what are the signs and symptoms ?

Answer 7

local mass effect = headache
visua disturbances

amenorrhea 
oligomenorrhea 
infertility 
decreased libido 
galactorrhea 
osteoperosis
hypogonadism 

for men 
decreased libido 
gynecomastea 
oteopnea 
= often not diagnosed until late stage mainfestation of headache and visual impairment
impotence 
premature ejaculation

Question 8

what is the diagnosisi for woemn in prolactinoma ?

Answer 8

serum prolactin levels 1 hour after waking up or after having food
and repeated in another day
prolactin blood level is permanently > 200 ng/mL
this particular type of hormone also closely correlates with the size of the tumor

Measure prolactin blood level after administering either metoclopramide (stops inhibition of prolactin secretion) or TRH (physiological stimulus). : prolactin levels remain the same = prolactinoma

MRI
less than 10 mm microprolactinoma
more than 10 mm macropolactinoma

Question 9

what is the treatmnet for prolactinoma ?

Answer 9

Asymptomatic microprolactinoma: no treatment

symptomatic :
dopamine agonist :
bromocriptine and cabergoline

Transsphenoidal surgery (± radiotherapy) is generally reserved for very large tumors or prolactinomas that increase in size despite pharmacological therapy

Question 10

side effects of dopamine agonists ?

Answer 10

(dose-dependent)
 Nausea,vomiting,mouthdryness,constipation
Orthostatic hypotension

In chronic use → cytolitic effect