pituitary & hypothalamus Flashcards
what is hypopituitarism
low functioning pituitary gland
*either a problem with the hypothalamus upstream OR pituitary gland itself
What are the causes of hypopituitarism
Hypothalamus or pituitary lesions
*pituitary adenoma
What type of adenoma is most common cause of hypopituitarism
prolactinomas
What age group is at highest risk for pituitary adenomas
30-40
*can be inherited
How does hypopituitarism present
Headaches /visual changes (mass effect)
-fatigue, dizziness, hypotension, confusion, polydipsia
If someone has GH deficiency, how will they present
short stature
micropenis
central obesity
hyperlipidemia
reduced muscle/bone mass
CV dysfunction
If someone has a gonadotropin deficiency, how will they present
FSH and LH deficiency
*hypogonadism and infertility, impaired/absent puberty, sexual dysfunction, loss of secondary male characteristics
how is hypopituitarism diagnosed
through evaluation of hormone levels or downstream effects
-evaluation of GH level
How can you evaluate GH levels
Via stimulation testing
*no GH increase w/ exercise
*no GH increase with glucagon
How can you test for adrenal deficiency
Low AM serum cortisol
Low serum ACTH
Low serum DHEA
Low ACTH w/ cosyntropin stimulation
What type of imaging is done to assess the pituitary
MRI of hypothalamus
Who will have an MRI of their hypothalamus to assess the pituitary
Men>16 with low LH & serum testosterone.
2+ pituitary hormone deficiencies
Persistent hyperprolactinemia
symptoms of mass effect
What will be seen on imaging with hypopituitarism
Distinct mass
generalized pituitary enlargement
thickening of pituitary stalk
How do you treat hypopituitarism
Resection of tumors or other masses
dopamine agonist in prolactinomas (first line)
radiation as a last line
What are the dopamine agonists used for prolactinomas
bromocriptine or cabergoline
If the pituitary gland is removed, what does the patient need to take for the rest of their life
-Glucocorticoid replacement (hydrocortisone)
-levothyroxine AFTER glucocorticoid initiation
-Gonadotropin replacement
-hGH replacement
what is a pituitary adenoma
Benign tumor arising from any one of the pituitary cell types
*most common cause of hypo and hyperpituitarism in adults
What are the classifications of pituitary adenomas
Micro vs Macro
Functioning vs Non-functioning
What is a functioning pituitary adenoma
secretion of hormones by the tumor
What is a macro adenoma
> 1cm diameter -> generally get mass effect and hypopituitarism
What is the test of choice for a pituitary adenoma
MRI with gadolinium
What is a secondary hormone dysfunction workup
Basal prolactin
insulin like growth factor
24hr urinary free cortisol
FSH & LH
Thyroid function test
What are acidophils
GH
Prolactin
What are basophils
TSH
LH/FSH
ACTH
If the pituitary adenoma is small, how do you treat
Annual MRI to monitor
*if no growth, can reduce frequency
How do you treat a macro adenoma
Resection via a transsphenoidal approach
+/- radiation
What medications can inhibit a pituitary adenoma
Somatostatin
dopamin
*both inhibit
what is the most common pituitary hormone hypersecretion syndrome
Hyperprolactinemia
What are the underlying causes of hyperprolactinemia
Physiologic: exercise, inherited, sleep
Pharmacologic: amphetamines, opioids, nicotine, TCA, SSRI
Pathologic: Acromegaly, Hypothalamic disease, hypothyroidism, tumors
What is a normal prolactin level in males
<20ng/mL
What is a normal prolactin level in non-pregnant women? Pregnant?
<25ng/mL
40-800ng/mL
What prolactin levels are indicative of a prolactinoma (excluding pregnancy)
> 200ng/mL
How do you workup hyperprlactinemia
Evaluate for underlying causes (test all other pituitary hormones)
If no physiological change or pharmacologic cause -> MRI
What is gigantism
excessive growth in childhood, prior to physical closure (long bones)
What is acromegaly
excessive growth after physical closer (no long bone involvement)
-hands
-feet
-head
How do you test for acromegaly and gigantism
Random serum IGF-1
*if normal= ruled out
How is gigantism physically differentiated from acromegaly
They have a tall stature and delayed puberty, where as acromegaly the bones would be wider than normal
What is the workup for acromegaly and gigantism
Fasting, no exercise, and no illness
-serum IGF-1
-prolactin level
-Glucose
-LFTs,BUN,creatinine
-serum calcium
-free T4 and TSH
What kind of imaging can be done for acromegaly and gigantism
pituitary MRI
Skull xray (enlarged sella, thick skull)
Xray of hand and feet
What will be seen on the hand and feet X-rays with acromegaly
tufting of phalanges (spade looking)
Enlarged calcaneous
What is the treatment of choice for acromegaly and gigantism
Transsphenoidal resection
What is the most common skeletal dysplasia
achondroplasia
What type of genetic disease is achondroplasia
Autosomal dominant
fibroblast GF receptor 3 gene
*if homozygous = Letha;
What are some clinical features of achondroplasia
Disproportionate short stature
large head
delayed motor development
short fingers
exagg. lumbar lordosis
prominent forehead
How can achondroplasia be confirmed
genetic testing
+FGFR3 mutation
What complications arise from achondroplasia
recurrent OM
OSA
Obesity
spinal stenosis
narrow foramen magnum (can cause hydrocephalus)
What is Diabetes insipidus
deficiency in ADH (vasopressin) - posterior pituitary
loss of renal H2O reabsorption = polyuria
What are the types of diabetes insipidus
Central (ADH deficiency)
- primary cause being no lesion
Nephrogenic (kidney just isn’t responding to ADH)
What is the presentation of diabetes insipidus
intense thirst
cravings for ice water
polyuria
enuresis
If urine has high volume and low specific gravity, how is it classified
dilute
What testing can rule of DI
24hr urine collection with less that 2L collected
How do you treat diabetes insipidus
DDAVP (desmopressin)
Nasal, SQ or IV (nasal / oral preferred)
start low and go slow
What is SIADH
Inappropriate release of ADH
Who is at increased risk for DI
Pituitary tumor
Craniotomy
head injury
What causes SIADH
Central (metabolic, CNS, psychiatric, iatrogenic)
Lungs (infection, mechanical, tumors- specifically small cell)
How does SIADH present
decreased fluid output even with adequate or increased intake
*fluid overload-> edema, hyponatrema, BP
What would workup show with SIADH
Serum hyponatremia
hypoosmolality
increased urine sodium concentration
normal thyroid/adrenal function
What is the treatment of SIADH
Treat underlying causes
fluid restriction***
if severe -> IV sodium chloride
