disorders pituitary gland Flashcards
pituitary is attached to the hypothalamus via a stalk called
the infundibulum
Pituitary gland lies where in the body
- lies near optic chiasm
What is the most common type of sellar mass
pituitary adenoma
sellar masses typically present in one or a combination of what 3 ways
- with neurologic symptoms, such as visual impairment or HA
- as an incidental finding on MRI
- with hormonal abnormalities
What visual defect is most common with sellar masses
bitemporal hemianopsis
In a lactotroph ademoma, check serum levels
prolactin
In a somatotroph ademoma, check serum levels
- IGF-1
- GH
In a thyrotropin ademoma, check serum levels
serum TSH
In a corticotroph ademoma, check levels
- 24 hr urine cortisol
- serum ACTH
- serum cortisol
If patient has hormonal hyposecretion (caused by hypothalamic or other pituitary lesion, NOT an adenoma) then get what labs
- FSH
- LH
- testosterone, free and total: males
- estradial, free and total: females
- vasopressin
What is hte single best imaging study for pituitary mass
- MRI with and w/o gadolinium
differentiate between a microadenoma and macroadenoma
- microadenoma: < 1 cm
- macroadenoma: > 1 cm
Clincal presentation
- men: low libido, impotence, infertility, gynecomastia, galactorrhea
- female: infertility, oligomenorrhea, amenorrhea
- all: visual disturbances, HA
Prolactinoma (lactrotroph adenoma)
If patient has signs and symptoms of prolactinoma, check these things first
- med use
- cimetidine, methyldopa, verapamil, antidepressants, estrogen will all increase serum prolactin
- pregnant
- h/o renal disease: inability to clear prolactin
Serum prolactin levels greater than is consistent with hyperprolactinemia. Levels greater than is consistent with adenoma
- > 20 ng/mL
- > 200 ng/mL
- as long as pregnancy (-)
Tx of Prolactinoma
-
Bromocriptine: Dopamine agonist
- will shrink tumor to size acceptable for surgery
- Cabergoline: non ergot dopamine agonist
side effects of Bromocriptine
- nausea, constipation, dizziness, HA
What is the most common complication following transphenoidal resection of prolactinoma
- instability of vasopressin leading to SIADH
Growth hormones excess in children and adults leads to what 2 different conditions
- peds: gigantism
- adult: acromegaly
Growth hormone is synthesized in . It is released in large pulses. When is the largest peak
- anterior pituitary
- 1 hr after onset of sleep
What is the most accurate maker for GH
IGF-1
List the stimulators of GH
- GHRH
- sleep
- exercise
- hypoglycemia
- dietary protein
- estradiol
- arginine
List the inhibitors of GH
- somatostatin
- circulating concentrations of GH and IGF-1
- dietary carbohydrates
- glucocorticoids
Acromegaly is most commonly the result of
a somatotroph (growth hormone secreting) pituitary adenoma
clinical presentation
- visual field defects
- LVH, HTN
- organomegaly
- OA of large joints, increasing hat size, ring or shoe size, enlarging gap between teeth
acromegaly
Workup of acromegaly involves
- TSH, GH, IGF-1, CMP, CBC, AM cortisol, ACTH, prolactin, UA, rheumatology panels
- 2 hr glucose tolerance test
what calcium value is consistent with acromegaly
hypercalciuria
explain the 2 hr glucose tolerance test in relation to acromegaly
- if GH level suppresses to < 1 mcg/L during 2 hrs after glucose administration, then acromegaly is excluded
patients with acromegaly are at high risk for
- premature mortality
- insulin resistance
- LVH/CHF
- colon CA
- musculoskeletal abnormalities
What is the most effective tx for rapid reduction of GH in acromegaly
surgical management
Medical managment of acromegaly
- somatostatin analogues
- GH receptor agonist
List the causes of GH deficiency from pituitary dysfunction
- mass
- infarction
- infiltrative
- genetic
List the causes of GH deficiency from hypothalamic dysfunction
- mass
- infiltrative (sarcoidosis)
- trauma
- infection (TB)
List the causes of GH deficiency from iatrogenic
- radiation
- pituitary surgery
- side effect of uncontrolled DM
If patient has any lab abnormalites that point to GH deficiency, need to further confirm with either
- insulin-induced hypoglycemia (stimulation test)
- arginine-growth hormone-releasing hormone **recommended
Management of growth hormone deficiency
- do not treat unless confirmed deficiency
- treat if severe
- recombinant GH
- dose based on weight, SQ once daily in evening
- recombinant GH
Define male hypogonadism. Differentiate between primary and secondary
- impairment of either testosterone or sperm production by testis
- primary: failure of testis (hypergonadotrophic hypogonadism)
- secondary: defect in HPT axis (hypogonadotrophic hypogonadism)
What levels of testosterone, FSH, and LH would you expect to see in
- primary hypogonadism (hyper)
- secondary hypogonadism (hypo)
- a) primary:
- low testosterone
- high FSH, LH
- b) secondary:
- low testosterone
- low/nml FSH, LH
List causes of hypogonadatrophic hypogonadism
- congenital (rare)
- acquired
- hypothalamic: impaired GnRH secretion
- pituitary: suppression of gonadotropins
- GnRH resistance
- hyperprolactinemia
- exogenous steroid
- chronic narcotic
- DM
- pituitary: damage to gonadotroph cells
- sarcoidosis
- hemochromatosis
clinical presentation
- change in hair growth or distribution
- changes in voice
- decreases muscle mass or strength
- low libido, ED
- shrinking testicles
- visual disturbances
hypogonadatrophic hypogonadism
if hypogonadism suspected, first obtain what labs
- LH
- FSH
- free and total testosterone
- will tell if primary or secondary
If secondary hypogonadism, the get what tests
- prolactin, TSH, CBC< CMP
- MRI pituitary
Before treating patient with hypogonadatrophic hypogonadism, make sure what
- DRE and PSA are within normal limits
most common tx of hypogonadatrophic hypogonadism
- androgens intramuscular 200 mg q 2 weeks
patients on tx for hypogonadatrophic hypogonadism needs to have what checked
- CBC q monthly for the first 6 months (risk of erythrocytosis)
- free estradiol q 2 months for first 6 months
- PSA and DRE annually
define panhypopituitarism
- deficient secretion of majority of pituitary hormones
- TSH, ACTH, GH, FSH, LH, prolactin
What is central diabetes insipidus
- insufficient ADH production
- serum osmolarity is preserved as normal
- urine is dilute
- urine osmolarity < 300 mOsm/kg
ADH levels in central vs nephrogenic DI
- central: ADH is low
- nephrogenic: ADH high
clinical presentation
- dilute urine and polyuria
- dehydration
- intense thirst
diabetes insipidus
diagnostic work up of Diabetes insipidus (nephrogenic or central)
- 24 hr urine
- serum electrolytes and glucose
- urine osmolarity
- urine specific gravity
-
water deprivation and vasopressin challenge
- in central will see > 100% increase in urine osmolarity with challenge
- in nephrogenic will see no elevation in urine osmolarity
tx of central DI
desmopressin (DDAVP)
tx of nephrogenic DI
- indomethacin with
- HCTZ
- DDAVP
What is SIADH and how does it present
- excessive production of ADH
- concentrated urine
- hyponatremia
