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23 Cards in this Set
- Front
- Back
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Pituitary close to ...
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Internal carotids
CN III, IV, V1, V2, VI optic chiasm |
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anterior pituitary
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positive control from hypothalamus (except prolactin under negative tonic dopaminergic control)
ACTH, TSH, GH, LH, FSH, Prolactin |
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ACTH
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regulated by corticotropin releasing hormone (CRH)
stimulates cortisol release from adrenal glands cortisol has neg feedback excess cortisol leads to Cushing's syndrome, deficiency leads to adrenal insufficiency |
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TSH
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regulated by Thyrotropin Releasing Hormone (TRH)
stimulates thyroid hormone release from thyroid Thyroid hormone has negative feedback excess leads to central hyperthyroidism, deficiency leads to central hypothyroidism |
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FSH & LH
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Regulated by GnRH
stimulates testes and ovaries to ... males: testosterone secrete & spermatogenesis females: estradiol secrete & gametogenesis excess leads to precocious puberty, deficiency leds to hypogonadism |
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Prolactin
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under tonic inhibition by dopamine
targets the breast to lactate excess leads to galactorrhea and amenorrhea, deficiency leads to inability to lactate |
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Posterior Pituitary
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ADH, Oxytocin
synthesized in neurosecretory cells (supraoptic & paraventricular) |
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ADH
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regulated by plasma osmolality and blood volume
affects H2O permeability in collecting tubule excess leads to Syndrome of Inappropriate Secretion of ADH, deficiency leads to Diabetes Insipidus |
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Oxytocin
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Regulated by neurotransmitters (cholinergic & alpha adrenergic
causes milk let down from breasts and uterine contractions during labor |
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Cushing's Syndrome
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Result of chronic glucocorticoid excess
ACTH-dependent - Cushings disease, Ectopic ACTH, Ectopic CRH ACTH-independent: Adrenal adenoma, Adrenal carcinoma, micro/macronodular hyperplasia Pseudo: Depression, EtOH DX: centripetal obesity, buffalo hump, hyperpigmentation Confirm: Urine Free Cortisol >3x normal limit x2 catches, Dexamethasone suppression test, loss of diurnial variation TX: surgical resection w/ radiation, tumor removal, unilateral adrenalectomy |
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Dexamethasone Variation Test
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synthetic glucocorticoid given leading to ACTH suppression via neg feedback in healthy individuals, no suppression in Cushing's syndrome
10-20% false positive b/c obesity, depression, EtOH |
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Differentiating ACTH-independent from ACTH-dependent Cushings
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Plasma ACTH levels
<5 pg/ml --> adrenal cushings (independent) --> CT adrenals >10 pg/ml --> pituitary (ectopic) cushings (dependent) 5-10 pg/ml not definitive worry about ACTH secreting tumor w/ increased ACTH release |
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Differentiating pituitary v. ectopic ACTH dependent Cushings
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High Dose Dexamethasone suppression test: high dose dexamethasone should suppress serum ACTH in pituitary Cushings but serum ACTH should remain high with ectopic ACTH
Petrosal sinus sample (last resort invasive surgical procedure) MRI pituitary once positive results for pituitary Cushings. can't use to DX b/c 10-20% false positive |
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Acromegaly
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excess GH from pituitary tumor (99%) after epiphyseal plate closure (before --> gigantism)
presents: acral enlarge, facial changes, arthralgias, sweating, skin tags, greasy skin, HTN, DM, sleep apnea Increased incidence: arthropathy, neuropathy, CV dz, HTN, resp dz, colon ca, carb intolerance TX: transsphenoidal surg (50% effective), somatostatin analoges (preferred), radiation, DA agonists, GH antagonists |
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Diagnosis of Acromegaly
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Failure of GH to suppress Oral Glucose Tolerance Test (gold standard)
IGF-1 increased, 10-15% false neg due to lever dz, hyperglycemia, malnutrition |
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Prolactinomas
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most common secretory pit tumor
female: amenorrhea, infertility, galactorrhea men: decreased libido, impotence, galactorrhea, mass effects (headache & vision changes) DX: increased prolactin, abnormal pit MRI Exclude: hypothyroid, renal fail, cirrhosis, preg, stress, haloperidol, compression of pit stalk TX: DA agonists (Bromocriptine, Cabergoline), surgery and rad if medical fails |
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Thyrotrope Adenoma
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TSH secreting, rare
Hyperthyroidism Mass effects (headache, abnormal visual field) TX: surgery |
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Gonadotrope Adenoma
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FSH (most common), LH, or alpha subunit secreting
no obvious clinical syndrome Mass Effects Hypopituitarism from deficiency of other hormones TX: surgery |
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Diabetes Insipidus
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Insufficient ADH
polyuria, polydypsia, thirsty central - abrupt onset nephrogenic - slow onset Central: Congenital, iatrogenic, trauma, neoplasm, ischemia (sheehan), granuloma (sarcoid), infection, autoimmune Nephrogenic: Congenital (X-link), renal dz, electrolyte disorder, drugs (lithium, demeclocyclin) DX: polyuria, low urine specific gravity + osmolality central responds to ddAVP (vasopression analog) TX: ddAVP (central), NSAIDs & thiazids (nephrogenic) |
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hypopituitarism
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deficiency of one or multiple pit hormones
GH, FSH, LH most often TSH, ACTH, ADH last to diminish |
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Sheehan's Syndrome
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Ischemic pituitary necrosis following childbirth. associated w/ postpartum hemorrhage and HOTN
Failure to lactate |
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Pituitary Apoplexy
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Hemorrhagic infarct of pituitary adenoma.
presents w/ headache, mental status changes, opthalmoplegia, visual loss DX: MRI, endocrine test TX: surgical, hormone replace |
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Pituitary Incidentalomas
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10-20% MRIs pick up incidental adenomas.
exclude hormonal hypersecretion, hypopituitirism & visual change w/ macro follow up MRIs at 6 mo, 1,2,5 yrs |
