OnlineMedEd: Endocrine - "Anterior Pituitary" Flashcards
Why does the posterior pituitary not fit into the H-P-X axis?
The posterior pituitary is a continuation of the hypothalamus, so it does not require an intermediary hormone from the hypothalamus.
Review the anterior pituitary hormones from most-to-least necessary.
- ACTH
- TSH
- GH
- FSH/LH
List the hypothalamic hormones, their pituitary counterparts, their target organs, and the final hormone.
- CRH -> ACTH -> adrenal glands -> cortisol
- TRH -> TSH -> thyroid gland -> T4
- GHRH -> GH -> liver -> IGF1
- GRH -> FHS/LH -> gonads -> testosterone/estrogen
Describe the presentations of prolactinomas in men and women.
- Women: secondary amenorrhea, galactorrhea; microadenomas because caught early
- Men: decreased libido, bitemporal hemianopsia; macroadenomas caught late
How should you work up suspected prolactinoma?
- First, review medications for dopamine antagonists
- Second, check a TSH and prolactin level. (Dustyn says to do these as separate steps, but I think in real life you do both at once.)
- Third, do an MRI for tumor if prolactin levels high
True or false: prolactinomas are not usually treated surgically.
True
Cabergoline is the mainstay treatment. Bromocriptine can also be used but has a worse side effect profile.
____________-thyroidism can cause prolactinemia.
Hypo
TRH stimulates the release of prolactin. Hypothyroidism causes increased TRH release.
Describe the different presentations of acromegaly based on age.
- Kids: gigantism
* Adults: growth of hands, feet, face, visceral organs, and diabetes (because GH stimulates glucose production)
_____________ usually causes death in those with acromegaly.
Diastolic heart failure (because of heart growth)
To work up acromegaly, start with ___________.
IGF-1 levels
If this is elevated, do a glucose suppression test.
If the glucose suppression is also positive, then do an MRI.
List the two treatments for acromegaly.
- Surgery
* Octreotide
What vital sign abnormalities will you see in hypocortisolism?
- Hypotension
* Tachycardia
The three groups of causes of acute hypopituitarism are _______________.
infection, infarction, and iatrogenic
Apoplexy is usually caused by ____________.
a tumor that causes an infarction
In cases of chronic hypopituitarism, the body diverts pituitary resources to _____________.
ACTH and TSH (at the expense of GH, FSH, and LH)