Flashcards in Chapter 20: Pituitary Deck (35):
Releases TRH, CRH, GnRH, GHRH, and dopamine into median eminence; passes through neurohypophysis on way to adenohypophysis
Inhibits prolactin secretion
Supraoptic nuclei, regulated by osmolar receptors in hypothalamus
Paraventricular nuclei in hypothalamus
Does not contain cell bodies
80% of pituitary gland
Anterior pituitary (adenohypophysis)
What does the anterior pituitary release?
ADH, TSH, GH, LH, FSH, PROLACTIN
Blood supply of anterior pituitary
Does not have its own direct blood supply; passes through neurohypophysis 1st (portal venous system)
Pituitary mass compressing optic nerve (CNII) at chiasm
Almost always macro adenomas; present with mass effect and decreased ACTH, TSH, GH, LH, FSH. Tx: transsphenoidal resection
Tx: nonfunctional pituitary tumors
Contraindications to transsphenoidal approaches
Suprasellar extension, massive lateral extension, dumbbell-shaped tumor
Most pituitary tumors respond to...
Bromocriptine (dopamine agonist)
- MC pituitary adenoma
- Mostly microadenomas
- Most patients do not need surgery
When do symptoms occur with prolactinoma?
Prolactin is usually > 150 for symptoms to occur
Galactorrhea, irregular menses, decreased libido, infertility
Bromocriptine (safe in pregnancy) or cabergoline (both are dopamine agonists) for most or transsphenoidal resection for failure of medical management
When do you resect macroadenomas in prolactinoma?
Resection with hemorrhage, visual loss, wants pregnancy, CSF leak
HTN, DM, gigantism; can be life-threatening secondary to cardiac symptoms (valve dysfunction, cardiomyopathy)
- Usually macroadenomas
Acromegaly (growth hormone)
Elevated IGF-1 (best test), growth hormone > 10 in 90%
Octreotide or transphenoidal resection; XRT and bromocriptine can be used as secondary therapies
- Post partum trouble lactating (usually 1st sign)
- Can also have amenorrhea, adrenal insufficiency, and hypothyroidism
What causes Sheehan's syndrome?
Due to pituitary ischemia following hemorrhage and hypotensive episode during childbirth
Tx: Sheehan's syndrome
Benign calcified cyst, remnants of Rathke's pouch; grows along pituitary stalk to suprasellar location
Most frequently presents with endocrine abnormalities, visual disturbances, headache, hypocephalus
Surgery to resect cyst
Frequent complication s/p craniopharyngioma
What to look for in bilateral pituitary masses?
Check pituitary axis hormones; if OK, probably metastases
- Occurs after bilateral adrenalectomy resulting in amenorrhea and visual problems (bi temporal hemianopia)
Why amenorrhea and visual problems in Nelson's syndrome?
Bilateral adrenalectomy -> increased CRH causes pituitary enlargement resulting in amenorrhea and visual problems (bitemporal hemianopia)
Why hyperpgimentation in Nelson's syndrome?
Bilateral adrenelecotmy -> beta-MSH, a peptide byproduct of ACTH