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121 Cards in this Set

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DISORDERS OF THE PITUITARY - WILSON - MONDAY JAN 29
what is the most common abnormality of the anterior lobe?
pituitary adenoma
PITUITARY ADENOMAS
what % are secretory?
75%
how are they characterized, based on size (2)?
1) microadenomas (<1cm); 2) macroadenoma (>1cm)
what may symptoms be due to (2)?
1) hormonal secretion; 2) mass effects; or both
what are the most significant forms of secretory pituitary adenomas (3) in order of frequency?
1) prolactinomas; 2) GH-secreting adenomas; 3) ACTH-secreting adenomas
what are two less frequent forms of secretory pituitary adenomas?
1) LH/FSH secreting adenomas; 2) TSH-secreting adenomas
MASS EFFECTS OF PITUITARY ADENOMAS
what sense is impaired, why, and what example effect is seen?
impaired vision including field defects, such as bitemporal hemianopsia, due to compression of the optic chiasm or optic nerves, or both
movement of what muscles can be impaired, and why?
extraocular muscles - ocular palsies - due to compression of cranial nerves 3, 4, and 6, which control eye movement
what happens to the pituitary fossa (sella turcica)?
expansion and gradual destruction
what happens to intracranial pressure, and what is the result?
it increases, resulting in nausea and vomiting
what happens to the size of the pituitary gland, and why?
hypopituitarism, due to pressure-related destruction of surrounding normal cells of anterior lobe
what is the stalk effect, and what can cause it?
stalk effect is elevation of serum prolactin due to interference with normal inhibition of prolactin seccretion - this can be the result of any suprasellar mass
what is normal inhibition of prolactin secretion the result of?
transport of dopamine from the hypothalamus to the anterior lobe
what is pituitary apoplexy, and what can cause it (2)?
sudden enlargement of a pituitary macroadenoma due to hemorrhage or infarction
how seriuos is this condition?
surgical emergency
what are some of the severest effects of pituitary apoplexy (6)?
1) sudden severe headache; 2) diplopia; 3) hypopituitarism; 4) cardiovascular collapse; 5) loss of consciousness; 6) sudden death
PROLACTINOMAS
what adjectives were used to describe the way prolactin is secreted by these tumors (2) and what does each mean?
they secrete prolactin efficiently (microadenomas are symptomatic) and proportionally (serum levels correllate with size of tumor)
what group experiences the most signs and symptoms from prolactinomas?
premenopausal women
what are the signs and symptoms seen in premenopausal women (3)?
1) galactorrhea; 2) amenorrhea; 3) infertility
what are the effects like in postmenopausal women and and men?
hormonal effects are more subtle, and mass effects are more likely
what other type of tumor may result in elevated prolactin, and why?
elevated serum prolactin may accompany a non-proalctin-secreting macroadenoma due to stalk effect (a mass effect)
what are the treatments for prolactinomas (2)?
1) bromocriptine (dopamine agonist); 2) transsphenoidal resection
what does bromocriptine do to a prolactinoma?
shrinks tumor (controls, but not curative)
GH-SECRETING ADENOMAS (SOMATOTROPH ADENOMAS)
what do GH-secreting adenomas occasionally secrete, in addition to GH?
prolactin
what does GH hypersecretion stimulate to be secreted, and from where?
stimulates IGF-1 to be secreted hepatically (which causes many of the clinical effects)
what are the signs and symptoms called in postpubertal individuals?
acromegaly
what parts of the body does excessive growth most conspicuously involve (3)?
1) skin/soft tissues; 2) certain bones; 3) certain organs
what bones were mentioned (3)?
hands, feet, face - non-longitudinal bone growth
what organs were mentioned (4)?
liver, adrenals, heart, thyroid
what type of cancer is there an increased risk for in acromegaly?
GI carcinomas
what are other metabolic and physiologic abnormalities caused by acromegaly (6)?
1) diabetes mellitus; 2) HT; 3) CHF; 4) muscle weakness; 5) arthritis; 6) gonadal dysfunction
what are the signs/symptoms called in prepubertal individuals?
gigantism
what is gigantism characterized by, and what is disproportionately long?
excessive growth with disproportionately long extremities
how do the metabolic and physiologic abnormalities compare to acromegaly?
similar
what is a sensitive test for GH-secreting adenoma?
nonsuppression of GH production by oral load of glucose
what is the treatment for GH-secreting adenomas (3)?
1) transsphenoidal resection; 2) radiation; 3) drug therapy
what are the results of effective control of GH oversecretion (2)?
1) gradual recession of tissue overgrowth; 2) improvement of metabolic and physiologic abnormalities
ACTH-SECRETING ADENOMAS (CORTICOTROPH ADENOMAS)
what size are the majority of microadenomas?
microadenomas - can be as small as 2mm
what are the signs/symptoms of ACTH-secreting tumors called?
Cushing's disease
what do they directly result from?
hypercortisolism secondary to ACTH-secreting pituitary adenoma
what are the two groups of features of Cushing's disease?
1) somatic features; 2) metabolic and physiologic abnormalities
what are the somatic features (5)?
1) Moon facies; 2) central obesity (truncal obesity); 3) skin fragility (striae, easy bruisability); 4) poor wound healing; 5) osteoporosis
what are the metabolic and physiologic abnormalities (2)?
1) diabetes mellitus; 2) hypertension
what factors make it difficult to diagnose ACTH-secreting pituitary adenomas (3)?
1) possible alternative sources of ACTH hypersecretion (bronchial carcinoid, other tumors); 2) small pituitary microadenomas may be below threshold of detectability by imaging; 3) invasive diagnostic technique
what is the invasive diagnostic technique, and what does it involve?
bilateral catheterization of inferior petrosal sinuses - venous drainage of pituitary gland is lateralized to right and left petrosal sinuses, respectively
what type of assessment is done (what three things are measured to be assessed)?
1) right pituitary venous effluent; 2) left pituitary venous effluent; 3) peripheral blood
what is the treatment for ACTH-secreting adenomas?
transsphenoidal resection
LESS FREQUENT ESCRETORY ADENOMAS
what is secretion like in LH/FSH secreting adenomas?
secrete hormones inefficiently and variably
what is the clinical syndrome?
usually no recognizable clinical syndrome
what are the rares of all adenomas?
TSH-secreting adenomas
NONSECRETORY ADENOMAS
what are the hormonal effects of nonsecretory adenomas?
hypopituitarism
what is this due to, and what % does it occur in?
pressure-related destruction of surrounding normal cells of anterior lobe (75%)
INFARCTION
what lobe of the pituitary is particularly vulnerable to infarction?
the anterior lobe
why is it vulnerable?
because its main arterial blood supply, the portal vessels from the hypothalamus, is a low-pressure venous system
what type of infarction occurs in the anterior lobe?
ischemic necrosis
what may this result in?
hypopituitarism - depending on the extent of destruction of anterior lobe cells
what type of patient is pituitary infarction most associated with?
postpartum
what is this referred to as?
Sheehan's syndrome
what happens to the anterior lobe in pregnancy, and why?
it doubles in size, due to the physiologic hyperplasia of lactotrophs
how does the blood supply change, and what is the result?
it stays the same, and pituitary hypoxia results
what complications of childbirth result in infarction?
hemorrhage, shock
is hypopituitarism immediate or delayed?
can be either
why might it be delayed?
progressive destruction of cells secondary to entrapment in postinfarction scarring
what are other predisposing conditions to necrosis of anterior pituitary lobe (5)?
1) DIC; 2) sickle cell anemia; 3) elevated intracranial pressure; 4) trauma; 5) shock
EMPTY SELLA SYNDROME
what does empty sella syndrome reefer to?
enlarged sella not filled with pituitary tissue
what classifications of empty sella syndrome are there (2)?
1) primary; 2) secondary
what is the predisposing developmental abnormality for primary empty sella syndrome?
incomplete diaphragma sellae
what does this abnormality allow to happen, and what is the result?
permits subarachnoid space to expand or balloon into sella (secondary to CSF pressure) which compresses the pituitary gland
who is primary empty sella syndrome most often diagnosed in?
obese multiparous women
what may have a role that is associated with obesity and pregnancy?
increased CSF pressure
how may empty sella syndrome cause symptoms (2)?
may cause hormonal distrurbances or mass effects, or may be asymptomatic
what is secondary empty sella syndrome caused by?
secondary to sellar enlargement by a tumor (pituitary macroadenoma) which leaves a sellar vacancy when it is destroyed or spontaneously necroses
DISORDERS OF THE POSTERIOR LOBE-HORMONE
what hormone comes from the posterior pituitary?
ADH
what disorder is caused by ADH deficiency?
diabetes insipidus
what problem results, and why?
dehydration from excessive excretion of free water
what are the main causes of DI (5)?
1) tumors of hypothalamus/pituitary; 2) inflammation of hypothalamus/pituitary; 3) head trauma; 4) surgical injury to hypothalamus/pituitary; 5) idiopathic
what is the treatment for DI?
administration of ADH
what is SIADH, and what is it caused by?
syndrome of inappropriate ADH - due to ADH excess
what problem results from the excessive resorption of free water?
dilutional hyponatremia
what symptoms may be caused by this dilutional hyponatremia (2)?
1) nausea/vomiting; 2) cerebral edema (and resultant neurologic dysfunction - confusion, coma, seizures)
what are the main causes of SIADH (3)?
1) ectopic secretion of ADH by malignant neoplasms (small cell lung carcinoma); 2) non-malignant lung diseases (TB); 3) intracranial lesions (trauma, infection, stroke)
what is the treatment for SIADH (2)?
1) water restriction; 2) identification and correction of underlying cause
what is the rationale for water restriction?
to accomplish slow normalization of serum sodium
why must it be slow (what may fast normalization (increase) in sodium cause?
rapid elevation may lead to CMP (central pontine myelinosis) which may be fatal
HYPOTHALAMIC ORIGIN OF ENCEPHALOPATHIES
what can hormonal disturbances from hypothalamic origin include (3)?
1) hypopituitarism; 2) hyperpituitarism; 3) diabetes insipidus - these can occur in combination
what are conditions causing hypothalamic origin endocrinopathies (2)?
1) infection; 2) inflammation