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52 Cards in this Set
- Front
- Back
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anatomy surroundeing the pituitary
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tumors lateral: cavernous sinus and may hit CN 3, 4, V1, V2, & 6
tumors superiod: hit optic chiasm |
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pituitary hormones from anterior lobe
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GH
prolactin ACTH TSH FSH LH |
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pituitary hormones from posterior lobe
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ADH
oxytociin |
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regulation of anterior pit hormone secretion
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3 tiers of control
hypothalmic hormones traverse the portal system and impinge directly upon their respectivetarget cells intrapituitary cytokinesand GF's regulatetropic cell function by paracrine & autocriine control peripheral hormones exert negative feedback inhibition of respectivepit trophic hormone syn and secretion |
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hypothalmic pituitary disorders
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hypothalmic disease
stalk interruption pituitary tumors: mass effects iatrogenic: surgery, radiation, steroids invasive: other CNS, tumors, metastases infarction: sheehan's diabetes apoplexy: hemorrhage infiltrative: hemochromatosis trauma immunologic: lymphocytic hypophysitis genetic: Pit-1, prop-1 mutations isolated ACTH non-pituitary |
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hypothalmic disease
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mass
infiltrative: sarcoidosis, langerhans histiocytosis functional: steroids, illness, wt loss |
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non pituitary
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cranioipharyngioma
rathke's cleft cyst meningioma carotid artery aneurysm |
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evalutation of hypothalmic-pituitary disorders
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size/mass effect
- headache, nausea, vomiting - visual disturbance: bitemporal hemianopsia function: hypo or hyper |
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piuitary tumor subtypes
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mostly lactotroph 40-50%: hyperprolactinemia
gonadotroph 15-40% : clinically non functioning; visual field loss & hypopituitarism somatotroph 10-20% : acromegaly corticotroph 10-15% : cushings disease thyrotroph 1% : hyperthyroidism |
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prolactin actions
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stimulates milk production from mammary gland
importnat for normal reproductive development |
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hyperprolactinemia
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most common pituitary abnormality
frequent cause (25-40%) of female infertility |
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prolactin secretion
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TRH and prolactin releaseing factor stimulate releasefrom anteerior lobe
- breast - decrease LH, FSH -- decrease gonadal function/gonads - other: lymphocytes, brain, tear ducts, nephron, gut, liver decrease GnRH pulses causses dopamine release which inhibits prolactin secretion |
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how does hyperprolactinemia present in women
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galactorrhea
amenorrhea or oliomenorrhea (by decrease GnRH pulses) infertility |
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how does hyperprolactinemia present in men
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more likely to present with headache, tumor
impotence, infertility not galactorrhea or gynecomastia tumors b/c suddle symptoms ignored |
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physiologic causes of hyperprolactinemia
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stress: hypoglycemia, exercise, injury
sexual intercourse estrogen: women>men; pregnancy; obesity protein meal nipple stimulation |
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pathologic causes of hyperprolactinemia
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meds
untreated primary hypothyroidism: increase TRH polycystic ovarian syndrome RF stalk compression or section: neurosurgery, empty sella, non pit CNA tumors chest wall lesions: herpes zoster, chest contusion, mastitis pituitary tumor |
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meds that cause pathologic hyperprolactinemia
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antipsychotics
antidepressants birth control pills estrogen pills |
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pituitary tumor
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prolactinoma
GH secreting ACTH secreting nonsecretory: large |
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prolactinomas
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microadenoma: < 1 cm
- stable over time macroadenoma: > 1 cm - increase over time - requires specific therapy size & PRL concentration should decrease with therapy |
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specific therapy for macroadenoma (prolactinoma)
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dopamine agonist
- bromocriptine : requires daily dosage - cabergoline: fewer side effects, possibly more otent; can dose weekly - surgery, radiation, or all of the above |
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indications for dopamine agonist therapy
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infertility
amenorrhea: bone loss or osteoporosis bothersome galactorrhea decrease size of tumor: macroadenoma |
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hyperprolactinemia summary
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common
- excluse hypothyroidism, meds, pregnancy prolactin secreting tumors - microademonas can be watched or treated and followed - macro need tx: D aaonist, surgery and/or radiation therapy |
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GH axis
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ghrelin (from stomach) & GHRH stimulate GH secretion
somatostatin from pancreas inhibi GH release GH goes to liver and releases IGF-1 which goesto bone & muscle GH also works directly at bone & muscle IGF-1 is end organ functional GH; it is steady and this is what we measure |
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acromegaly
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changing hands, feet (wider), head (lantern jaw), leonine facies, increase frontal sinuses, widened teeth
arthralgias visual field disturbance soft tissues grow: thyroid, heart, liver, etc |
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acromegaly presentation
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hyperhidrosis
headache hormone def macroglossia sleep apnea |
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dx of acromegaly
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measurement of random GH not useful
- NI at times in acromegaly - high following a normal pulse IGF-1: somatomedin C - integrated measure of GH levels - high in acromegaly: best screening test oral glucosetolerance test - normal suppress GH to < 1 - acromegalics do not suppress head MRI scan |
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if you think there is hormone overproduction, what test do you do
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suppression test
also can measure when should be low, to demonstrate overproduction |
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if you think hormone levels are too low, what do you do
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measure when should be high
measure cortisol in am |
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secretion of GH in normal adult
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pulsatile
mostly at night |
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GH secreting tumors summary
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gigantism or acromegaly: based on timing
dx: increase IGF 1 and abnormal GH response to OGTT dx late: largetumorwith multiple hormone def tx may require surgery +/- radiation +/- GH antagonist |
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ACTH cortisol axis
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CRH stimulates ACTH which goes to medulla and releases epi & NE; also goes to cortex and releases aldosterone, androgens, cortisol
end hormones negative feedback to hypothalamus & pituitary |
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cushing syndrome : clinical S/S
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centripetal obesity: buffalo hump, moon facies
DM, HTN mood affect easy bruising purple striae proximal muscle weakness hypokalemia androgens: acne, hisrutism, menstraul irregularities |
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dx of cushing sndrome
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high cortisol
- 24 UFC (urinary free cortisol) - midnight salivary cortisols (should be low at this time) - 1 mg dexamethasone suppression test (cortisol should go to 0 if normal) after cushing confirmed, ACTH to determine level of problem |
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cushing's syndrome
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exogenous: most common
endogenous - ACTH dependent: pituitary or ectopic - ACTH independent: adrenal |
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cushing syndrome tx
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surgey
medical with inhiitors of steroidogenesis - ketoconazole all will have adrenal insufficiency as result of tx |
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hypopituitarism
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gonadotropin: hypoonadism, infertility
ACTH: fatigue, ab pain, weakness (low cortisol) TSH: secondary hypothyroidism prolactin: failure of lactation postpartum GH kids: short stature, adults, fatigue, weakness, LGM, increased fat mass |
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dx of hypopituitarism
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TSH: low FT4, normal TSH
- beward of normal TSH asonly screen ACTH: low cortisol & ACTH - ACTH stim test, insulin tolerance test if not contraindicated LH FSH: low testosteron,e LH, FSH, estradiol - hypogonadotropic hypogonadism E2 not needed if menses normal GH: IGF-1 suggestive if low - GH reserve testing ITT prolactin: no reserve testin necessary AVP : AM urine for osmolality, serum Na, further evaluation if symptoms of DI - unmasking of DI with cortisol replacement |
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multiple hormone failure
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think hypopituitarism
def of 1 or more pt hormones: anterior more than posterior causs: tumor, iatrogenic (surgery), trauma, autoimmune hypophysitis, infarction if one hormone def, look for others check hormones b4 surgery or anticipated stress |
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post pit
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arginine vasopressin = AVP = ADH
disorders: - DI: too little action - SIADH: too much action (blood like water) |
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AVP action
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V2R on collecting tubue of kidney
- insertion of AQP2 water channel into apicalmembrane of CD epithelial cell - passivewater reabsorption - along osmotic gradient V1aR on vascular smooth muscle cell - AVP mediated vasoconstriction V1bR on ant pit corticotrophs -regulation of ACTH secretion |
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Stimulus for AVP release
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increase pOsm: 280-285
- small increase in pOsm : 1-2% really increases AVP - max conc urine when AVP is 5 pg/ml - pOsm 290-295 - >10 mOsm above osmotic threshold decrease p Vol decrease BP: via Baroreceptors in carotid A's and aortic arch; relatively weak stimuli nausea, vomiting, pain meds, AI I, opiods |
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back up mechanism for water absorption
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thirst
increase p Osm at 295 (higher than AvP) via osmoreceptors in hypothalamus and wall of 3rd ventricle |
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DI
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polyuria without osmotic stimuli
24 hr urine volume > 50 ml/kg spec gravity < 1.010 Uosm < 300 |
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DI presentation
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no free water reabsorption
polyuria polydipsia 5-10 L / day |
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DI dx
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symptoms : polyuria, polydipsia, volume depletion
increasae serum Na with copious dilute urine confirm with water deprivation test |
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DI causes
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neurogenic: decrease AVP secretion: trauma, idiopathic
nephrogenic: decrease AVP action despite increase in concentration - genetic, sickle cell anemia, lithium therapy |
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DI tx
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free water intake by pt (drnk to thirst) or free water admin by provider, monitor serum Na
neurogenic: replace AVP - temporary: aqueous AVP by SQ injection -long term: long acting AVP analog: DDAVP (nasal spray or oral) once or twice daily nephrogenic: AVP admin won't work - hydrochlorothiazide: increases absorption of water in proximal tubule independent of aVP - treat underlying cause: stop lithium |
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SIADH
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ADH secreted in absence of hyperosmolar or hypovolemic (hypotensive) stimuli
CNS/hypothalmic: trauma, degenerative, vascular neoplastic drugs: stimulate ADH secreion neurogenic: pain, nausea benign/malignant pulmonary disease - pneumonia, emphysema, small cell |
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drugs that can induce SIADH
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chlorpropamide
carbamazepine vincristine vinblastin cyclophosphamide phenothiazines tricyclics SSRI |
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SIADH clinical
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S/S of hyponatremia
depends on acuteness lethargy, malaise nausea, vomiting confusion, mental status changes seizures low serum osm, concentrated urine natriuresis due to expansion of ECF - increase in GFR, ANP, suppression of RAA axis no edema |
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SIADH dx
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hypoosmolar hyponatremia, euvolemic
ADH excess is appropriate in CHF, ascites, nephrosis, hypovolemia, hypercortisolism, hpocortisolism low serum osm concentrated urine U Na > 20 mEq/L excluse hypothyroidism, adrenal insufficiency, & diuretics - must perform thyroid tests & ACTH stimulation test |
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SIADH tx
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fluid restriction
treat underlying problem AVP R inhibitor: conivaptan, tolvaptan ; if hyponatremia not responding to fluid restriction |
