Pituitary Flashcards
(33 cards)
What does the intermediate lobe of the pituitary contain?
Endorphins
MSH
What are the hypothalamus releasing hormones?
TRH
GnRH
CRH
GHRH
What are the hypothalamus inhibiting hormones?
DA - dopamine/prolactin
Somatostatin: inhibits GH, TSH
How do you measure hormones w/ longer half lives (not bound) vs hormones bound to proteins?
Measure directly w/ random test (TSH)
Measure free & total fractions (total & free T4)
When are suppression tests used? What is an example?
When hyperfunction of gland is suspected
- high cortisol
- ex. dexamethasone
What are stimulation tests used for? What is an example?
Suspicious of hypofunction
- low cortisol
- ex. ACTH stimulation test
What disorders are seen in the hypothalamus? What are they associated w/?
Tumors
Inflammation
Infiltration
Metastatic tumor
*Associated w/ loss of posterior pituitary function
V1a receptors mediate…
pressor activity
V1b or V3 receptors modulate…
ACTH secretion
V2 receptors mediate…
renal handling of water excretion & promote coag factor VIII
What is the MOA of ADH?
Decrease water excretion in central diabetes insipidus & nocturnal eneuresis
Increase levels of factor VIII & improve platlets
What is the cause of central diabetes insipidus?
50% Idiopathic
CNS surgery, trauma, encephalopathy
Tumors
Metastasis
Granulomatous disease
Hereditary: autosomal dominant
Pregnancy
What are signs & sx of central diabetes insipidus?
Acute
Unremitting sustained thirst & polyuria day & night
Preference for cold liquids
Deficient secretion of ADH
Describe the test used for diabetes insipidus
Dehydration test:
Glucose, Ca, K, creatinine
Screen 24hr urine
Diagnosis = “water deprivation test”
No response to desmopressin injection w/ elevated ADH indicates…
Nephrogenic diabetes insipidus
What is seen w/ primary polydipsia?
Na & Osm mid range or low-normal at start
How do you distinguish primary polydipsia from CDI?
CDI: thirst improves w/ tx
PPD: thirst does NOT improve w/ tx
Tx of neurogenic DI (in general)
Aimed at decreasing urine output
Replacement of fluid losses
What med is used to treat CDI?
Desmopressin, potent anti-diuretic
What meds can you use to treat pts w/ CDI who are unresponsive to desmopressin?
Chlorpropamide
Carbamazepine or clofibrate
What is nephrogenic DI?
Resistance of the kidneys to the effects of ADH
No response to DDAVP
What are the 2 MC causes of nephrogenic DI?
Chronic lithium use
Hypercalcemia
What med & diet change is used to treat nephrogenic DI?
Thiazide
Low salt diet
Inappropriate ADH leads to…
volume expansion due to water retention
