Pituitary Pathophysiology Flashcards
4 categories of disease of the hypothalamus and pituitary?
Tumors
Infiltrative diseases
Meningitis
Trauma
3 broad types of tumors that affect the hypothalamus and pituitary?
Adenomas of the ant. pituitary.
Tumors from embryological remnants (eg. Rathke’s cleft cells).
Metastases to the hypothalamus.
3 infiltrative diseases that can affect the hypothalamus and/or pituitary? Where does each affect?
Hemochromatosis - pituitary.
Sarcoidosis - hypothalamus.
Langerhans cell histiocytosis - hypothalamus.
What’s the only kind of pituitary disease that can cause hypersecretion?
Pituitary Adenoma
In contrast… pretty much any problem can cause hyposecretion.
3 effects of GH deficiency? (there may be more)
Shortened stature (if occurs prior to epiphyseal closure).
Reduced muscle mass, increased fat mass.
Decreased bone mineral density.
What’s the one pituitary hormone we can’t currently replace?
Prolactin
How does hormone structure relate to the presentation of pituitary adenomas?
“-trophs” that make peptides are more likely to present with signs of hormone imbalance. (GH, PRL, ACTH)
“-trophs” that make glycoproteins are less likely to produce functional hormones, and thus more often don’t present until tumor is causing a mass effect. (FSH, LH, TSH)
(obviously this is not 100%)
2 clinical syndromes caused by somatotroph adenomas? What determines the difference between the two?
Gigantism and acromegaly.
Gigantism occurs when GH levels are high before the closure of epiphyseal plates.
What does somebody with acromegaly look like?
Enlarged facial features - supraorbital ridge, jaw, nose etc.
Bigger feet, bigger fingers.
Two lab tests for a GH-secreting somatotroph adenoma?
See if GH/IGF-1 is suppressed in response to glucose load - won’t be suppressed if adenoma.
Measure IGF-1 - will be elevated if adenoma.
6 bad to life-threatening consequences of acromegaly?
Severe osteoarthritis.
Cancer, esp of the colon.
CV disease.
Diabetes mellitus.
Neuropathy - esp. things like carpal tunnel syndrome.
Sleep apnea (due to thickened pharyngeal tissues).
3 types of Tx for somatotroph adenoma?
Surgery.
Medications.
Radiation.
3 pharmacologic treatment of somatotroph adenoma?
Dopamine agonists (paradoxical effect).
Somatostatin analogues.
GH receptor antagonists.
What’s the deal with using dopamine agonists for somatotroph adenoma?
Dopamine leads to GH release in normal somatotropes.
But in somatotroph adenomas, dopamine suppresses GH release.
What’s the name of the dopamine agonist mentioned as being used for acromegaly (and for hyperprolactinema)?
Cabergoline. (ergot derivative. Ergotism -> delirium / psychosis due to dopamine activity…)
What’s one GH receptor antagonist?
Pegvisomant (binds to dimerized GH receptor)
Difference in lactotroph adenoma presentation in pre-menopausal vs. post-menopausal women? Why?
Pre-menopausal: amenorrhea / oligomenorrhea, galactorrhea.
Post-menopausal: mass effect neuro symptoms.
Post-menopausal women don’t have periods to mess up and apparently breast tissue isn’t responsive to PRL, and thus tumors present later.
Effects of lactotroph adenoma in men?
Decreased libido, fertility, potency.
4 normal causes of PRL release?
Pregnancy
Nursing
Exercise (?)
Stress (physical and psychological)
Are lactotroph adenomas the only cause of hyperprolactinemia? One way to distinguish?
Nope, can be caused by lots of things, esp. dopamine antagonists, estrogens, opiates, etc.
PRL levels from lactotroph adenomas will typically be much greater than from other causes.
2 clinical syndromes associated with corticotroph adenomas?
Neuro effects from mass effect.
Cushing’s syndrome.
What’s a pharmacological treatment for thyrotroph adenoma?
Somatostatin analogues.
Most common presentation of gonadotroph adenoma?
Neuro signs and symptoms due to mass effect.
2 hormonal syndromes that can be caused by gonadotroph adenoma?
Precocious puberty in males due to LH.
Ovarian hyperstimulation in pre-menopausal women due to high FSH.
