Pituitary Flashcards
most common types of pituitary adenomas
1 - prolactinoma
2 - nonfunctional gonadotroph adenoma
incidence of central DI in pituitary adenomas
essentially zero
pituitary lesion with DI should raise concern for what
metastatic lesion
craniopharyngioma
hypophysitis
sarciodosis
postpartum female with agalactia, fatigue
Sheehan syndrome
T value below this should prompt MRI pituitary central hypogonadism
< 150 pg/dL
typical order of pituitary hormone deficiency after cranial irradiation
GH
FSH/LH
ACTH
TSH
cause of Sheehan syndrome
typically massive uterine hemorrhage/hypovolemia
treatment of pituitary apoplexy
empiric hydrocortisone
neurosurgical consult
cause of empty sella syndrome
intrasellar herniation of the suprasellar subarachnoid space with compression of the pituitary gland producing a remodeling of the sella
cause of mild prolactin elevation in empty sella syndrome
stalk stretching
functional causes of pituitary insufficiency
exogenous steroids exogenous testosterone hypothalamic amenorrhea due to exercise, anorexia critical illness opiates
antiepileptics increase catabolism of which steroids?
dexamethasone/prednisone > hydrocortisone
immunohistochemical staining for corticotroph tumors
T-Pit
immunohistochemical staining for gonadotroph tumors
SF-1
immunohistochemical staining for thyrotrophs, somatotrophs, and lactotroph tumors
Pit-1
what is the significance of silent or plurihormonal pituitary tumors?
aggressive behavior
invasive
high rates of recurrence
can progress to functional tumors over time
are pituitary tumors heritable
< 5% are heritable
MEN1, MEN4
FIPA
Succinate dehydrogenase mutations (SDH)
conditions that can cause “pseudotumor” of the pituitary gland
severe hypothyroidism
puberty
pregnancy
medical therapy for nonfunctional adenomas
cabergoline
Not FDA approved but some studies that show it may be beneficial
rate of growth of pituitary adenomas
typically 1-2mm per year
in what percentage of patients with pituitary insufficiency related to NFA will there be improvement or normalization of pituitary hormone function postoperatively?
15-30%
how long after surgery to re-test pituitary function?
6-12 weeks
equivalent doses of subq/IV, nasal, and oral desmopressin
1mcg
10mcg
100mcg
most common sodium abnormality after pituitary surgery
SIADH
management of postoperative DI
free water (by mouth if thirst mechanism intact) PRN desmopressin (usually transient) rarely permanent - if so, will need to go home on desmopressin
nadir of SIADH post surgery
5-9 days
fluid restriction instructions for post pituitary surgery patients on discharge
1-1.5L of fluids/day
sodium level in 7 days
ddx of post TSS hyponatremia
SIADH
hypothyroidism
adrenal insufficiency
typical pattern of pituitary hormone deficiency
GH FSH/LH TSH ACTH Prolactin
how common are pituitary carcinomas
extremely rare. < 0.2% or pituitary carcinomas
most common manifestation of pituitary metastatic disease
DI
only pituitary hormone primarily regulated by negative feedback
prolactin (constant negative feedback via dopamine)
effect of estrogen on prolactin level
increases
physiologic states with elevated prolactin
pregnancy, lactation
stress, exercise, nipple stimulation
how high can prolactin levels go in pregnancy
200-300 ng/mL
definition of galactorrhea
discharge of milk from the breast not associated with pregnancy or lactation
can cabergoline be used in pregnancy
probably safe, but stop if possible
when to re-image macroprolactinoma after starting cabergoline
3 months
how long for prolactin to normalize on dopamine agonist therapy?
weeks-months
how long is medical therapy required for prolactinomas?
usually lifelong, but can try to stop as ~20% of patients will be cured
rhinorrhea in a pt with macroprolactinoma after starting on cabergoline
CSF leak from rapid shrinkage
indications for surgery on macroprolactinoma
intolerance to medical therapy
unresponsive to medical therapy
young female desiring pregnancy (to avoid medical therapy while pregnant)
normal function of GH in children and adults
children - linear growth
adults - metabolic effects
does GH directly affect peripheral tissues?
Very little. Most effects are mediated thru IGF-1.
single biggest clue in examining a patient suspected of having acromegaly?
old photographs
metabolic effects of acromegaly
HTN DM cardiomyopathy OSA 30% higher mortality rate
which pituitary hormones are glycoproteins
FSH
LH
TSH
Ddx for transient increase in serum T4 and normal/elevated TSH
Took Lt4 right before lab test (noncompliant)
other meds (amiodarone, amphetamines, heparin, NSAIDS)
Acute psychiatric illness
Acute liver disease
Ddx for patients with permanent increase in serum T4 and normal/elevated TSH
TSHoma thyroid hormone resistance HAMA antibodies (heterophile antibodies) FDH (familial dysalbuminemic hyperthyroidism) excessive TBG
how to differentiate between TSHoma and resistance to thyroid hormone
elevated alpha subunit - TSHoma
elevated SHBG - TSHoma
T3 suppression test - TSHoma won’t suppress
treatment of choice for TSHoma
surgery
medical therapies for TSHoma
octreotide
thionamides/bblockers preoperatively
what can happen to the pituitary gland in longstanding hypothyroidsm
pseudotumor due to pituitary hyperplasia
is thyroid hormone resistance typically de novo or hereditary
hereditary, autosomal dominant
in functional pituitary gonadotropinomas, is the FSH or LH typically higher
FSH
which pituitary hormones are commonly elevated in ESRD patients
prolactin (avg 65 ng/mL, range 48-195)
GH (increased peripheral tissue resistance)
pt with panhypopit is started on GH. Free t4 concentration drops. Reason?
GH increased conversion from T4 to T3.
effect of testosterone supplementation on TBG
decreased TBG (and subsequent increase in free t4)
female with panhypopit on oral estradiol and GH who wants to change to transdermal estradiol. what to do with GH dose?
decrease by 50%. women on oral e2 require 2-3x dose of GH replacement, so changing to transdermal requires dose reduction
female pt with hx of metastatic breast ca who presents with adrenal crisis and then gets hypotensive with brisk UOP after steroid replacement. Cause?
unmasking of central DI after starting on glucocorticoids
