Pituitary Pathophysiology (5/15) Flashcards
What can cause pituitary hypersecretion of a hormone?
Only pituitary adenomas
What can cause pituitary hyposecretion of a hormone?
- Any dis of pit or hypothalamus can cause deficiency of any hormone made by the ant pit
- Only a dis or hypothal or infundibulum can cause a def of vasopressin and thereby cause diabetes insipidus
What happens when you have a deficiency in GH?
- Short if prior to epiphyseal closure
- Dec muscle mass and inc fat
- Dec bone mineral density
What happens when you have a deficiency in prolactin?
Dec lactation
What happens when you have a deficiency in ACTH?
Hypocortisolism
What happens when you have a deficiency in TSH?
Hypothyroidism
What happens when you have a deficiency in LH/FSH?
Hypogonadism
How do we treat GH def?
Somatotropin (synthetic GH) which promotes bone growth in children and improves BMD in adults
What are the cells in the pit that produce peptide hormones? Whats special about them?
Somatroph, lactotroph and corticotroph
-Adenomas in these cells tend to produce physiologic effects
What are the cells in the pit that produce glycoprotein hormones? Whats special about them?
Gonadotroph, thyrotroph
-Do not cause physiologic effects so they are harder to recognize
What are the clinical syndromes associated with somatotroph adenomas?
- Gigantism (before epiphys closed)
- Acromegaly (after plate closure)
What are the features of acromegaly?
Facial: large nose, ears, lips with prominent jaw.
Hands: large with large fingers
What are the consequences of acromegaly?
- Osteoarthritis
- Colon cancer
- CVD
- Diabetes
- Neuropathy
- Sleep apnea
- Inc mortality
How do we diagnose acromegaly?
Chemical:
- Lack of suppression of GH to an oral glucose load
- Elevated serum IGF-1
Pathologic:
- Histologic appearance of pit adenoma
- Immunospecific staining for GH
How do we treat acromegaly?
- Surgically
- Pharma
- Radiation
What pharma treatments are there for acromegaly?
- Dopamine agonists (paradoxical effect, dopamine usually causes an inc in GH, here it suppresses it)
- Somatostatin analogs (inhibit GH release)
- GH receptor antag
How do we measure if treatments are working?
Adenoma size and IGF-1 levels
What is Pegvisomant?
GH receptor antagonist that binds to one part of GHR dimer with higher affinity than GH and prevents normal action of GH throughout the body. It reduces IGF-1 but has no effect on adenoma size, don’t act at level of pituitary (dopamine agonists and somatostatin analogs dec pit size)–>really the only one that wont dec size!
What is a lactotroph adenoma?
Tumor that makes tons of prolactin
What inhibits prolactin release?
dopamine
What can cause hyperprolactinemia
Many things, not just adenoma since DA inhibits its release…it could be a lack of DA, taking DA receptor antag, estrogens, opiates etc
Why does lactotroph cause hypogonadism
Prolactin inhibits secretion of gonadotropins
What are the clinical syndromes from lactotroph adenomas in premenopausal women?
- Amenorrhea or oligomenorrhea
- Galactorrhea
What are the clinical syndromes from lactotroph adenomas in post menopausal women
-Neurologic symptoms. The first way we discover lactotrph adenoma is usually because of hypogonadism. Post meno women have this already so it will progress and becomes so large that they get neurologic symptoms.
