Hypothalamic and Ant pituitary disorders Flashcards
What hypothalamic releasing hormone stimulates release of Prl?
TRH
What 3 factors act on the Anterior pituitary to regulate release of prl? #
TRH+
Dopamine -
Suckling +
Prl acts on two tissues. What are they and what are the actions? #
Breast: breast development, milk production
Hypothalamus: lnegative feedback, GnRH suppression
Somatostatin causes negative feedback for on the anterior pituitary downregulate release of what 2 hormones?
GH, TSH
Dopamine down regulates secretion of what 2 hormones from the anterior pituitary?
TSH, PRL
Name some hormones inhibited by somatostatin.
GH, ADH, thyrotropin(TSH)
What is the clinical syndrome that results from deficiency of GH?
Children: short stature
Adults: varies
What is the clinical syndrome that results from deficiency of FSH?
infertility
What is the clinical syndrome that results from deficiency of LH?
Men: hypogonadism, reduced sperm count
Women: hypogonadism, amenorrhea, oligomenorrhea
What is the clinical syndrome that results from deficiency of TSH?
hypothyroidism
What is the clinical syndrome that results from deficiency of ACTH?
Hypoadrenalism- loss of pigmentation
What is the clinical syndrome that results from deficiency of ADH?
diabetes insipidua
What is the clinical syndrome that results from deficiency of OT?
Failure of milk- let down, failure of uterine contraction, post-partum bleeding?
Why would you give both thyroxine and cortisol to someone who had anterior pituitary deficiency?
Thryoxine increased metabolism and that person can go into adrenal crisis due to the renal insufficiency. Always give cortisol with it.
T or F. Thyroxine is a potent pre-puberty growth stimulator.
T.
How could someone with Sheehan syndrome present? #
Panhypopituitarism- s/s of any or all deficiencies with the most life threatening being ACTH (GIVE CORTISOL), followed by TSH, then FSH/LH, and lastly GH.
What is the most common secretory pituitary tumor?
Prolactin
What is the effect of ant. pit. prolactinoma?
Females: amenorrhea, oligomenorrhea, galactorrhea, infertility, osteopenia,
Males: hypogonadism, decreased libido, galactorrhea, pit. deficiencies
#: Also impotence and gynocomastia in men. Bitemporal hemianopsia.
Cause of cushing’s disease
Excess cortisol. Glucocorticoid therapy, ACTH producing ptiuitary adenoma, adrenocortical tumros, ectopic ACTH production
Cause of acromegaly/gigantism?
GH excess
Clinical effects of hormonal excess of gonadotropins?
visual disturbances, headaches, hypogonadism
Four different things that can cause an elevated PRL
- Hypothalamic dopamine def
- Defective dopamine delivery
- Lactotroph insensitivity to dopamine
- Stimulation of lactotrophs. In primary hypothyroidism there is an increased TRH and TSH that could stimulate lactotrophs.
The serum prolactin concentration is much higher in pt with a _____.
macro-adenoma
What does bromocriptine do to LH and FSH activity in hyperprolactinemia?
Increase in frequency of LH and FSH pulses and an increased mean LH. These pt can become fertile.
What is responsible for negative feedback on the hypothalamus to reduce GHRH release?
IGH1, GH, aging, disease, hyperglycemia
What causes positive feedback on the hypothalamus to increase secretion of GHRH?
Sleep, stress, hypoglycemia
What causes negative feedback on the ant. pituitary to reduce secretion of GH?
SS, GH, IGF1
Is IGF1 pulsatile?
No. Carried by stable proteins and does NOT respond acutely to changes.
What will happen if you give a pt with acromegaly glucose?
Glucose will go up, but GH does not go down like it should
Etiology of acromegaly
Pituitary adenoma most commonly.
Define gigantism#
Excess linear height of 2SD above mean which can occur when excess GH acts on growth plates.
What may gigantism be associated with?#
McCune Albright syndrome, MEN1 (3Ps)
What should be included in DDx with gigantism?#
Precocius puberty, normal genetics, hyperthyroidism
Risk of long term GH#
hepatomegaly, cardiomyopathy, peripheral neuropathies, glucose intolerance and diabetes mellitus, headache due to mass effect and bitemporal hemianopsia
Describe onset of acromegaly and gigantism.#
Acro: insidious, 3rd decade of life
Gig: dramatic, more acute, younger
Is there an icnreased cancer risk in pt with excess GH?
Yes. Particularly colon and GI
Describe steps you would take in diagnosing a GH secreting pituitary adenoma.
- Look at IGF1 (high)
- OGTT with GH levels (inadequate suppression of GH)
- Pituitary MRI
- Mass or empty sells- GH secreting pituitary adenoma
- Normal: look at chest and abdominal CT to see if there is an extra-pituitary acromegaly
Is sweating a common complaint with people who have acromegaly?
Yes
Prognosis of Acromegaly#
Cardiac failure is most common cause of death. Increased risk of Colon cancer and pit. insufficiency
Other than pituitary adenoma, what types of tumors can secrete GHRH to increase GH secretion?
Islet cell tumor, carcinoid tumor int he lung
