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Endocrine II midterm > Guerin: Pituitary > Flashcards

Guerin: Pituitary Flashcards

1
Q

What is the most common cause of hyperpituitarism ?

A

anterior lobe pituitary adenoma

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2
Q

What is the difference between a macro and micro adenoma?

A

> or < 1cm in diameter

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3
Q

What are functioning adenomas associated with?

A

distinct endocrine signs and symptoms

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4
Q

What do nonfunctioning adenomas presnt with?

A

mass effects, including visual disturbances

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5
Q

What are lactotroph adenomas

A
  • secrete prolactin

- can present with amenorrhea, galactorrhea, loss of libido, and infertility

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6
Q

What is a somatotroph adenoma

A
  • secretes GH

- presents with gigantism in children and acromegaly inadults; also with impaired glucose tolerance and diabete mellitus

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7
Q

What is corticotroph adenoma?

A

-secretes ACTH and presents with cushing syndrome and hpyperigmentation

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8
Q

What are the distinct morphologic features of most adenomas?

A
  • their cellular monomorphism and…

* *absence of reticulin network**

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9
Q

What is hypopopituitarism typically?

A

a destructive process of the anterior pituitary

-When combined with diabetes insipidus, think hypothalamic problem

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10
Q

What is pituitary apoplexy?

A

-a sudden hemorrhage into the pituitary gland (often an adenoma) and is a neurosurgical emergency

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11
Q

What is Sheehan syndrome?

A

-results from postpartum necrosis of the anterior pituitary

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12
Q

What do the clinically relevant posterior pituitary syndromes involve?

A
  • ADH!
  • Diabetes insipidus… too low
  • SIADH…. too high
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13
Q

Which part of the pituitary is just an extension of the hypothalamus?

A

Post pit

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14
Q

What are the things that the hypothalamus secretes?

A
  • TRH
  • PIF (dopamine)
  • CRH
  • GHRH
  • GIH (somatostatin)
  • GnRH
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15
Q

Which hormones are carried via portal vascular system?

A
  • TRH… TSH
  • PIF….PRL
  • CRH….ACTH
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16
Q

What are the anterior pituitary cell types and what do they secrete?

A
  • somatotrophs… GH
  • mammosomatotrophs…. GH and PRL
  • Lactotrophs…. PRL
  • Corticotrophs…. ACTH and POMC and MSH
  • Thyrotrophs… TSH
  • Gonadotrophs…. FSH and LH
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17
Q

What are the 2 hormones that the post pit makes?

A
  • Oxytocin

- ADH

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18
Q

What does Oxytocin do?

A
  • stimulates uterine contractions

- stimulates smooth muscle around lactiferous ducts

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19
Q

What does ADH do?

A
  • vasopressin

- conserve water

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20
Q

Where are the hormones that the post pit secretes made?

A

Hypothalamus

-stored in axon terminals

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21
Q

What is the visual effect of a pituitary tumor?

A

-bitemporal hemianopsia

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22
Q

What are the signs of elevated intracranial pressure?

A
  • headache
  • nausea
  • vomiting
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23
Q

What was bolded and bigger on the slide labeled “hyperpitutitarism”?

A
  • Pituitary adenomas

- if non-functional, can cause hypopituitarism

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24
Q

What is a pituitary adenoma?

A
  • functional
  • adults
  • micro is <1cm and macro is >1cm
  • Atypical adenomas: more likely to behave aggressively (invasive, recur)
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25
Q

what does a typical pituitary adenoma look like?

A
  • soft and well-circumscribed
  • when small, confined to the sella turcica
  • as they expand, they erode the sella turcica nad anterior clinoid processes
  • larger ones extend superiorly and often compress the optic chiasm and adjacent structures (like cranial nerves)
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26
Q

What will tell us that it is an adenoma as opposed to normal? (histology)

A

-monomorphism and the absence of a significant reticulin

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27
Q

What is the mutation in the G-protein signaling that renders the alpha subunit active all the time?

A

-GNAS

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28
Q

Lactotroph adenoma

A
  • most frequent type of hyperfunctioning pituitary adenoma- 30% of all clinically recognized cases
  • Secrete prolactin
  • range from small micradenomas to large tumors with mass effect
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29
Q

Clinical course of prolactinemia

A
  • amenorrhea, galactorrhea, loss of libido, and infertility

- in men and postmenopausal women, it may be subtle

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30
Q

When is it normal to have hyperprolactinemia?

A
  • preggo
  • nipple stimulation
  • response to many types of stress
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31
Q

What is hyperprolactinemia pathologic?

A
  • loss of dopamine mediated inhibition of prolactin (hypothalamus secretes dopamine)
  • damage of pituitary stalk (trauma)
  • drugs that block dopamine receptors on lactotroph cells
  • any mass in the suprasellar compartment may interfere with inhibitory effect of hypothalamus on prolactin secretion
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32
Q

Lactotroph adenoma treatment?

A
  • bromocriptine

- surgery

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33
Q

What is bromocriptine?

A

a dopamine receptor agonist that cuases the lesions to diminish in size

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34
Q

What is the second most common type of functioning pituitary adenoma?

A

Somatotroph adenomas

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35
Q

what do somatotroph adenomas secrete?

A

GH

  • stimulates hepatic secretion of IGF1
  • Gigantism in children
  • Acromegaly in adults
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36
Q

What is a somatotroph adenoma so big when it comes to clinical attention?

A

because we need a LOT of GH to cause clinical signs

-can take decades

37
Q

When does gigantism occur?

A
  • if it starts before the epihpyses have closed

- disproportionaltely long arms and legs

38
Q

When does acromegaly occur?

A
  • after closure of the epihpyses
  • large jaw and feet and hands
  • sausage fingers
  • increased bone density in both the spine and the hips
39
Q

How to diagnose somatotroph adenoma?

A
  • look for elevated serum GH and IGF-1 levels

- failure to suppress GH production in response to an oral load of glucose***

40
Q

Which test was very sensitive for acromegaly?

A

-look for failure to suppress GH production in response to an oral load of glucose

41
Q

tx of somatotroph adenoma

A
  • surgery

- pharmacotherapy: somatostatin analogs, GH receptor antagonists

42
Q

Mammosomatotroph adenomas

A
  • make both GH and prolactin
  • more frequently recognized
  • immunohistochemical reactivity for prolactin and GH
  • signs and symptoms of both
  • treatment same
43
Q

Corticotroph adenomas

A
  • Secrete ACTH… adrenal hypersecretion of cortisol… hypercortisolism (cushing syndrome)
  • usually microadenomas
  • Adenomas are PAS positive
44
Q

Clinical course of cushing syndrome

A
  • more later under adrenal gland… can be caused by a wide variety of conditions
  • Hirsutism, round face, buffalo hump, easy bruising, abdominal weight gain, stretch marks
45
Q

What is it called when there is hypercortisolism due to excessive production of ACTH by the pituitary?

A

Cushing Disease

46
Q

Nelson syndrome

A
  • pt with preexisting corticotroph microadenoma
  • occurs after surgical removal of the adrenal glands for treatment of Cushing syndrome
  • loss of inhibitory effect of adrenal corticosteroids…. large destructing pituitary adenoma with mass effect
  • hypercortisolism does not develop (no adrenal glands)
  • can get hyperpigmentation because of the stimulatory effect of other products of the ACTH precursor molecule on melanocytes
47
Q

Gonadotroph Adenomas

A
  • produce FSH and LH or nonfunctioning
  • can be difficult to recognize: secretes hormones ineffeiciently and variably
  • most frequently found in middle-aged men and women when they bocome large enough to cause mass effect
48
Q

What is the result of decreased LH?

A
  • decreased energy and libido in men (bc reduced testosterone
  • amenorrhea in premenopausal women
49
Q

Thyrotroph adenomas (TSH-producing)

A
  • uncommon, about 1% of all pituitary adenomas

- rare cause of hyperthyroidism

50
Q

Plurihormonal adenomas

A
  • elaborate more than one hormone
  • example: mammosomatotroph adenomas
  • others secrete multiple hormones
  • usually aggressive
51
Q

Nonfunctioning Pituitary Adenomas

A
  • 25-30% of all pituitary tumors
  • typically present with sypmtoms of mass effect
  • may also compress the residual ant pit… hypopituitarism
52
Q

What is pituitary apoplexy?

A

What we have abrupt hypopituitarism from acute intratumoral hemorrhage

53
Q

Pituitary Carcinoma

A
  • rare
  • <1% of pituitary tumors
  • defined by metastases
  • most are functional: most commonly PRL and ACTH
54
Q

Hypopituitarism

A
  • decreased secretion of pituitary hormons
  • can happen d/t diseases of the hypothalamus or of the pituitary
  • need to lose 75% of ant pit
55
Q

What should we think of if we see hypopituitarism+posterior pituitary dysfunction?

A

Hypothalamic origin

56
Q

Causes of hypopituitarism?

A
  • tumors
  • traumatic brain injury and SA hemorrhage
  • pituitary surgery or radiation
  • pituitary apoplexy
  • ischemic necrosis of the pituitary and Sheehan syndrome
57
Q

Sheehan syndrome

A
  • postpartum necrosis of the ant pit
  • most common form of clinically significant ischemic necrosis of the an pit
  • during preggo, the ant pit enlarges to almost twice its normal size… without increase in blood supply
  • any further reductin in blood supply from obstetric hemorrhage or shock may result in infarction of the anterior lobe
58
Q

Why does Sheehan syndrome affect the anterior lobe and not so much the posterior?

A

the post pit receives its blood directly from arterial branches, so it is much less susceptible to ischemic injury and therefore usually not affected

59
Q

if there is diminished secretion of ADH, what does that result in?

A

diabetes insipidus

60
Q

Primary Empty Sella

A

-defect in the diaphragma sella
-arachnoid mater and CSF herniate into the sella… expands sella and compresse pituitary
-obese women w/ multiple preggos
-pts present with visual field defects and occasionally with endocrine anomalies
-

61
Q

Clinical manifestations of hypopituitarisms?

A
  • varies depending on the specific hormones that are lacking
  • GH deficiency
  • Gonadotropin (LH and FSH) deficiency
  • TSH and ACTH deficiencies… hypothyroidism and hypoadrenalism
  • Prolactin deficiency…. failure of postpartum lactation
62
Q

MSH

A
  • melanocyte stimulating hormone
  • MSH is synthesized from the same precursor molecule that produces ACTH
  • Hypopituitarism can cause pallor due to a loss of stimulatory effects on melanocytes
63
Q

What do the clinically relevant post pit syndromes involve?

A

ADH

  • Dabetes insipidus
  • SIADH
64
Q

What does ADH increase the expression of in the collecting duct?

A

aquaporins

-so H2O can diffuse back into our blood stream

65
Q

Diabetes Insipidus

A
  • ADH deficiency
  • excessive urination
  • Central DI (brain) vs. Nephrogenic DI
66
Q

How to tell central DI from nephrogenic DI?

A

-see if the renal tubules are responsive to ADH

67
Q

Clinical manifestations of Diabetes Insipidus

A
  • pee a lot
  • increased serum sodium and osmolality
  • thirst and polydipsia
  • pts who can’t compensate and drink water may develop life-threatening dehydration
68
Q

SIADH

A
  • too much ADH
  • we resorb too much water
  • hyponatremia
69
Q

clinical manifestations of SIADH

A
  • hyponatremia
  • cerebral edema
  • resultant neurologic dysfunction
70
Q

Supresellar (hypothalamic) tumors

A

-may cause hypofunction or hyperfunction of the ant pit, DI, or a combo

71
Q

Most common tumors of the supresellar variety?

A
  • gliomas

- craniopharyngiomas

72
Q

Craniopharyngioma

A
  • remnants of Rathke puch
  • slow-growing
  • bimodal age distribution
  • patients usually present with headaches and visual disturbances
  • Children can present with growth retardation due to pituitary dypofunction and GH deficiency
  • 3-4 cm
  • optic chiasm or CN’s
73
Q

Adamantinomatous Craniopharyngioma

A
  • children
  • calcified
  • Nests or cords of stratified squamous epithelium with peripheral palisading and compact, lamellar keratin
  • Cyst formation: contains that “machine oil”
  • fibrosis and chronic inflammation
  • Extend little fingers of epithelium into adjacent brain…. a brisk glial reactionq
74
Q

Papillary Craniopharyngioma

A
  • adults
  • rarely calcified
  • both solid sheets and papillae lined by well-differentiated squamous epithelium…. lacks peripheral palisading
  • Usually lack keratin, calcification, and cysts
75
Q

Prognosis of Papillary Craniopharyngioma

A
  • excellent
  • larger lesions are more invasive but this does not impact on the prognosis
  • malignant transformation into squamous carcinomas: very rare, usually occurs after radiation
76
Q

What is the most common cause of hyperpituitarism

A

anterior lobe pituitary adenoma

77
Q

Macro vs microadenoma

A

1 cm

78
Q

How do functioning adenomas present?

A

distinct endocrine signs and symptoms

79
Q

How do nonfunctioning adenomas present?

A

mass effects, including visual disturbances

80
Q

Lactotroph adenomas

A

-secrete prolactin and can present with amenorrhea, galactorrhea, loss of libido, and infertility

81
Q

What is galactorrhea?

A

inappropriate production of milk

82
Q

Somatotroph adenomas

A

-secrete GH and present with gigantism in children and acromegaly in adults; also with impaired glucose tolerance and diabetes mellitus

83
Q

Corticotroph adenomas

A

-secrete ACTH and present with Cushing syndrome and hyperpigmentation

84
Q

What are the distinctive morphologic features of mos adenomas?

A
  • their cellular monomorphism

- absence of a reticulin network

85
Q

What causes hypopituitarism?

A

-destructive processes of the ant pit

86
Q

What do we think of when we see ant pit problems combined with diabetes insipidus?

A

-hypothalamic problem

87
Q

What is pituitary apoplexy?

A
  • sudden hemorrhage into the pituitary gland

- neurosurgical emergency

88
Q

What is Sheehan syndrome the result of?

A

-results from postpartum necrosis of the ant pit

89
Q

What do the clinically releavant Post pit syndromes involve?

A

ADH

  • DI (too low)
  • SIADH (too high)

Endocrine II midterm (13 decks)

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