Small Group Flashcards
what suppresses prolactin release in the anterior pituitary, and where does it come from?
dopamine produced in the arcuate nucleus of the hypothalamus
what does prolactin inhibit?
synthesis & release of GnRH
what key symptoms suggest excessive prolactin secretion?
amenorrhea & galactorrhea
If a patient had high prolactin levels and amenhorrhea, what would you expect to see if you gave them GnRH?
GnRH would increase the secretion of LH and FSH if the gonadotropes were unaffected by a tumor
What does Sudan III staining look for?
presence of fat in breast discharge
which is a common cause of hyperprolactinemia?
pituitary tumor
what is sheehan’s syndrome? what are the key symptoms?
postpartum hemorrhage results in ischemic pituitary
1) cannot lactate
2) amenorrhea (cycle doesn’t come back)
during sheehan’s syndrome, which hormone are compromised?
ACTH, TSH, LH, FSH, GH, prolactin
what are some hormone pairs that are affected by Sheehan’s?
ACTH- cortisol
GnRH- LH/FSH
TSH- T3/T4
what are the two categories of growth hormone excess?
acromegaly & gigantism
what are the tell-tale signs of acromegaly?
- change in facial appearance (mandible)
- increased shoe size
If GH is elevated, what other peptide is likely elevated? where is it produced?
IGF-1; produced in liver
what are the effects of excess GH? excess IGF-1?
GH: muscle cell proliferation (large tongue)
IGF-1 : chondrocytes/osteocytes/connective tissue proliferation, widening of digits, thickening of skull bones/mandible/ribs
both: proliferation of cells in liver/kidney/organs
in acromegaly, which is the tingling and joint pain caused by?
compression of nerves against bones in joints; increased cartilage
what inhibits GH?
hyperglycemia; somatostatin
You’d expect fasting insulin to be high/low in a patient with acromegaly?
HIGH- GH inhibits insulin-stimulated glucose uptake, high circulating glucose, no negative feedback on insulin
what inhibits GH? under what conditions is GH not secreted?
somatostatin; hyperglycemia
what is the signature of Cushing’s syndrome? what are some symptoms?
excess cortisol
1) weakness- cort breaking down muscle
2) bruising- loss of subcu fat
3) purple striae - central obesity, fragile skin
4) increase in plasma glucose (role of glucocorticoids)
how could you tell if a tumor was a pituitary adenoma (2), adrenal adenoma (1), iatrogenic (exogenous) or ectopic?
1) adrenal- low ACTH, confirm with CT
2) pituitary- dexamethasone able to block high ACTH, use MRI
3) iatrogenic- ask about pharma, see atrophy of zona fasiculata
4) extopic- high ACTH, not responsive to dexamethasone
what is the signature of Addison’s? what are some symptoms?
- no cortisol
1) light headedness, low blood pressure- hypotension from lack of aldosterone
2) high Ne/Epi ratio, high heart rate and low systolic pressure
3) pigmentation
4) electrolyte imbalance
what causes the skin pigmentation with Addisons?
ACTH transcribed with MSH (in POMC gene), high MSH results in hyperpigmentation
how can you tell the difference between primary and secondary/tertiary addisons?
primary- ACTH is high, cortisol doesn’t respond to exogenous ACTH
secondary/tertiary- ACTH is low, cortisol response to exogenous ACTH
what tests do you do for hypothyroidism? what would you expect to see?
measure TSH/free T4
- expect high TSH because T3 is probs low, lack negative feedback
how is T4 transported in blood?
75% bound to TBG
20% bound to TTR
5% bound to albumin
