PITUITARY Flashcards
What hormones are released from the anterior pituitary?
Growth hormone, prolactin, ACTH, TSH, LH, FSH
What hormones are released from the posterior pituitary?
arginine Vasopressin (ADH & AVP), oxytocin
What does the hypothalamus do?
Releases regulatory hormones, most of which stimulate the release of pituitary hormones
What does dopamine do to prolactin?
dopamine inhibits prolactin release
What is hypopituitarism and what causes it?
Hormone deficiencies – genetic defects, tumors, autoimmune, stroke, trauma/shock
What happens to LH/FSH in hypopituitarism?
Decreased sex hormones
Adolescence = delayed puberty
Adult = loss of secondary sex characteristics, decreased libido, amenorrhea, infertility, and low testosterone/estrogen
What labs might you see with low FSH.LH?
Low testosterone & estradiol
If hypopituitarism is congenital, what does it cause?
Hypogonadism
What happens to TSH hypopituitarism?
decreased thyroid hormone and thus HYPOthyroidism
What are the sxs of hypothyroidism?
Weakness, cold intolerance, constipation, skin/hair changes, weight gain, dyslipidemia
What labs might you see in TSH deficiency due to hypopituitarism?
Low TSH, Low FT4
What happens to ACTH in hypopituitarism?
Decreased cortisol and thus adrenal insufficiency
What are the sxs of adrenal insufficiency?
Weakness, fatigue, weight loss, hypotension
What labs might you see with ACTH deficiency?
Decreased cortisol, hyponatremia, and hypoglycemia
What happens to growth hormones in hypopituitarism?
Adults - Obesity, asthenia, decreased cardiac output
Children – serous growth disturbance
What is it known as when all of the anterior pituitary hormones are lacking?
Panhypopituitarism
What is the diagnostic study of choice to R/O any neoplasms of the pituitary or other CNS pathology?
MRI
: If there is a tumor on the pituitary gland, how do you treat it?
Transphenoidal pituitary surgery – followed by endocrine replacement therapy (L-thyroxin, testosterone or estrogen, cortisol, hGH
What are the 4 forms of diabetes insipidus?
Central, primary, secondary, and nephrogenic
What causes central diabetes insipidus?
Deficiency of AVP/ADH
What causes primary diabetes insipidus?
Often autoimmune; familial/genetic
What causes Secondary diabetes insipidus?
Damage to pituitary or pituitary stalk via tumor, surgery, or anoxia
What causes Nephrogenic diabetes insipidus?
Inability of kidneys to respond to ADH; lack ADH receptors; acquired (pyelo, post-obstructive, tubular interstitial); drug induce; hypercalcemia
How does someone present with diabetes insipidus & what would you see on labs?
INTENSE thirst, polyuria
Labs: serum-hypernatremia, urine – low specific gravity
If a patient has polyuria and polydipsia, what other diagnosis might you be thinking of?
DM & psychogenic polydipsia
How do you confirm diagnosis of DI? How does it work?
Vasopressin challenge – desmopressin will result in a dramatic decrease in urine volume
**Use only for central DI!
How do you treat central DI?
Partial = none other than fluids
Complete = Desmopressin (use lowest effective dose to avoid hyponatremia!)
How do you treat nephrogenic DI?
Indomethacin
If a patient presents with enlargement of hands, jaw, and feet what is this known as?
Acromegaly
What is acromegaly?
When excessive growth hormone is released
What causes acromegaly?
Almost always from a pituitary adenoma
What does the pituitary adenoma often produce along with excessive GH?
Prolactin
How would the patient present if prolactin & GH are being secreted?
Hypogonadism
What is specific about the adenoma of gigantism?
Develops BEFORE closure of epiphyses
What is specific about the adenoma of acromegaly?
Develops AFTER closure of epiphyses
What are some associated findings of acromegaly?
Hypertension, dilated cardiomyopathy, insulin resistance/diabetes
Why is it that diabetes occurs with acromegaly?
GH counteracts the actions of insulin
IF there is lots of GH being released, what would we see a lot of in the body?
IGF-I in the liver
How elevated would the IGF-I be in acromegaly?
5x normal
IF we see low TSH/FT4 along with high amounts of IGF-I, what does that mean?
Suggests additional pituitary pathology
What diagnostic study must we do to confirm acromegaly?
MRI
How do you treat Acromegaly?
Transphenoidal microsurgery
Give octreotide – suppresses GH if it continues to secrete post-op
What does prolactin do?
Induces lactation during pregnancy
What controls prolactin?
Always being inhibited by dopamine
If a pre-menopausal woman has galactorrhea and oligo/amenorrhea, what should you consider to be a cause?
Hyperprolactinemia
What causes hyperprolactinemia?
Pituitary microadenoma, drugs (SSRI’s & thiazides), hypothyroidism, renal failure, and cirrhosis
Why would a patient have oligo/amenorrhea with hyperprolactinemia?
Because the excess prolactin suppress GnRH thus, decreasing LH/FSH
How would a male present with hyperprolactinemia?
Decreased libido, erectile dysfunction, and gynecomastia
What would the prolactin level be to be highly suspicious of a prolactinoma?
> 250
How do you treat hyperprolactinemia?
D/C offending drug, microprolactinolmas grow very slowly and patients can be followed without intervention
If large = dopamine agonists then do transphenoidal surgery
