Pituitary Path Flashcards
describe the physical findings of ICP
- HA, NV
- bradycardia
- shallow breathing
- HTN
- papilledema
bilateral temporal hemianopsia is due to
compression of the optic chiasm
result of mass effect
how will pituitary apoplexy present?
s/o excruciating HA, diplopia and hypopituitarism
what is the most common type of secretory pituitary adenoma?
prolactinoma/lactotroph
describe the presentation of prolactinoma in females
galactorrhea and amenorrhea
also: decreased libido, mass effect (more in men), and infertility
describe the presentation of prolactinoma in men
decreased libido, HA, and mass effect
also: decreased sperm count
what has this histology?
- stomal hyalinization with psammoma bodies
- stains for PIT-1
prolactinoma
“pituitary stone” from the calcification
describe the treatment for prolactinoma
dopamine agonists:
bromocriptine, cabergoline
surgery
name other causes (5) of hyperprolactinemia in the absence of adenoma
- pregnancy
- lactation/nipple stimulation
- loss of DA —> lactotroph hyperplasia
- renal failure
- hypothyroidism
loss of DA can cause lactotroph hyperplasia, leading to hyperprolactinemia in the absence of adenoma
how can loss of DA occur?
- damage to neurons via truama, stroke
- drugs (verapamil; antipsychotics, antidepressants; metoclopramide)
- mass
renal failure can leading to hyperprolactinemia in the absence of adenoma
how?
producing excess prolactin yet excreting less because of the decreased clearance
hypothyroidism can lead to hyperprolactinemia in the absence of adenoma
how?
increased TRH can stimulate PRL production due to a cross-reaction
what is the LAM
lactational amenhorrhea method
if a woman is breast feeding, a state of elevated PRL, she will maintain anovulation
how do you diagnose a somatotroph?
- increased GH
- increased IGF-1
- oral glucose tolerance test (lack of GH suppression)
describe the features of acromegaly in adults
- jaw, spaid-like hands, feet
- tongue
- visceral organs (cardiac failure)
secondary DM is present in somatotrophs
how?
GH induces liver gluconeogenesis
GH induces somatomedin (IGF), describe the effects
- increased linear growth of bone
- increased organ size
- decreased adiposity
- increased lean body mass
with respect to somatotrophs, five elements cause negative inhibition of the hypothalamus. what are they?
- GHRH*
- GH*
- Glucose
- FFA
- somatomedin/IGF*
*negative feedback
with respect to somatotrophs, what does the hypothalamus secrete to inhibit the pituitary gland and release of GH?
somatostatin
in the world of somatotrophs
does somatomedin inhibit the hypothalamus or the pituitary gland?
IGF has negative feedback to both
what is the treatment for somatotrophs?
- somatostatin analog: octreotide
- GH receptor antagonists
- surgery
40% of somatotrophs have what mutation?
GNAS
somatic mutation
what does GNAS encode?
Gs-alpha
name the chromosome location of GNAS
20q13
what causes cushing disease?
corticotroph adenoma
it will present with cushing syndrome because that is hypercortisolism and all of its baggage: central obesity, diabetes, vellous hirsutism, adrenal hyperplasia, violaceous striate, thin skin…the list goes on
but only corticotroph adenoma can cause cushing disease
PAS+
corticotroph adenoma
POMC is precursor to ACTH and B-endorphin
SF-1, GATA-2
gonadotrophs
paraneoplastic cushing syndrome
name the three possible ectopic causes
- small cell carcinoma of the lung
- pancreatic carcinoma
- neural tumor
elevated ACTH in the inferior petrosal sinus means the source is
pituitary
elevated plasma cortisol
suppressed corticotropin level
(no suppression on dexamethasone)
adrenal tumor or hyperplasia
diagnose with CT; will have low ACTH after CRH stimulation test b/c ACTH-independent
elevated plasma cortisol
elevated corticotropin level
suppression on high-dose dexamethasone
corticotroph adenoma/cushing disease
diagnose with MRI; elevated ACTH after CRH stimulation b/c ACTH-dependent
elevated plasma cortisol
elevated corticotropin level
no suppression on high-dose dexamethasone
ectopic source
(small cell lung carcinoma, pancreatic carcinoma, neural tumor–all paraneoplastic)
diagnose with MRI; elevated ACTH after CRH stimulation b/c ACTH-dependent
describe the treatment for corticotroph adenoma
- somatostatin analogs
- bromocriptine
- surgical excision
(corticotroph adenomas express DA receptors and somatostatin receptors)
how will a patient with Nelson syndrome present?
hyperpigmentation as a result of greatly elevated ACTH (a-MSH stimulated by ACTH)
- pre-existing corticotroph microadrenoma grows b/c no inhibition from adrenal corticosteroids
TPIT
corticotroph
USP8 mutation
corticotroph; results in EGFR upregulation
somatic mutation
AIP
somatotroph
familial mutation
well-circumscribed
erodes bone
bleed
adenoma
poorly circumscribed
invade brain
aggressive adenoma
where does pituitary carcinoma metastasize?
throughout the brain
v. rare
rupture of what can result in inflammation of the pituitary or meningitis?
rathke’s cleft cyst
ciliated columnar epithelium
10 yr old with growth retardation d/t hypopituitarism likely has
adamantinomatous craniopharyngioma
WNT mutation —> B-catenin
65 yr old with ICP or hypopituitarism, consider
papillary craniopharyngioma
solid, multiloculated/cystic mass impinging on optic chiasm describes
craniopharyngioma
cranipharyngiomas are derived from
rathke’s pouch
histology showing:
squamous epithelium
wet keratin
dystrophic, calcified cyst
craniopharyngioma
CSF leaking into the sella causes
primary sella syndrome – compresses the pituitary
usually an obese mxparous woman with vision changes
expansion of the pituitary resulting in infarct causes
secondary empty sella syndrome
postpartum woman presents with failure of lactation, loss of pubic hair, fatigue, and hypotension
sheehan syndrome – necrosis of anterior pituitary
describe the pathogenesis of loss of pubic hair in sheehan syndrome
no LH from AP, so no androgens to produce pubic hair
is the anterior pituitary mostly dependent on arterial or venous supply?
venous
- increased serum osmolality, hypernatremia
- dilute, excessive urine
- polyuria
diabetes insipidus – central or nephrogenic
if the kidney responds to DDAVP with increased water retention and increased urine sodium/osmolality, what kind of diabetes insipidus is it?
central DI
- mental status changes, seizures
- muscle weakness
- hyponatremia
- hypernatriuria
SIADH
name the causes of SIADH
- small cell carcinoma of the lung
- TBI/SAH
- SSRIs
- pulmonary infection
- COPD
- cyclophosphamide
name two drugs that cause nephrogenic DI
lithium, demeclocycline
